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  • 1. Ali, A. Md
    et al.
    Solomatine, D. P.
    Di Baldassarre, Giuliano
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Assessing the impact of different sources of topographic data on 1-D hydraulic modelling of floods2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 1, p. 631-643Article in journal (Refereed)
    Abstract [en]

    Topographic data, such as digital elevation models (DEMs), are essential input in flood inundation modelling. DEMs can be derived from several sources either through remote sensing techniques (spaceborne or airborne imagery) or from traditional methods (ground survey). The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), the light detection and ranging (lidar), and topographic contour maps are some of the most commonly used sources of data for DEMs. These DEMs are characterized by different precision and accuracy. On the one hand, the spatial resolution of low-cost DEMs from satellite imagery, such as ASTER and SRTM, is rather coarse (around 30 to 90 m). On the other hand, the lidar technique is able to produce high-resolution DEMs (at around 1 m), but at a much higher cost. Lastly, contour mapping based on ground survey is time consuming, particularly for higher scales, and may not be possible for some remote areas. The use of these different sources of DEM obviously affects the results of flood inundation models. This paper shows and compares a number of 1-D hydraulic models developed using HEC-RAS as model code and the aforementioned sources of DEM as geometric input. To test model selection, the outcomes of the 1-D models were also compared, in terms of flood water levels, to the results of 2-D models (LISFLOOD-FP). The study was carried out on a reach of the Johor River, in Malaysia. The effect of the different sources of DEMs (and different resolutions) was investigated by considering the performance of the hydraulic models in simulating flood water levels as well as inundation maps. The outcomes of our study show that the use of different DEMs has serious implications to the results of hydraulic models. The outcomes also indicate that the loss of model accuracy due to re-sampling the highest resolution DEM (i.e. lidar 1 m) to lower resolution is much less than the loss of model accuracy due to the use of lowcost DEM that have not only a lower resolution, but also a lower quality. Lastly, to better explore the sensitivity of the 1-D hydraulic models to different DEMs, we performed an uncertainty analysis based on the GLUE methodology.

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  • 2.
    Arnal, Louise
    et al.
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England.;European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England..
    Cloke, Hannah L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England.;Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England.;CNDS, Ctr Nat Hazards & Disaster Sci, S-75236 Uppsala, Sweden..
    Stephens, Elisabeth
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England..
    Wetterhall, Fredrik
    European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England..
    Prudhomme, Christel
    European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England.;Loughborough Univ Technol, Dept Geog, Loughborough LE11 3TU, Leics, England.;NERC Ctr Ecol & Hydrol, Wallingford OX10 8BB, Oxon, England..
    Neumann, Jessica
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England..
    Krzeminski, Blazej
    European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England..
    Pappenberger, Florian
    European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England..
    Skilful seasonal forecasts of streamflow over Europe?2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 4, p. 2057-2072Article in journal (Refereed)
    Abstract [en]

    This paper considers whether there is any added value in using seasonal climate forecasts instead of historical meteorological observations for forecasting streamflow on seasonal timescales over Europe. A Europe-wide analysis of the skill of the newly operational EFAS (European Flood Awareness System) seasonal streamflow forecasts (produced by forcing the Lisflood model with the ECMWF System 4 seasonal climate forecasts), benchmarked against the ensemble streamflow prediction (ESP) forecasting approach (produced by forcing the Lisflood model with historical meteorological observations), is undertaken. The results suggest that, on average, the System 4 seasonal climate forecasts improve the streamflow predictability over historical meteorological observations for the first month of lead time only (in terms of hindcast accuracy, sharpness and overall performance). However, the predictability varies in space and time and is greater in winter and autumn. Parts of Europe additionally exhibit a longer predictability, up to 7 months of lead time, for certain months within a season. In terms of hindcast reliability, the EFAS seasonal streamflow hindcasts are on average less skilful than the ESP for all lead times. The results also highlight the potential usefulness of the EFAS seasonal streamflow forecasts for decision-making (measured in terms of the hindcast discrimination for the lower and upper terciles of the simulated streamflow). Although the ESP is the most potentially useful forecasting approach in Europe, the EFAS seasonal streamflow forecasts appear more potentially useful than the ESP in some regions and for certain seasons, especially in winter for almost 40 % of Europe. Patterns in the EFAS seasonal streamflow hindcast skill are however not mirrored in the System 4 seasonal climate hindcasts, hinting at the need for a better understanding of the link between hydrological and meteorological variables on seasonal timescales, with the aim of improving climate-model-based seasonal streamflow forecasting.

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  • 3.
    Ayala, Ana I.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Nonlinearity and Climate Group, Department of Applied Physics, University of Geneva, 1211 Geneva 4, Switzerland.
    Moras, Simone
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pierson, Donald C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Simulations of future changes in thermal structure of Lake Erken: proof of concept for ISIMIP2b lake sector local simulation strategy2020In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 24, no 6, p. 3311-3330Article in journal (Refereed)
    Abstract [en]

    This paper, as a part of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b), assesses the impacts of different levels of global warming on the thermal structure of Lake Erken (Sweden). The General Ocean Turbulence Model (GOTM) one-dimensional hydrodynamic model was used to simulate water temperature when using ISIMIP2b bias-corrected climate model projections as input. These projections have a daily time step, while lake model simulations are often forced at hourly or shorter time steps. Therefore, it was necessary to first test the ability of GOTM to simulate Lake Erken water temperature using daily vs hourly meteorological forcing data. In order to do this, three data sets were used to force the model as follows: (1) hourly measured data, (2) daily average data derived from the first data set, and (3) synthetic hourly data created from the daily data set using generalised regression artificial neural network methods. This last data set is developed using a method that could also be applied to the daily time step ISIMIP scenarios to obtain hourly model input if needed. The lake model was shown to accurately simulate Lake Erken water temperature when forced with either daily or synthetic hourly data. Long-term simulations forced with daily or synthetic hourly meteorological data suggest that by the late 21st century the lake will undergo clear changes in thermal structure. For the representative concentration pathway (RCP) scenario, namely RCP2.6, surface water temperature was projected to increase by 1.79 and 1.36 C when the lake model was forced at daily and hourly resolutions respectively, and for RCP6.0 these increases were projected to be 3.08 and 2.31 C. Changes in lake stability were projected to increase, and the stratification duration was projected to be longer by 13 and 11 d under RCP2.6 scenario and 22 and 18 d under RCP6.0 scenario for daily and hourly resolutions. Model changes in thermal indices were very similar when using either the daily or synthetic hourly forcing, suggesting that the original ISIMIP climate model projections at a daily time step can be sufficient for the purpose of simulating lake water temperature.

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  • 4.
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Searching for the Holy Grail of scientific hydrology: Q(t) = H((S)under-left-arrow, (R)under-left-arrow, Delta t)A as closure2006In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 10, no 5, p. 609-618Article in journal (Refereed)
    Abstract [en]

    Representative Elementary Watershed concepts provide a useful scale-independent framework for the representation of hydrological processes. The balance equations that underlie the concepts, however, require the definition of boundary flux closures that should be expected to be scale dependent. The relationship between internal state variables of an REW element and the boundary fluxes will be nonlinear, hysteretic and scale-dependent and may depend on the extremes of the heterogeneities within the REW. Because of the nonlinearities involved, simple averaging of local scale flux relationships are unlikely to produce an adequate description of the closure problem at the REW scale. Hysteresis in the dynamic response is demonstrated for some small experimental catchments and it is suggested that at least some of this hysteresis can be represented by the use of simple transfer functions. The search for appropriate closure schemes is the second most important problem in hydrology of the 21st Century (the most important is providing the techniques to measure integrated fluxes and storages at useful scales). The closure problem is a scientific Holy Grail: worth searching for even if a general solution might ultimate prove impossible to find.

  • 5.
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Towards integrated environmental models of everywhere: uncertainty, data and modelling as a learning process2007In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 11, no 1, p. 460-467Article in journal (Refereed)
    Abstract [en]

    Developing integrated environmental models of everywhere such as are demanded by the requirements of, for example, implementing the Water Framework Directive in Europe, is constrained by the limitations of current understanding and data availability. The possibility of such models raises questions about system design requirements to allow modelling as a learning and data assimilation process in the representation of places, which might well be treated as active objects in such a system. Uncertainty in model predictions not only poses issues about the value of different types of data in characterising places and constraining predictive uncertainty but also about how best to present the pedigree of such uncertain predictions to users and decision-makers.

  • 6.
    Beven, Keith
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Smith, P. J.
    Wood, A.
    On the colour and spin of epistemic error (and what we might do about it)2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, no 10, p. 3123-3133Article in journal (Refereed)
    Abstract [en]

    Disinformation as a result of epistemic error is an issue in hydrological modelling. In particular the way in which the colour in model residuals resulting from epistemic errors should be expected to be non-stationary means that it is difficult to justify the spin that the structure of residuals can be properly represented by statistical likelihood functions. To do so would be to greatly overestimate the information content in a set of calibration data and increase the possibility of both Type I and Type II errors. Some principles of trying to identify periods of disinformative data prior to evaluation of a model structure of interest, are discussed. An example demonstrates the effect on the estimated parameter values of a hydrological model.

  • 7.
    Di Baldassarre, Giuliano
    et al.
    Univ Bologna, Fac Civil Engn, DISTART, Bologna, Italy.
    CASTELLARIN, A
    BRATH, A
    Relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy2006In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 10, no 4, p. 589-601Article in journal (Refereed)
    Abstract [en]

    Several hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day, observed at a dense network of raingauges sited in northern central Italy, are analyzed using an approach based on L-moments. The analysis investigates the statistical properties of rainfall extremes and detects significant relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we developed a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The applicability of the regional model was assessed through Monte Carlo simulations. The uncertainty of the model for ungauged sites was quantified through an extensive crossvalidation.

