uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
El Niño forcing on 10Be-based surface denudation rates in the northwestern Peruvian Andes?
Show others and affiliations
2010 (English)In: Geomorphology, ISSN 0169-555X, Vol. 123, no 3-4, 257-268 p.Article in journal (Refereed) Published