  • 8.
    Di Baldassarre, Giuliano
    et al.
    UNESCO-IHE Institute for Water Education, Delft, the Netherlands.
    Kooy, M.
    Kemerink, J. S.
    Brandimarte, L.
    Towards understanding the dynamic behaviour of floodplains as human-water systems2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 8, p. 3235-3244Article in journal (Refereed)
    Abstract [en]

    This paper offers a conceptual approach to explore the complex dynamics of floodplains as fully coupled human-water systems. A number of hydrologists have recently investigated the impact of human activities (such as flood control measures, land-use changes, and settlement patterns) on the frequency and severity of floods. Meanwhile, social scientists have shown how interactions between society and waters in deltas and floodplain areas, including the frequency and severity of floods, have an impact on the ways in which social relations unfold (in terms of governance processes, policies, and institutions) and societies are organised (spatially, politically, and socially). However, we argue that the interactions and associated feedback mechanisms between hydrological and social processes remain largely unexplored and poorly understood. Thus, there is a need to better understand how the institutions and governance processes interact with hydrological processes in deltas and floodplains to influence the frequency and severity of floods, while (in turn) hydrological processes co-constitute the social realm and make a difference for how social relations unfold to shape governance processes and institutions. Our research goal, therefore, is not in identifying one or the other side of the cycle (hydrological or social), but in explaining the relationship between them: how, when, where, and why they interact, and to what result for both social relations and hydrological processes? We argue that long time series of hydrological and social data, along with remote sensing data, can be used to observe floodplain dynamics from unconventional approaches, and understand the complex interactions between water and human systems taking place in floodplain areas, across scales and levels of human impacts, and within different hydro-climatic conditions, socio-cultural settings, and modes of governance.

  • 9.
    Di Baldassarre, Giuliano
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Ctr Nat Hazards & Disaster Sci CNDS, Uppsala, Sweden.
    Kreibich, Heidi
    GFZ German Res Ctr Geosci, D-14473 Potsdam, Germany.
    Vorogushyn, Sergiy
    GFZ German Res Ctr Geosci, D-14473 Potsdam, Germany.
    Aerts, Jeroen
    Vrije Univ Amsterdam, Inst Environm Studies, NL-1081 Amsterdam, Netherlands.
    Arnbjerg-Nielsen, Karsten
    Tech Univ Denmark, Dept Environm Engn, DK-2800 Lyngby, Denmark.
    Barendrecht, Marlies
    Vienna Univ Technol, Ctr Water Resource Syst, A-1040 Vienna, Austria.
    Bates, Paul
    Univ Bristol, Sch Geog Sci, Bristol BS8 1SS, Avon, England.
    Borga, Marco
    Univ Padua, Dept Land Environm Agr & Forestry, I-35122 Padua, Italy.
    Botzen, Wouter
    Vrije Univ Amsterdam, Inst Environm Studies, NL-1081 Amsterdam, Netherlands;Univ Utrecht, Sch Econ USE, Utrecht, Netherlands.
    Bubeck, Philip
    Univ Potsdam, Inst Earth & Environm Sci, D-14469 Potsdam, Germany.
    De Marchi, Bruna
    Univ Bergen, Ctr Study Sci & Humanities, SVT, N-5020 Bergen, Norway.
    Llasat, Carmen
    Univ Barcelona, Dept Appl Phys, E-08007 Barcelona, Spain.
    Mazzoleni, Maurizio
    IHE Delft, Dept Integrated Water Syst & Governance, NL-2601 Delft, Netherlands.
    Molinari, Daniela
    Politecn Milan, Dept Civil & Environm Engn, I-20133 Milan, Italy.
    Mondino, Elena
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Ctr Nat Hazards & Disaster Sci CNDS, Uppsala, Sweden.
    Mård, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Ctr Nat Hazards & Disaster Sci CNDS, Uppsala, Sweden.
    Petrucci, Olga
    CNR, Res Inst Geohydrol Protect, CNR, I-87036 Arcavacata Di Rende, CS, Italy.
    Scolobig, Anna
    Swiss Fed Inst Technol, Dept Environm Syst Sci, CH-8092 Zurich, Switzerland.
    Viglione, Alberto
    Vienna Univ Technol, Ctr Water Resource Syst, A-1040 Vienna, Austria.
    Ward, Philip J.
    Vrije Univ Amsterdam, Inst Environm Studies, NL-1081 Amsterdam, Netherlands.
    Hess Opinions: An interdisciplinary research agenda to explore the unintended consequences of structural flood protection2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 11, p. 5629-5637Article in journal (Refereed)
    Abstract [en]

    One common approach to cope with floods is the implementation of structural flood protection measures, such as levees or flood-control reservoirs, which substantially reduce the probability of flooding at the time of implementation. Numerous scholars have problematized this approach. They have shown that increasing the levels of flood protection can attract more settlements and high-value assets in the areas protected by the new measures. Other studies have explored how structural measures can generate a sense of complacency, which can act to reduce preparedness. These paradoxical risk changes have been described as "levee effect", "safe development paradox" or "safety dilemma". In this commentary, we briefly review this phenomenon by critically analysing the intended benefits and unintended effects of structural flood protection, and then we propose an interdisciplinary research agenda to uncover these paradoxical dynamics of risk.

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  • 10.
    Di Baldassarre, Giuliano
    et al.
    Department of Hydroinformatics and Knowledge Management, UNESCO-IHE Institute for Water Education, Delft, The Netherlands.
    Montanari, A
    Uncertainty in river discharge observations: a quantitative analysis2009In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 13, no 6, p. 913-921Article in journal (Refereed)
    Abstract [en]

    This study proposes a framework for analysing and quantifying the uncertainty of river flow data. Such uncertainty is often considered to be negligible with respect to other approximations affecting hydrological studies. Actually, given that river discharge data are usually obtained by means of the so-called rating curve method, a number of different sources of error affect the derived observations. These include: errors in measurements of river stage and discharge utilised to parameterise the rating curve, interpolation and extrapolation error of the rating curve, presence of unsteady flow conditions, and seasonal variations of the state of the vegetation (i.e. roughness). This study aims at analysing these sources of uncertainty using an original methodology. The novelty of the proposed framework lies in the estimation of rating curve uncertainty, which is based on hydraulic simulations. These latter are carried out on a reach of the Po River (Italy) by means of a one-dimensional (1-D) hydraulic model code (HEC-RAS). The results of the study show that errors in river flow data are indeed far from negligible.

  • 11.
    Di Baldassarre, Giuliano
    et al.
    Department of Integrated Water Systems and Governance, UNESCO-IHE, Delft, the Netherlands.
    Viglione, A.
    Carr, G.
    Kuil, L.
    Salinas, J. L.
    Blöschl, G.
    Socio-hydrology: conceptualising human-flood interactions2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 8, p. 3295-3303Article in journal (Refereed)
    Abstract [en]

    Over history, humankind has tended to settle near streams because of the role of rivers as transportation corridors and the fertility of riparian areas. However, human settlements in floodplains have been threatened by the risk of flooding. Possible responses have been to resettle away and/or modify the river system by building flood control structures. This has led to a complex web of interactions and feedback mechanisms between hydrological and social processes in settled floodplains. This paper is an attempt to conceptualise these interplays for hypothetical human-flood systems. We develop a simple, dynamic model to represent the interactions and feedback loops between hydrological and social processes. The model is then used to explore the dynamics of the human-flood system and the effect of changing individual characteristics, including external forcing such as technological development. The results show that the conceptual model is able to reproduce reciprocal effects between floods and people as well as the emergence of typical patterns. For instance, when levees are built or raised to protect floodplain areas, their presence not only reduces the frequency of flooding, but also exacerbates high water levels. Then, because of this exacerbation, higher flood protection levels are required by society. As a result, more and more flooding events are avoided, but rare and catastrophic events take place.

  • 12.
    El Tahir, M. El Haj
    et al.
    Department of Geosciences, University of Oslo, Norway.
    Kaab, A.
    Department of Geosciences, University of Oslo, Norway.
    Xu, C. -Y
    Department of Geosciences, University of Oslo, Norway.
    Identification and mapping of soil erosion areas in the Blue Nile, Eastern Sudan using multispectral ASTER and MODIS satellite data and the SRTM elevation model2010In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 14, no 7, p. 1167-1178Article in journal (Refereed)
    Abstract [en]

    The area of the Upper Blue Nile in Eastern Sudan is considered prone to soil erosion which is an important indicator of the land degradation process. In this study, an erosion identification and mapping approach is developed based on adaptations to the regional characteristics of the study area and the availability of data. This approach is derived from fusion between remote sensing data and geographical information systems (GIS). The developed model is used to map the spatial distribution of soil erosion caused by the rains of 2006 using automatic classification of multispectral Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. Shuttle Radar Topography Mission (SRTM) digital elevation model is used to orthoproject ASTER data. A maximum likelihood classifier is trained with four classes, Gully, Flat_land, Mountain and Water and applied to images from March and December 2006. Validation is done with field data from December and January 2006/2007. The results allow the identification of erosion gullies and subsequent estimation of eroded area. Consequently, the results are up-scaled using Moderate Resolution Imaging Spectroradiometer (MODIS) products of the same dates. Because the selected study site is representative of the wider Blue Nile region, it is expected that the approach presented could be applied to larger areas.

  • 13.
    Ewen, Tracy
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;ETH, Ctr Climate Syst Modeling, Zurich, Switzerland..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland.;Stockholm Univ, Dept Phys Geog & Quaternary Geol, Stockholm, Sweden..
    Learning about water resource sharing through game play2016In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 20, no 10, p. 4079-4091Article in journal (Refereed)
    Abstract [en]

    Games are an optimal way to teach about water resource sharing, as they allow real-world scenarios to be enacted. Both students and professionals learning about water resource management can benefit from playing games, through the process of understanding both the complexity of sharing of resources between different groups and decision outcomes. Here we address how games can be used to teach about water resource sharing, through both playing and developing water games. An evaluation of using the web-based game Irrigania in the classroom setting, supported by feedback from several educators who have used Irrigania to teach about the sustainable use of water resources, and decision making, at university and high school levels, finds Irrigania to be an effective and easy tool to incorporate into a curriculum. The development of two water games in a course for masters students in geography is also presented as a way to teach and communicate about water resource sharing. Through game development, students learned soft skills, including critical thinking, problem solving, team work, and time management, and overall the process was found to be an effective way to learn about water resource decision outcomes. This paper concludes with a discussion of learning outcomes from both playing and developing water games.

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  • 14.
    Ferdous, Md Ruknul
    et al.
    IHE Delft Inst Water Educ, Dept Integrated Water Syst & Governance, NL-2611 AX Delft, Netherlands;Univ Amsterdam, Fac Social & Behav Sci, NL-1012 WX Amsterdam, Netherlands.
    Wesselink, Anna
    IHE Delft Inst Water Educ, Dept Integrated Water Syst & Governance, NL-2611 AX Delft, Netherlands.
    Brandimarte, Luigia
    KTH, Dept Sustainable Dev Environm Sci & Engn, Stockholm, Sweden.
    Slager, Kymo
    Deltares, NL-2600 MH Delft, Netherlands.
    Zwarteveen, Margreet
    IHE Delft Inst Water Educ, Dept Integrated Water Syst & Governance, NL-2611 AX Delft, Netherlands;Univ Amsterdam, Fac Social & Behav Sci, NL-1012 WX Amsterdam, Netherlands.
    Di Baldassarre, Giuliano
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. IHE Delft Inst Water Educ, Dept Integrated Water Syst & Governance, NL-2611 AX Delft, Netherlands;CNDS, Ctr Nat Hazards & Disaster Sci, S-75236 Uppsala, Sweden.
    Socio-hydrological spaces in the Jamuna River floodplain in Bangladesh2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 10, p. 5159-5173Article in journal (Refereed)
    Abstract [en]

    Socio-hydrology aims to understand the dynamics and co-evolution of coupled human-water systems, with research consisting of generic models as well as specific case studies. In this paper, we propose a concept to help bridge the gap between these two types of socio-hydrological studies: socio-hydrological spaces (SHSs). A socio-hydrological space is a geographical area in a landscape. Its particular combination of hydrological and social features gives rise to the emergence of distinct interactions and dynamics (patterns) between society and water. Socio-hydrological research on human-flood interactions has found two generic responses, "fight" or "adapt". Distilling the patterns resulting from these responses in case studies provides a promising way to relate contextual specificities to the generic patterns described by conceptual models. Through the use of SHSs, different cases can be compared globally without aspiring to capturing them in a formal model. We illustrate the use of SHS for the Jamuna floodplain, Bangladesh. We use narratives and experiences of local experts and inhabitants to empirically describe and delimit SHS. We corroborated the resulting classification through the statistical analysis of primary data collected for the purpose (household surveys and focus group discussions) and secondary data (statistics, maps etc.). Our example of the use of SHSs shows that the concept draws attention to how historical patterns in the co-evolution of social behaviour, natural processes and technological interventions give rise to different landscapes, different styles of living and different ways of organising livelihoods. This provides a texture to the more generic patterns generated by socio-hydrological models, promising to make the resulting analysis more directly useful for decision makers. We propose that the usefulness of this concept in other floodplains, and for other socio-hydrological systems than floodplains, should be explored.

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  • 15. Gebrehiwot, S. G.
    et al.
    Ilstedt, U.
    Gardenas, A. I.
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Thirty-two watersheds (31-4350 km(2)), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R-2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows.

  • 16.
    Gong, Lebing
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Data-driven scale extrapolation: estimating yearly discharge for a large region by small sub-basins2014In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 18, no 1, p. 343-352Article in journal (Refereed)
    Abstract [en]

    Large-scale hydrological models and land surface models are so far the only tools for assessing current and future water resources. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited availability and quality of data, as well as model uncertainties. A new purely data-driven scale-extrapolation method to estimate discharge for a large region solely from selected small sub-basins, which are typically 1-2 orders of magnitude smaller than the large region, is proposed. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin. In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 5% of the gauged area. There exist multiple sets of sub-basins whose climate and hydrology resemble those of the gauged area equally well. Those multiple sets estimate annual discharge for the gauged area consistently well with 6% average error. The scale-extrapolation method is completely data-driven; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin.

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  • 17.
    Gong, Lebing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Halldin, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Xu, Chong-Yu
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Department of Geosciences, University of Oslo, Oslo, Norway.
    Large-scale runoff generation: parsimonious parameterisation using high-resolution topography2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, no 8, p. 2481-2494Article in journal (Refereed)
    Abstract [en]

    World water resources have primarily been analysed by global-scale hydrological models in the last decades. Runoff generation in many of these models are based on process formulations developed at catchments scales. The division between slow runoff (baseflow) and fast runoff is primarily governed by slope and spatial distribution of effective water storage capacity, both acting at very small scales. Many hydrological models, e. g. VIC, account for the spatial storage variability in terms of statistical distributions; such models are generally proven to perform well. The statistical approaches, however, use the same runoff-generation parameters everywhere in a basin. The TOPMODEL concept, on the other hand, links the effective maximum storage capacity with real-world topography. Recent availability of global high-quality, high-resolution topographic data makes TOPMODEL attractive as a basis for a physically-based runoff-generation algorithm at large scales, even if its assumptions are not valid in flat terrain or for deep groundwater systems. We present a new runoff-generation algorithm for large-scale hydrology based on TOPMODEL concepts intended to overcome these problems. The TRG (topography-derived runoff generation) algorithm relaxes the TOPMODEL equilibrium assumption so baseflow generation is not tied to topography. TRG only uses the topographic index to distribute average storage to each topographic index class. The maximum storage capacity is proportional to the range of topographic index and is scaled by one parameter. The distribution of storage capacity within large-scale grid cells is obtained numerically through topographic analysis. The new topography-derived distribution function is then inserted into a runoff-generation framework similar VIC's. Different basin parts are parameterised by different storage capacities, and different shapes of the storage-distribution curves depend on their topographic characteristics. The TRG algorithm is driven by the HydroSHEDS dataset with a resolution of 3 '' (around 90 m at the equator). The TRG algorithm was validated against the VIC algorithm in a common model framework in 3 river basins in different climates. The TRG algorithm performed equally well or marginally better than the VIC algorithm with one less parameter to be calibrated. The TRG algorithm also lacked equifinality problems and offered a realistic spatial pattern for runoff generation and evaporation.

  • 18.
    Harrigan, Shaun
    et al.
    European Ctr Medium Range Weather Forecasts ECMWF, Forecast Dept, Reading, England..
    Zsoter, Ervin
    European Ctr Medium Range Weather Forecasts ECMWF, Forecast Dept, Reading, England.;Univ Reading, Dept Geog & Environm Sci, Reading, England..
    Cloke, Hannah L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Univ Reading, Dept Geog & Environm Sci, Reading, England.;Univ Reading, Dept Meteorol, Reading, England.;Ctr Nat Hazards & Disaster Sci, CNDS, Uppsala, Sweden..
    Salamon, Peter
    European Commiss, Joint Res Ctr JRC, Ispra, Italy..
    Prudhomme, Christel
    European Ctr Medium Range Weather Forecasts ECMWF, Forecast Dept, Reading, England.;Ctr Ecol & Hydrol CEH, Wallingford, England.;Univ Loughborough, Dept Geog & Environm, Loughborough, England..
    Daily ensemble river discharge reforecasts and real-time forecasts from the operational Global Flood Awareness System2023In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 27, no 1, p. 1-19Article in journal (Refereed)
    Abstract [en]

    Operational global-scale hydrological forecasting systems are usedto help manage hydrological extremes such as floods and droughts. The vastamounts of raw data that underpin forecast systems and the ability togenerate information on forecast skill have, until now, not been publiclyavailable. As part of the Global Flood Awareness System (GloFAS; https://www.globalfloods.eu/, last access: 3 December 2022) service evolution, in this paper daily ensemble river discharge reforecasts and real-time forecast datasets are made free and openly available through the Copernicus Climate Change Service (C3S) Climate Data Store (CDS). They include real-time forecast data starting on 1 January 2020 updated operationally every day and a 20-year set of reforecasts and associated metadata. This paper describes the model components and configuration used to generate the real-time river discharge forecasts and the reforecasts. An evaluation of ensemble forecast skill using the continuous ranked probability skill score (CRPSS) was also undertaken for river points around the globe. Results show that GloFAS is skilful in over 93 % of catchments in the short (1 to 3 d) and medium range (5 to 15 d) against a persistence benchmark forecast and skilful in over 80 % of catchments out to the extended range (16 to 30 d) against a climatological benchmark forecast. However, the strength of skill varies considerably by location with GloFAS found to have no or negative skill at longer lead times in broad hydroclimatic regions in tropical Africa, western coast of South America, and catchments dominated by snow and ice in high northern latitudes. Forecast skill is summarised as a new headline skill score available as a new layer on the GloFAS forecast Web Map Viewer to aid user interpretation and understanding of forecast quality.

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  • 19. Humborg, Christoph
    et al.
    Mörth, Carl-Magnus
    Sundbom, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Wulff, Fredrik
    Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives2007In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 11, no 5, p. 1593-1607Article in journal (Refereed)
    Abstract [en]

    The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices and increased hydropower demand (for N, P and Si) and of global warming, i.e., changes in hydrological patterns (for C). These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes may increase due to higher livestock densities in those countries recently acceded to the EU, whereas P and Si fluxes may decrease due to an improved sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates could eventually substitute diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether dissolved organic carbon and alkalinity, which have opposite feedbacks to global warming, will increase in similar amounts, because the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.

  • 20. Jaramillo, F.
    et al.
    Cory, N.
    Arheimer, B.
    Laudon, H.
    van der Velde, Y.
    Hasper, T. B.
    Teutschbein, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Uddling, J.
    Dominant effect of increasing forest biomass on evapotranspiration: Interpretations of movement in Budyko Space2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, p. 567-580Article in journal (Refereed)
    Abstract [en]

    During the last 6 decades, forest biomass has increased in Sweden mainly due to forest management, with a possible increasing effect on evapotranspiration. However, increasing global CO2 concentrations may also trigger physiological water-saving responses in broadleaf tree species, and to a lesser degree in some needleleaf conifer species, inducing an opposite effect. Additionally, changes in other forest attributes may also affect evapotranspiration. In this study, we aimed to detect the dominating effect(s) of forest change on evapotranspiration by studying changes in the ratio of actual evapotranspiration to precipitation, known as the evaporative ratio, during the period 1961-2012. We first used the Budyko framework of water and energy availability at the basin scale to study the hydroclimatic movements in Budyko space of 65 temperate and boreal basins during this period. We found that movements in Budyko space could not be explained by climatic changes in precipitation and potential evapotranspiration in 60% of these basins, suggesting the existence of other dominant drivers of hydroclimatic change. In both the temperate and boreal basin groups studied, a negative climatic effect on the evaporative ratio was counteracted by a positive residual effect. The positive residual effect occurred along with increasing standing forest biomass in the temperate and boreal basin groups, increasing forest cover in the temperate basin group and no apparent changes in forest species composition in any group. From the three forest attributes, standing forest biomass was the one that could explain most of the variance of the residual effect in both basin groups. These results further suggest that the water-saving response to increasing CO2 in these forests is either negligible or overridden by the opposite effect of the increasing forest biomass. Thus, we conclude that increasing standing forest biomass is the dominant driver of long-term and large-scale evapotranspiration changes in Swedish forests.

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  • 21.
    Jenicek, Michal
    et al.
    Charles Univ Prague, Fac Sci, Dept Phys Geog & Geoecol, Prague, Czech Republic..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Zappa, Massimiliano
    Swiss Fed Inst Forest, Snow & Landscape Res WSL, Birmensdorf, Switzerland..
    Staudinger, Maria
    Univ Zurich, Dept Geog, Zurich, Switzerland..
    Jonas, Tobias
    WSL Inst Snow & Avalanche Res SLF, Davos, Switzerland..
    Importance of maximum snow accumulation for summer low flows in humid catchments2016In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 20, no 2, p. 859-874Article in journal (Refereed)
    Abstract [en]

    Winter snow accumulation obviously has an effect on the following catchment runoff. The question is, however, how long this effect lasts and how important it is compared to rainfall inputs. Here we investigate the relative importance of snow accumulation on one critical aspect of runoff, namely the summer low flow. This is especially relevant as the expected increase of air temperature might result in decreased snow storage. A decrease of snow will affect soil and ground-water storages during spring and might cause low streamflow values in the subsequent warm season. To understand these potential climate change impacts, a better evaluation of the effects of inter-annual variations in snow accumulation on summer low flow under current conditions is central. The objective in this study was (1) to quantify how long snowmelt affects runoff after melt-out and (2) to estimate the sensitivity of catchments with different elevation ranges to changes in snowpack. To find suitable predictors of summer low flow we used long time series from 14 Alpine and pre-Alpine catchments in Switzerland and computed different variables quantifying winter and spring snow conditions. In general, the results indicated that maximum winter snow water equivalent (SWE) influenced summer low flow, but could expectedly only partly explain the observed inter-annual variations. On average, a decrease of maximum SWE by 10% caused a decrease of minimum discharge in July by 6-9% in catchments higher than 2000 ma.s.l. This effect was smaller in middle-and lower-elevation catchments with a decrease of minimum discharge by 2-5% per 10% decrease of maxi-mum SWE. For higher-and middle-elevation catchments and years with below-average SWE maximum, the minimum discharge in July decreased to 70-90% of its normal level. Additionally, a reduction in SWE resulted in earlier low-flow occurrence in some cases. One other important factor was the precipitation between maximum SWE and summer low flow. When only dry preceding conditions in this period were considered, the importance of maximum SWE as a predictor of low flows increased. We assessed the sensitivity of individual catchments to the change of maximum SWE using the non-parametric Theil-Sen approach as well as an elasticity index. Both sensitivity indicators increased with increasing mean catchment elevation, indicating a higher sensitivity of summer low flow to snow accumulation in Alpine catchments compared to lower-elevation pre-Alpine catchments.

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  • 22.
    Kauffeldt, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Halldin, Sven
    Rodhe, Allan
    Xu, Chong-Yu
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Westerberg, Ida K.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Disinformative data in large-scale hydrological modelling2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 7, p. 2845-2857Article in journal (Refereed)
    Abstract [en]

    Large-scale hydrological modelling has become an important tool for the study of global and regional water resources, climate impacts, and water-resources management. However, modelling efforts over large spatial domains are fraught with problems of data scarcity, uncertainties and inconsistencies between model forcing and evaluation data. Model-independent methods to screen and analyse data for such problems are needed. This study aimed at identifying data inconsistencies in global datasets using a pre-modelling analysis, inconsistencies that can be disinformative for subsequent modelling. The consistency between (i) basin areas for different hydrographic datasets, and (ii) between climate data (precipitation and potential evaporation) and discharge data, was examined in terms of how well basin areas were represented in the flow networks and the possibility of water-balance closure. It was found that (i) most basins could be well represented in both gridded basin delineations and polygon-based ones, but some basins exhibited large area discrepancies between flow-network datasets and archived basin areas, (ii) basins exhibiting too-high runoff coefficients were abundant in areas where precipitation data were likely affected by snow undercatch, and (iii) the occurrence of basins exhibiting losses exceeding the potential-evaporation limit was strongly dependent on the potential-evaporation data, both in terms of numbers and geographical distribution. Some inconsistencies may be resolved by considering subgrid variability in climate data, surface-dependent potential-evaporation estimates, etc., but further studies are needed to determine the reasons for the inconsistencies found. Our results emphasise the need for pre-modelling data analysis to identify dataset inconsistencies as an important first step in any large-scale study. Applying data-screening methods before modelling should also increase our chances to draw robust conclusions from subsequent model simulations.

  • 23. Leedal, D.
    et al.
    Weerts, A. H.
    Smith, P. J.
    Beven, Keith J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Application of data-based mechanistic modelling for flood forecasting at multiple locations in the Eden catchment in the National Flood Forecasting System (England and Wales)2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 1, p. 177-185Article in journal (Refereed)
    Abstract [en]

    The Delft Flood Early Warning System provides a versatile framework for real-time flood forecasting. The UK Environment Agency has adopted the Delft framework to deliver its National Flood Forecasting System. The Delft system incorporates new flood forecasting models very easily using an "open shell" framework. This paper describes how we added the data-based mechanistic modelling approach to the model inventory and presents a case study for the Eden catchment (Cumbria, UK).

  • 24.
    Lin, H.
    et al.
    Penn State Univ, Dept Crop & Soil Sci, University Pk, USA .
    Vogel, H. -J
    UFZ Ctr Environm Res, Dept Soil Phys, Halle, Germany .
    Seibert, J.
    Stockholm Univ, Dept Phys Geog & Quaternary Geol, S-10691 Stockholm, Sweden.
    Towards holistic studies of the Earth's Critical Zone: hydropedology perspectives' Preface2010In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 14, no 3, p. 479-480Article in journal (Refereed)
  • 25.
    Matthews, Gwyneth
    et al.
    Univ Reading, Dept Meteorol, Reading, Berks, England..
    Barnard, Christopher
    European Ctr Medium Range Weather Forecasts, Forecast Dept, Reading, Berks, England..
    Cloke, Hannah L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Reading, Dept Meteorol, Reading, Berks, England.;European Ctr Medium Range Weather Forecasts, Forecast Dept, Reading, Berks, England.;Univ Reading, Dept Geog & Environm Sci, Reading, Berks, England..
    Dance, Sarah L.
    Univ Reading, Dept Meteorol, Reading, Berks, England.;Univ Reading, Dept Math & Stat, Reading, Berks, England..
    Jurlina, Toni
    European Ctr Medium Range Weather Forecasts, Forecast Dept, Reading, Berks, England..
    Mazzetti, Cinzia
    European Ctr Medium Range Weather Forecasts, Forecast Dept, Reading, Berks, England..
    Prudhomme, Christel
    European Ctr Medium Range Weather Forecasts, Forecast Dept, Reading, Berks, England.;Univ Loughborough, Dept Geog, Loughborough, Leics, England.;UK Ctr Ecol & Hydrol, Wallingford, Oxon, England..
    Evaluating the impact of post-processing medium-range ensemble streamflow forecasts from the European Flood Awareness System2022In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 26, no 11, p. 2939-2968Article in journal (Refereed)
    Abstract [en]

    Streamflow forecasts provide vital information to aid emergency response preparedness and disaster risk reduction. Medium-range forecasts are created by forcing a hydrological model with output from numerical weather prediction systems. Uncertainties are unavoidably introduced throughout the system and can reduce the skill of the streamflow forecasts. Post-processing is a method used to quantify and reduce the overall uncertainties in order to improve the usefulness of the forecasts. The post-processing method that is used within the operational European Flood Awareness System is based on the model conditional processor and the ensemble model output statistics method. Using 2 years of reforecasts with daily timesteps, this method is evaluated for 522 stations across Europe. Post-processing was found to increase the skill of the forecasts at the majority of stations in terms of both the accuracy of the forecast median and the reliability of the forecast probability distribution. This improvement is seen at all lead times (up to 15 d) but is largest at short lead times. The greatest improvement was seen in low-lying, large catchments with long response times, whereas for catchments at high elevation and with very short response times the forecasts often failed to capture the magnitude of peak flows. Additionally, the quality and length of the observational time series used in the offline calibration of the method were found to be important. This evaluation of the post-processing method, and specifically the new information provided on characteristics that affect the performance of the method, will aid end users in making more informed decisions. It also highlights the potential issues that may be encountered when developing new post-processing methods.

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  • 26.
    Mazzoleni, Maurizio
    et al.
    Integrated Water Systems and Governance Department, IHE Delft Institute for Water Education, Delft, 2611AX, the Netherlands.
    Juliette Cortes Arevalo, Vivian
    Water Engineering and Management, University of Twente, Enschede, 7522 NB, the Netherlands.
    Wehn, Uta
    Integrated Water Systems and Governance Department, IHE Delft Institute for Water Education, Delft, 2611AX, the Netherlands.
    Alfonso, Leonardo
    Integrated Water Systems and Governance Department, IHE Delft Institute for Water Education, Delft, 2611AX, the Netherlands.
    Norbiato, Daniele
    Alto Adriatico Water Authority, Venice, Italy.
    Monego, Martina
    Alto Adriatico Water Authority, Venice, Italy.
    Ferri, Michele
    Alto Adriatico Water Authority, Venice, Italy.
    Solomatine, Dimitri P.
    Integrated Water Systems and Governance Department, IHE Delft Institute for Water Education, Delft, 2611AX, the Netherlands; Water Resources Management department, Water Problems Institute, Russian Academy of Sciences, Moscow, Russia; Water Resources Section, Delft University of Technology, Delft, 2628 CD, the Netherlands.
    Exploring the influence of citizen involvement on the assimilation of crowdsourced observations: A modelling study based on the 2013 flood event in the Bacchiglione catchment (Italy)2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 1, p. 391-416Article in journal (Refereed)
    Abstract [en]

    To improve hydrological predictions, real-time measurements derived from traditional physical sensors are integrated within mathematic models. Recently, traditional sensors are being complemented with crowdsourced data (social sensors). Although measurements from social sensors can be low cost and more spatially distributed, other factors like spatial variability of citizen involvement, decreasing involvement over time, variable observations accuracy and feasibility for model assimilation play an important role in accurate flood predictions. Only a few studies have investigated the benefit of assimilating uncertain crowdsourced data in hydrological and hydraulic models. In this study, we investigate the usefulness of assimilating crowdsourced observations from a heterogeneous network of static physical, static social and dynamic social sensors. We assess improvements in the model prediction performance for different spatial–temporal scenarios of citizen involvement levels. To that end, we simulate an extreme flood event that occurred in the Bacchiglione catchment  (Italy) in May 2013 using a semi-distributed hydrological model with the station at Ponte degli Angeli (Vicenza) as the prediction–validation point. A conceptual hydrological model is implemented by the Alto Adriatico Water Authority and it is used to estimate runoff from the different sub-catchments, while a hydraulic model is implemented to propagate the flow along the river reach. In both models, a Kalman filter is implemented to assimilate the crowdsourced observations. Synthetic crowdsourced observations are generated for either static social or dynamic social sensors because these measures were not available at the time of the study. We consider two sets of experiments: (i) assuming random probability of receiving crowdsourced observations and (ii) using theoretical scenarios of citizen motivations, and consequent involvement levels, based on population distribution. The results demonstrate the usefulness of integrating crowdsourced observations. First, the assimilation of crowdsourced observations located at upstream points of the Bacchiglione catchment ensure high model performance for high lead-time values, whereas observations at the outlet of the catchments provide good results for short lead times. Second, biased and inaccurate crowdsourced observations can significantly affect model results. Third, the theoretical scenario of citizens motivated by their feeling of belonging to a community of friends has the best effect in the model performance. However, flood prediction only improved when such small communities are located in the upstream portion of the Bacchiglione catchment. Finally, decreasing involvement over time leads to a reduction in model performance and consequently inaccurate flood forecasts.

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  • 27.
    Mazzoleni, Maurizio
    et al.
    UNESCO-IHE Institute for Water Education, Hydroinformatics Chair Group, Delft, the Netherlands.
    Verlaan, Martin
    Deltares, Delft, the Netherlands.
    Alfonso, Leonardo
    UNESCO-IHE Institute for Water Education, Hydroinformatics Chair Group, Delft, the Netherlands.
    Monego, Martina
    Alto Adriatico Water Authority, Venice, Italy.
    Norbiato, Daniele
    Alto Adriatico Water Authority, Venice, Italy.
    Ferri, Miche
    Alto Adriatico Water Authority, Venice, Italy.
    Solomatine, Dimitri P.
    UNESCO-IHE Institute for Water Education, Hydroinformatics Chair Group, Delft, the Netherlands; Delft University of Technology, Water Resources Section, Delft, the Netherlands.
    Can assimilation of crowdsourced data in hydrological modelling improve flood prediction?2017In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 21, no 2, p. 839-861Article in journal (Refereed)
    Abstract [en]

    Monitoring stations have been used for decades to properly measure hydrological variables and better predict floods. To this end, methods to incorporate these observations into mathematical water models have also been developed. Besides, in recent years, the continued technological advances, in combination with the growing inclusion of citizens in participatory processes related to water resources management, have encouraged the increase of citizen science projects around the globe. In turn, this has stimulated the spread of low-cost sensors to allow citizens to participate in the collection of hydrological data in a more distributed way than the classic static physical sensors do. However, two main disadvantages of such crowdsourced data are the irregular availability and variable accuracy from sensor to sensor, which makes them challenging to use in hydrological modelling. This study aims to demonstrate that streamflow data, derived from crowdsourced water level observations, can improve flood prediction if integrated in hydrological models. Two different hydrological models, applied to four case studies, are considered. Realistic (albeit synthetic) time series are used to represent crowdsourced data in all case studies. In this study, it is found that the data accuracies have much more influence on the model results than the irregular frequencies of data availability at which the streamflow data are assimilated. This study demonstrates that data collected by citizens, characterized by being asynchronous and inaccurate, can still complement traditional networks formed by few accurate, static sensors and improve the accuracy of flood forecasts.

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  • 28.
    Metcalfe, Peter
    et al.
    Univ Lancaster, Lancaster Environm Ctr, Lancaster, England.
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Lancaster, Lancaster Environm Ctr, Lancaster, England.
    Hankin, Barry
    Univ Lancaster, Lancaster Environm Ctr, Lancaster, England; JBA Consulting, Warrington, Cheshire, England.
    Lamb, Rob
    Univ Lancaster, Lancaster Environm Ctr, Lancaster, England; JBA Trust, Broughton Hall, Skipton, N Yorkshire, England.
    A new method, with application, for analysis of the impacts on flood risk of widely distributed enhanced hillslope storage2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 4, p. 2589-2605Article in journal (Refereed)
    Abstract [en]

    Enhanced hillslope storage is utilised in natural flood management in order to retain overland storm run-off and to reduce connectivity between fast surface flow pathways and the channel. Examples include excavated ponds, deepened or bunded accumulation areas, and gullies and ephemeral channels blocked with wooden barriers or debris dams.

    The performance of large, distributed networks of such measures is poorly understood. Extensive schemes can potentially retain large quantities of run-off, but there are indications that much of their effectiveness can be attributed to desynchronisation of sub-catchment flood waves. Inappropriately sited measures may therefore increase, rather than mitigate, flood risk. Fully distributed hydrodynamic models have been applied in limited studies but introduce significant computational complexity. The longer run times of such models also restrict their use for uncertainty estimation or evaluation of the many potential configurations and storm sequences that may influence the timings and magnitudes of flood waves.

    Here a simplified overland flow-routing module and semi-distributed representation of enhanced hillslope storage is developed. It is applied to the headwaters of a large rural catchment in Cumbria, UK, where the use of an extensive network of storage features is proposed as a flood mitigation strategy. The models were run within a Monte Carlo framework against data for a 2-month period of extreme flood events that caused significant damage in areas downstream. Acceptable realisations and likelihood weightings were identified using the GLUE uncertainty estimation framework. Behavioural realisations were rerun against the catchment model modified with the addition of the hillslope storage. Three different drainage rate parameters were applied across the network of hillslope storage.

    The study demonstrates that schemes comprising widely distributed hillslope storage can be modelled effectively within such a reduced complexity framework. It shows the importance of drainage rates from storage features while operating through a sequence of events. We discuss limitations in the simplified representation of overland flow-routing and representation and storage, and how this could be improved using experimental evidence. We suggest ways in which features could be grouped more strategically and thus improve the performance of such schemes.

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  • 29.
    Moras, Simone
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Ayala, Ana I
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Historical modelling of changes in Lake Erken thermal conditions2019In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 23, no 12, p. 5001-5016Article in journal (Refereed)
    Abstract [en]

    Historical lake water temperature records are a valuable source of information to assess the influence of climate change on lake thermal structure. However, in most cases such records span a short period of time and/or are incomplete, providing a less credible assessment of change. In this study, the hydrodynamic GOTM (General Ocean Turbulence Model, a hydrodynamic model configured in lake mode) was used to reconstruct daily profiles of water temperature in Lake Erken (Sweden) over the period 1961-2017 using seven climatic parameters as forcing data: wind speed (WS), air temperature (Air T), atmospheric pressure (Air P), relative humidity (RH), cloud cover (CC), precipitation (DP), and shortwave radiation (SWR). The model was calibrated against observed water temperature data collected during the study interval, and the calibrated model revealed a good match between modelled and observed temperature (RMSE = 1.089 degrees C). From the long-term simulations of water temperature, this study focused on detecting possible trends in water temperature over the entire study interval 1961-2017 and in the sub-intervals 1961-1988 and 1989-2017, since an abrupt change in air temperature was detected in 1988. The analysis of the simulated temperature showed that epilimnetic temperature increased on average by 0.444 and 0.792 degrees C per decade in spring and autumn in the sub-interval 1989-2017 Summer epilimnetic temperature increased by 0.351 degrees C per decade over the entire interval 1961-2017. Hypolimnetic temperature increased significantly in spring over the entire interval 1961-2017, by 0.148 and by 0.816 degrees C per decade in autumn in the subinterval 1989-2016. Whole-lake temperature showed a significant increasing trend in the sub-interval 1989-2017 during spring (0.404 degrees C per decade) and autumn (0.789 degrees C per decade, interval 1989-2016), while a significant trend was detected in summer over the entire study interval 1961-2017 (0.239 degrees C per decade). Moreover, this study showed that that changes in the phenology of thermal stratification have occurred over the 57-year period of study. Since 1961, the stability of stratification (Schmidt stability) has increased by 5.365 J M-2 per decade. The duration of thermal stratification has increased by 7.297 d per decade, corresponding to an earlier onset of stratification of similar to 16 d and to a delay of stratification termination of similar to 26 d. The average thermocline depth during stratification became shallower by similar to 1.345 m, and surface-bottom temperature difference increased over time by 0.249 degrees C per decade. The creation of a daily time step water temperature dataset not only provided evidence of changes in Erken thermal structure over the last decades, but is also a valuable resource of information that can help in future research on the ecology of Lake Erken. The use of readily available meteorological data to reconstruct Lake Erken's past water temperature is shown to be a useful method to evaluate long-term changes in lake thermal structure, and it is a method that can be extended to other lakes.

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  • 30. Oni, S.
    et al.
    Futter, M.
    Ledesma, J.
    Teutschbein, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Buttle, J.
    Laudon, H.
    Using dry and wet year hydroclimatic extremes to guide future hydrologic projections2016In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 20, no 7, p. 2811-2825Article in journal (Refereed)
    Abstract [en]

    There are growing numbers of studies on climate change impacts on forest hydrology, but limited attempts have been made to use current hydroclimatic variabilities to constrain projections of future climatic conditions. Here we used historical wet and dry years as a proxy for expected future extreme conditions in a boreal catchment. We showed that runoff could be underestimated by at least 35 % when dry year parameterizations were used for wet year conditions. Uncertainty analysis showed that behavioural parameter sets from wet and dry years separated mainly on precipitation-related parameters and to a lesser extent on parameters related to landscape processes, while uncertainties inherent in climate models (as opposed to differences in calibration or performance metrics) appeared to drive the overall uncertainty in runoff projections under dry and wet hydroclimatic conditions. Hydrologic model calibration for climate impact studies could be based on years that closely approximate anticipated conditions to better constrain uncertainty in projecting extreme conditions in boreal and temperate regions.

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  • 31. Pappenberger, F.
    et al.
    Frodsham, K.
    Beven, Keith J
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Romanowicz, R.
    Matgen, P.
    Fuzzy set approach to calibrating distributed flood inundation models using remote sensing observations2007In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 11, no 2, p. 739-752Article in journal (Refereed)
    Abstract [en]

    The paper presents a methodology for the estimation of uncertainty of inundation extent, which takes account of the uncertainty in the observed spatially distributed information and implements a fuzzy evaluation methodology. The Generalised Likelihood Uncertainty Estimation (GLUE) technique and the 2-D LISFLOOD-FP model were applied to derive the set of uncertain inundation realisations and resulting flood inundation maps. Conditioning of the inundation maps on fuzzified Synthetic Aperture Radar (SAR) images results in much more realistic inundation risk maps which can better depict the variable pattern of inundation extent than previously used methods. It has been shown that the evaluation methodology compares well to traditional approaches and can produce flood hazard maps that reflect the uncertainties in model evaluation.

  • 32.
    Pool, Sandra
    et al.
    Univ Zurich, Zurich, Switzerland.
    Vis, Marc J. P.
    Univ Zurich, Zurich, Switzerland.
    Knight, Rodney R.
    US Geol Survey, Nashville, USA.
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Zurich, Switzerland; Stockholm Univ, Stockholm, Sweden.
    Streamflow characteristics from modeled runoff time series importance of calibration criteria selection2017In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 21, no 11, p. 5443-5457Article in journal (Refereed)
    Abstract [en]

    Ecologically relevant streamflow characteristics (SFCs) of ungauged catchments are often estimated from simulated runoff of hydrologic models that were originally calibrated on gauged catchments. However, SFC estimates of the gauged donor catchments and subsequently the ungauged catchments can be substantially uncertain when models are calibrated using traditional approaches based on optimization of statistical performance metrics (e.g., Nash-Sutcliffe model efficiency). An improved calibration strategy for gauged catchments is therefore crucial to help reduce the uncertainties of estimated SFCs for ungauged catchments. The aim of this study was to improve SFC estimates from modeled runoff time series in gauged catchments by explicitly including one or several SFCs in the calibration process. Different types of objective functions were defined consisting of the Nash-Sutcliffe model efficiency, single SFCs, or combinations thereof. We calibrated a bucket-type runoff model (HBV-Hydrologiska Byrans Vattenavdelning-model) for 25 catchments in the Tennessee River basin and evaluated the proposed calibration approach on 13 ecologically relevant SFCs representing major flow regime components and different flow conditions. While the model generally tended to underestimate the tested SFCs related to mean and high-flow conditions, SFCs related to low flow were generally overestimated. The highest estimation accuracies were achieved by a SFC-specific model calibration. Estimates of SFCs not included in the calibration process were of similar quality when comparing a multi-SFC calibration approach to a traditional model efficiency calibration. For practical applications, this implies that SFCs should preferably be estimated from targeted runoff model calibration, and modeled estimates need to be carefully interpreted.

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  • 33.
    Ridolfi, Elena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. CNDS, Ctr Nat Hazards & Disaster Sci, Uppsala, Sweden..
    Kumar, Hemendra
    Auburn Univ, Dept Biosyst Engn, Auburn, AL 36849 USA..
    Bardossy, Andras
    Univ Stuttgart, Inst Hydraul Engn, Stuttgart, Germany..
    A methodology to estimate flow duration curves at partially ungauged basins2020In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 24, no 4, p. 2043-2060Article in journal (Refereed)
    Abstract [en]

    The flow duration curve (FDC) of streamflow at a specific site has a key role in the knowledge on the distribution and characteristics of streamflow at that site. The FDC gives information on the water regime, providing information to optimally manage the water resources of the river. In spite of its importance, because of the lack of streamflow gauging stations, the FDC construction can be a not straightforward task. In partially gauged basins, FDCs are usually built using regionalization among the other methods. In this paper we show that the FDC is not a characteristic of the basin only, but of both the basin and the weather. Different weather conditions lead to different FDCs for the same catchment. The differences can often be significant. Similarly, the FDC built at a site for a specific period cannot be used to retrieve the FDC at a different site for the same time window. In this paper, we propose a new methodology to estimate FDCs at partially gauged basins (i.e., target sites) using precipitation data gauged at another basin (i.e., donor site). The main idea is that it is possible to retrieve the FDC of a target period of time using the data gauged during a given donor time period for which data are available at both target and donor sites. To test the methodology, several donor and target time periods are analyzed and results are shown for different sites in the USA. The comparison between estimated and actually observed FDCs shows the reasonability of the approach, especially for intermediate percentiles.

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  • 34.
    Rinderer, M.
    et al.
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland.;Duke Univ, Nicholas Sch Environm, Durham, NC 27708 USA..
    Komakech, H. C.
    Nelson Mandela African Inst Sci & Technol, Arusha, Tanzania..
    Mueller, D.
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Wiesenberg, G. L. B.
    Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland..
    Qualitative soil moisture assessment in semi-arid Africa - the role of experience and training on inter-rater reliability2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 8, p. 3505-3516Article in journal (Refereed)
    Abstract [en]

    Soil and water management is particularly relevant in semi-arid regions to enhance agricultural productivity. During periods of water scarcity, soil moisture differences are important indicators of the soil water deficit and are traditionally used for allocating water resources among farmers of a village community. Here we present a simple, inexpensive soil wetness classification scheme based on qualitative indicators which one can see or touch on the soil surface. It incorporates the local farmers' knowledge on the best soil moisture conditions for seeding and brick making in the semi-arid environment of the study site near Arusha, Tanzania. The scheme was tested twice in 2014 with farmers, students and experts (April: 40 persons, June: 25 persons) for inter-rater reliability, bias of individuals and functional relation between qualitative and quantitative soil moisture values. During the test in April farmers assigned the same wetness class in 46% of all cases, while students and experts agreed on about 60% of all cases. Students who had been trained in how to apply the method gained higher inter-rater reliability than their colleagues with only a basic introduction. When repeating the test in June, participants were given improved instructions, organized in small subgroups, which resulted in a higher inter-rater reliability among farmers. In 66% of all classifications, farmers assigned the same wetness class and the spread of class assignments was smaller. This study demonstrates that a wetness classification scheme based on qualitative indicators is a robust tool and can be applied successfully regardless of experience in crop growing and education level when an in-depth introduction and training is provided. The use of a simple and clear layout of the assessment form is important for reliable wetness class assignments.

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  • 35.
    Rodhe, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Physical models for classroom teaching in hydrology2012In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 16, no 9, p. 3075-3082Article in journal (Refereed)
    Abstract [en]

    Hydrology teaching benefits from the fact that many important processes can be illustrated and explained with simple physical models. A set of mobile physical models has been developed and used during many years of lecturing at basic university level teaching in hydrology. One model, with which many phenomena can be demonstrated, consists of a 1.0-m-long plexiglass container containing an about 0.25-m-deep open sand aquifer through which water is circulated. The model can be used for showing the groundwater table and its influence on the water content in the unsaturated zone and for quantitative determination of hydraulic properties such as the storage coefficient and the saturated hydraulic conductivity. It is also well suited for discussions on the runoff process and the significance of recharge and discharge areas for groundwater. The flow paths of water and contaminant dispersion can be illustrated in tracer experiments using fluorescent or colour dye. This and a few other physical models, with suggested demonstrations and experiments, are described in this article. The finding from using models in classroom teaching is that it creates curiosity among the students, promotes discussions and most likely deepens the understanding of the basic processes.

  • 36.
    Rusca, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Heun, J.
    Schwartz, K.
    Water management simulation games and the construction of knowledge2012In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 16, no 8, p. 2749-2757Article in journal (Refereed)
  • 37. Schneider, P.
    et al.
    Pool, S.
    Strouhal, L.
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    True colors - experimental identification of hydrological processes at a hillslope prone to slide2014In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 18, no 2, p. 875-892Article in journal (Refereed)
    Abstract [en]

    This study investigated runoff formation processes of a pre-alpine hillslope prone to slide. The experimental pasture plot (40mx60 m) is located in the northern front range of the Swiss Alps on a 30 degrees steep hillslope (1180m a.s.l., 1500+ mm annual precipitation). A gleysol (H-Go-Gr) overlies weathered marlstone and conglomerate of subalpine molasse. We conducted sprinkling experiments on a subplot (10 mx10 m) with variable rainfall intensities. During both experiments fluorescein line-tracer injections into the topsoil, and sodium chloride (NaCl) injections into the sprinkling water were used to monitor flow velocities in the soil. The observed flow velocities for fluorescein in the soil were 1.2 and 1.4x10(-3) ms(-1). The NaCl breakthrough occurred almost simultaneously in all monitored discharge levels (0.05, 0.25 and 1.0m depth), indicating a high-infiltration capacity and efficient drainage of the soil. These initial observations suggested "transmissivity feedback", a form of subsurface stormflow, as the dominant runoff process. However, the results of a brilliant blue dye tracer experiment completely changed our perceptions of the hillslope's hydrological processes. Excavation of the dye-stained soils highlighted the dominance of "organic layer interflow", a form of shallow subsurface stormflow. The dye stained the entire H horizon, vertical soil fractures, and macropores (mostly worm burrows) up to 0.5m depth. Lateral drainage in the subsoil or at the soil-bedrock interface was not observed, and thus was limited to the organic topsoil. In the context of shallow landslides, the subsoil (Go/Gr) acted as an infiltration and exfiltration barrier, which produced significant lateral saturated drainage in the topsoil (H) and possibly a confined aquifer in the bedrock.

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  • 38. Seibert, J.
    et al.
    Beven, K. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Gauging the ungauged basin: how many discharge measurements are needed?2009In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 13, no 6, p. 883-892Article in journal (Refereed)
    Abstract [en]

    Runoff estimation in ungauged catchments is probably one of the most basic and oldest tasks of hydrologists. This long-standing issue has received increased attention recently due to the PUB (Prediction in Ungauged Basins) initiative. Given the challenges of predicting runoff for ungauged catchments one might argue that the best course of action is to take a few runoff measurements. In this study we explored how implementing such a procedure might support predictions in an ungauged basin. We used a number of monitored Swedish catchments as hypothetical ungauged basins where we pretended to start with no runoff data and then added different sub-sets of the available data to constrain a simple catchment model. These sub-sets consisted of a limited number of single runoff measurements; in other words these data represent what could be measured with limited efforts in an ungauged basin. We used a Monte Carlo approach and predicted runoff as a weighted ensemble mean of simulations using acceptable parameter sets. We found that the ensemble prediction clearly outperformed the predictions using single parameter sets and that surprisingly little runoff data was necessary to identify model parameterizations that provided good results for the ‘ungauged’ test periods. These results indicated that a few runoff measurements can contain much of the information content of continuous runoff time series. However, the study also indicated that results may differ significantly between catchments and also depend on the days chosen for taking the measurements.

  • 39.
    Seibert, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Uhlenbrook, S.
    Wagener, T.
    "Hydrology education in a changing world" Preface2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 4, p. 1393-1399Article in journal (Other academic)
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  • 40.
    Seibert, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Vis, M. J. P.
    Irrigania: a web-based game about sharing water resources2012In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 16, no 8, p. 2523-2530Article in journal (Refereed)
    Abstract [en]

    For teaching about collaboration and conflicts with regard to shared water resources, various types of games offer valuable opportunities. Single-player computer games often give much power to the player and ignore the fact that the best for some group might be difficult to achieve in reality if the individuals have their own interests. Here we present a new game called Irrigania, which aims at representing water conflicts among several actors in a simplified way. While simple in its rules, this game illustrates several game-theoretical situations typical for water-related conflicts. The game has been implemented as a web-based computer game, which allows easy application in classes. First classroom applications of the game indicated that, despite the simple rules, interesting patterns can evolve when playing the game in a class. These patterns can be used to discuss game theoretical considerations related to water resource sharing.

  • 41.
    Seibert, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Vis, M. J. P.
    Teaching hydrological modeling with a user-friendly catchment-runoff-model software package2012In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 16, no 9, p. 3315-3325Article in journal (Refereed)
    Abstract [en]

    Computer models, especially conceptual models, are frequently used for catchment hydrology studies. Teaching hydrological modeling, however, is challenging, since students have to both understand general model concepts and be able to use particular computer programs when learning to apply computer models. Here we present a new version of the HBV (Hydrologiska Byrans Vattenavdelning) model. This software provides a user-friendly version that is especially useful for education. Different functionalities, such as an automatic calibration using a genetic algorithm or a Monte Carlo approach, as well as the possibility to perform batch runs with predefined model parameters make the software interesting especially for teaching in more advanced classes and research projects. Different teaching goals related to hydrological modeling are discussed and a series of exercises is suggested to reach these goals.

  • 42.
    Staudinger, M.
    et al.
    Department of Geography, University of Zurich.
    Stahl, K.
    Institute of Hydrology Freiburg, Albert-Ludwigs University,.
    Seibert, Jan
    Department of Geography, University of Zurich.
    Clark, M. P.
    University Cooperation for Atmospheric Research, Boulder, Colorado.
    Tallaksen, L. M.
    Department of Geosciences, University of Oslo.
    Comparison of hydrological model structures based on recession and low flow simulations2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, no 11, p. 3447-3459Article in journal (Refereed)
    Abstract [en]

    Low flows are often poorly reproduced by commonly used hydrological models, which are traditionally designed to meet peak flow situations. Hence, there is a need to improve hydrological models for low flow prediction. This study assessed the impact of model structure on low flow simulations and recession behaviour using the Framework for Understanding Structural Errors (FUSE). FUSE identifies the set of subjective decisions made when building a hydrological model and provides multiple options for each modeling decision. Altogether 79 models were created and applied to simulate stream flows in the snow dominated headwater catchment Narsjø in Norway (119 km2). All models were calibrated using an automatic optimisation method. The results showed that simulations of summer low flows were poorer than simulations of winter low flows, reflecting the importance of different hydrological processes. The model structure influencing winter low flow simulations is the lower layer architecture, whereas various model structures were identified to influence model performance during summer.

  • 43. Staudinger, M.
    et al.
    Weiler, M.
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Quantifying sensitivity to droughts: an experimental modeling approach2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 3, p. 1371-1384Article in journal (Refereed)
    Abstract [en]

    Meteorological droughts like those in summer 2003 or spring 2011 in Europe are expected to become more frequent in the future. Although the spatial extent of these drought events was large, not all regions were affected in the same way. Many catchments reacted strongly to the meteorological droughts showing low levels of streamflow and groundwater, while others hardly reacted. Also, the extent of the hydrological drought for specific catchments was different between these two historical events due to different initial conditions and drought propagation processes. This leads to the important question of how to detect and quantify the sensitivity of a catchment to meteorological droughts. To assess this question we designed hydrological model experiments using a conceptual rainfall-runoff model. Two drought scenarios were constructed by selecting precipitation and temperature observations based on certain criteria: one scenario was a modest but constant progression of drying based on sorting the years of observations according to annual precipitation amounts. The other scenario was a more extreme progression of drying based on selecting months from different years, forming a year with the wettest months through to a year with the driest months. Both scenarios retained the observed intra-annual seasonality for the region. We evaluated the sensitivity of 24 Swiss catchments to these scenarios by analyzing the simulated discharge time series and modeled storage. Mean catchment elevation, slope and area were the main controls on the sensitivity of catchment discharge to precipitation. Generally, catchments at higher elevation and with steeper slopes appeared less sensitive to meteorological droughts than catchments at lower elevations with less steep slopes.

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  • 44.
    Teutschbein, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Seibert, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Is bias correction of regional climate model (RCM) simulations possible for non-stationary conditions?2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 12, p. 5061-5077Article in journal (Refereed)
    Abstract [en]

    In hydrological climate-change impact studies, regional climate models (RCMs) are commonly used to transfer large-scale global climate model (GCM) data to smaller scales and to provide more detailed regional information. Due to systematic and random model errors, however, RCM simulations often show considerable deviations from observations. This has led to the development of a number of correction approaches that rely on the assumption that RCM errors do not change over time. It is in principle not possible to test whether this underlying assumption of error stationarity is actually fulfilled for future climate conditions. In this study, however, we demonstrate that it is possible to evaluate how well correction methods perform for conditions different from those used for calibration with the relatively simple differential split-sample test.

  • 45.
    Towner, Jamie
    et al.
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England.
    Cloke, Hannah L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England;Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England;CNDS, Ctr Nat Hazards & Disaster Sci, S-75236 Uppsala, Sweden.
    Zsoter, Ervin
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England;European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG6 9AX, Berks, England.
    Flamig, Zachary
    Univ Chicago, Ctr Data Intens Sci, Chicago, IL 60637 USA.
    Hoch, Jannis M.
    Univ Utrecht, Dept Phys Geog, POB 80115, NL-3508 TC Utrecht, Netherlands;POB 177, NL-2600 MH Delft, Netherlands.
    Bazo, Juan
    Red Cross Red Crescent Climate Ctr, NL-2521 CV The Hague, Netherlands;UTP, Lima, Peru.
    de Perez, Erin Coughlan
    Columbia Univ, Int Res Inst Climate & Soc, Palisades, NY 10964 USA;Red Cross Red Crescent Climate Ctr, NL-2521 CV The Hague, Netherlands.
    Stephens, Elisabeth M.
    Univ Reading, Dept Geog & Environm Sci, Reading RG6 6AB, Berks, England.
    Assessing the performance of global hydrological models for capturing peak river flows in the Amazon basin2019In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 23, no 7, p. 3057-3080Article in journal (Refereed)
    Abstract [en]

    Extreme flooding impacts millions of people that live within the Amazon floodplain. Global hydrological models (GHMs) are frequently used to assess and inform the management of flood risk, but knowledge on the skill of available models is required to inform their use and development. This paper presents an intercomparison of eight different GHMs freely available from collaborators of the Global Flood Partnership (GFP) for simulating floods in the Amazon basin. To gain insight into the strengths and shortcomings of each model, we assess their ability to reproduce daily and annual peak river flows against gauged observations at 75 hydrological stations over a 19-year period (1997-2015). As well as highlighting regional variability in the accuracy of simulated streamflow, these results indicate that (a) the meteorological input is the dominant control on the accuracy of both daily and annual maximum river flows, and (b) ground-water and routing calibration of Lisflood based on daily river flows has no impact on the ability to simulate flood peaks for the chosen river basin. These findings have important relevance for applications of large-scale hydrological models, including analysis of the impact of climate variability, assessment of the influence of long-term changes such as land-use and anthropogenic climate change, the assessment of flood likelihood, and for flood forecasting systems.

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  • 46.
    Towner, Jamie
    et al.
    Univ Reading, Dept Geog & Environm Sci, Reading, Berks, England..
    Ficchi, Andrea
    Univ Reading, Dept Geog & Environm Sci, Reading, Berks, England..
    Cloke, Hannah L.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Reading, Dept Geog & Environm Sci, Reading, Berks, England.;Univ Reading, Dept Meteorol, Reading, Berks, England.;CNDS, Ctr Nat Hazards & Disaster Sci, Uppsala, Sweden..
    Bazo, Juan
    Red Cross Red Crescent Climate Ctr, NL-2521 CV The Hague, Netherlands.;Univ Tecnol Peru UTP, Lima, Peru..
    Coughlan de Perez, Erin
    Univ Tecnol Peru UTP, Lima, Peru.;Columbia Univ, Int Res Inst Climate & Soc, Palisades, NY 10964 USA..
    Stephens, Elisabeth M.
    Univ Reading, Dept Geog & Environm Sci, Reading, Berks, England..
    Influence of ENSO and tropical Atlantic climate variability on flood characteristics in the Amazon basin2021In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 25, no 7, p. 3875-3895Article in journal (Refereed)
    Abstract [en]

    Flooding in the Amazon basin is frequently attributed to modes of large-scale climate variability, but little attention is paid to how these modes influence the timing and duration of floods despite their importance to early warning systems and the significant impacts that these flood characteristics can have on communities. In this study, river discharge data from the Global Flood Awareness System (Glo-FAS 2.1) and observed data at 58 gauging stations are used to examine whether positive or negative phases of several Pacific and Atlantic indices significantly alter the characteristics of river flows throughout the Amazon basin (19792015). Results show significant changes in both flood magnitude and duration, particularly in the north-eastern Amazon for negative El Nino-Southern Oscillation (ENSO) phases when the sea surface temperature (SST) anomaly is positioned in the central tropical Pacific. This response is not identified for the eastern Pacific index, highlighting how the response can differ between ENSO types. Although flood magnitude and duration were found to be highly correlated, the impacts of large-scale climate variability on these characteristics are non-linear; some increases in annual flood maxima coincide with decreases in flood duration. The impact of flood timing, however, does not follow any notable pattern for all indices analysed. Finally, observed and simulated changes are found to be much more highly correlated for negative ENSO phases compared to the positive phase, meaning that GloFAS struggles to accurately simulate the differences in flood characteristics between El Nino and neutral years. These results have important implications for both the social and physical sectors working towards the improvement of early warning action systems for floods.

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  • 47.
    Van Loon, Anne F.
    et al.
    Univ Birmingham, Sch Geog Earth & Environm Sci, Water Sci Res Grp, Birmingham, W Midlands, England..
    Stahl, Kerstin
    Univ Freiburg, Fac Environm & Nat Resources, Hydrol Dept, Freiburg, Germany..
    Di Baldassarre, Giuliano
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Clark, Julian
    Univ Birmingham, Sch Geog Earth & Environm Sci, Human Geog Res Grp, Birmingham, W Midlands, England..
    Rangecroft, Sally
    Univ Birmingham, Sch Geog Earth & Environm Sci, Water Sci Res Grp, Birmingham, W Midlands, England..
    Wanders, Niko
    Princeton Univ, Civil & Environm Engn, Princeton, NJ 08544 USA..
    Gleeson, Tom
    Univ Victoria, Dept Civil Engn, Victoria, BC, Canada..
    Van Dijk, Albert I. J. M.
    Australian Natl Univ, Fenner Sch Environm & Soc, Canberra, ACT, Australia..
    Tallaksen, Lena M.
    Univ Oslo, Dept Geosci, Oslo, Norway..
    Hannaford, Jamie
    Ctr Ecol & Hydrol, Wallingford, Oxon, England..
    Uijlenhoet, Remko
    Wageningen Univ, Hydrol & Quantitat Water Management Grp, Wageningen, Netherlands..
    Teuling, Adriaan J.
    Wageningen Univ, Hydrol & Quantitat Water Management Grp, Wageningen, Netherlands..
    Hannah, David M.
    Univ Birmingham, Sch Geog Earth & Environm Sci, Water Sci Res Grp, Birmingham, W Midlands, England..
    Sheffield, Justin
    Svoboda, Mark
    Univ Nebraska, Natl Drought Mitigat Ctr, Lincoln, NE USA..
    Verbeiren, Boud
    Vrije Univ Brussel, Dept Hydrol & Hydraul Engn, Brussels, Belgium..
    Wagener, Thorsten
    Univ Bristol, Dept Civil Engn, Bristol, Avon, England.;Univ Bristol, Cabot Inst, Bristol, Avon, England..
    Van Lanen, Henny A. J.
    Wageningen Univ, Hydrol & Quantitat Water Management Grp, Wageningen, Netherlands..
    Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches2016In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 20, no 9, p. 3631-3650Article in journal (Refereed)
    Abstract [en]

    In the current human-modified world, or Anthropocene, the state of water stores and fluxes has become dependent on human as well as natural processes. Water deficits (or droughts) are the result of a complex interaction between meteorological anomalies, land surface processes, and human inflows, outflows, and storage changes. Our current inability to adequately analyse and manage drought in many places points to gaps in our understanding and to inadequate data and tools. The Anthropocene requires a new framework for drought definitions and research. Drought definitions need to be revisited to explicitly include human processes driving and modifying soil moisture drought and hydrological drought development. We give recommendations for robust drought definitions to clarify timescales of drought and prevent confusion with related terms such as water scarcity and overexploitation. Additionally, our understanding and analysis of drought need to move from single driver to multiple drivers and from uni-directional to multi-directional. We identify research gaps and propose analysis approaches on (1) drivers, (2) modifiers, (3) impacts, (4) feedbacks, and (5) changing the baseline of drought in the Anthropocene. The most pressing research questions are related to the attribution of drought to its causes, to linking drought impacts to drought characteristics, and to societal adaptation and responses to drought. Example questions include (i) What are the dominant drivers of drought in different parts of the world? (ii) How do human modifications of drought enhance or alleviate drought severity? (iii) How do impacts of drought depend on the physical characteristics of drought vs. the vulnerability of people or the environment? (iv) To what extent are physical and human drought processes coupled, and can feedback loops be identified and altered to lessen or mitigate drought? (v) How should we adapt our drought analysis to accommodate changes in the normal situation (i.e. what are considered normal or reference conditions) over time? Answering these questions requires exploration of qualitative and quantitative data as well as mixed modelling approaches. The challenges related to drought research and management in the Anthropocene are not unique to drought, but do require urgent attention. We give recommendations drawn from the fields of flood research, ecology, water management, and water resources studies. The framework presented here provides a holistic view on drought in the Anthropocene, which will help improve management strategies for mitigating the severity and reducing the impacts of droughts in future.

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  • 48.
    van Meerveld, H. J. Ilja
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland..
    Vis, Marc J. P.
    Univ Zurich, Dept Geog, Zurich, Switzerland..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Information content of stream level class data for hydrological model calibration2017In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 21, no 9, p. 4895-4905Article in journal (Refereed)
    Abstract [en]

    Citizen science can provide spatially distributed data over large areas, including hydrological data. Stream levels are easier to measure than streamflow and are likely also observed more easily by citizen scientists than streamflow. However, the challenge with crowd based stream level data is that observations are taken at irregular time intervals and with a limited vertical resolution. The latter is especially the case at sites where no staff gauge is available and relative stream levels are observed based on (in) visible features in the stream, such as rocks. In order to assess the potential value of crowd based stream level observations for model calibration, we pretended that stream level observations were available at a limited vertical resolution by transferring streamflow data to stream level classes. A bucket-type hydrological model was calibrated with these hypothetical stream level class data and subsequently evaluated on the observed streamflow records. Our results indicate that stream level data can result in good streamflow simulations, even with a reduced vertical resolution of the observations. Time series of only two stream level classes, e.g. above or below a rock in the stream, were already informative, especially when the class boundary was chosen towards the highest stream levels. There was some added value in using up to five stream level classes, but there was hardly any improvement in model performance when using more level classes. These results are encouraging for citizen science projects and provide a basis for designing observation systems that collect data that are as informative as possible for deriving model based streamflow time series for previously ungauged basins.

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  • 49.
    Westerberg, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Guerrero, José-Luis
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Seibert, Jan
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Halldin, Sven
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Calibration of hydrologic models using flow-duration curves2010In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, no 7, p. 9467-9522Article in journal (Refereed)
    Abstract [en]

    The degree of belief we have in predictions from hydrologic models depends on how well they can reproduce observations. Calibrations with traditional performance measures such as the Nash-Sutcliffe model efficiency are challenged by problems including: (1) uncertain discharge data, (2) variable importance of the performance with flow magnitudes, (3) influence of unknown input/output errors and (4) inability to evaluate model performance when observation time periods for discharge and model input data do not overlap. A new calibration method using flow-duration curves (FDCs) was developed which addresses these problems. The method focuses on reproducing the observed discharge frequency distribution rather than the exact hydrograph. It consists of applying limits of acceptability for selected evaluation points (EPs) of the observed uncertain FDC in the extended GLUE approach. Two ways of selecting the EPs were tested – based on equal intervals of discharge and of volume of water. The method was tested and compared to a calibration using the traditional model efficiency for the daily four-parameter WASMOD model in the Paso La Ceiba catchment in Honduras and for Dynamic TOPMODEL evaluated at an hourly time scale for the Brue catchment in Great Britain. The volume method of selecting EPs gave the best results in both catchments with better calibrated slow flow, recession and evaporation than the other criteria. Observed and simulated time series of uncertain discharges agreed better for this method both in calibration and prediction in both catchments without resulting in overpredicted simulated uncertainty. An advantage with the method is that the rejection criterion is based on an estimation of the uncertainty in discharge data and that the EPs of the FDC can be chosen to reflect the aims of the modelling application e.g. using more/less EPs at high/low flows. While the new method is less sensitive to epistemic input/output errors than the normal use of limits of acceptability applied directly to the time series of discharge, it still requires a reasonable representation of the distribution of inputs. Additional constraints might therefore be required in catchments subject to snow. The results suggest that the new calibration method can be useful when observation time periods for discharge and model input data do not overlap. The new method could also be suitable for calibration to regional FDCs while taking uncertainties in the hydrological model and data into account.

     

  • 50.
    Westerberg, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Guerrero, José-Luis
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Younger, P. M.
    Lancaster Environment Centre, Lancaster University, Lancaster, UK.
    Beven, Keith
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Seibert, J.
    Department of Physical Geography and Quartenary Geology, Stockholm University, Stockholm, Sweden.
    Halldin, Sven
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Freer, J. E.
    School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK.
    Xu, C. -Y
    Department of Geosciences, University of Oslo, Norway.
    Calibration of hydrological models using flow-duration curves2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, no 7, p. 2205-2227Article in journal (Refereed)
    Abstract [en]

    The degree of belief we have in predictions from hydrologic models will normally depend on how well they can reproduce observations. Calibrations with traditional performance measures, such as the Nash-Sutcliffe model efficiency, are challenged by problems including: (1) uncertain discharge data, (2) variable sensitivity of different performance measures to different flow magnitudes, (3) influence of unknown input/output errors and (4) inability to evaluate model performance when observation time periods for discharge and model input data do not overlap. This paper explores a calibration method using flow-duration curves (FDCs) to address these problems. The method focuses on reproducing the observed discharge frequency distribution rather than the exact hydrograph. It consists of applying limits of acceptability for selected evaluation points (EPs) on the observed uncertain FDC in the extended GLUE approach. Two ways of selecting the EPs were tested - based on equal intervals of discharge and of volume of water. The method was tested and compared to a calibration using the traditional model efficiency for the daily four-parameter WAS-MOD model in the Paso La Ceiba catchment in Honduras and for Dynamic TOPMODEL evaluated at an hourly time scale for the Brue catchment in Great Britain. The volume method of selecting EPs gave the best results in both catchments with better calibrated slow flow, recession and evaporation than the other criteria. Observed and simulated time series of uncertain discharges agreed better for this method both in calibration and prediction in both catchments. An advantage with the method is that the rejection criterion is based on an estimation of the uncertainty in discharge data and that the EPs of the FDC can be chosen to reflect the aims of the modelling application, e. g. using more/less EPs at high/low flows. While the method appears less sensitive to epistemic input/output errors than previous use of limits of acceptability applied directly to the time series of discharge, it still requires a reasonable representation of the distribution of inputs. Additional constraints might therefore be required in catchments subject to snow and where peak-flow timing at sub-daily time scales is of high importance. The results suggest that the calibration method can be useful when observation time periods for discharge and model input data do not overlap. The method could also be suitable for calibration to regional FDCs while taking uncertainties in the hydrological model and data into account.

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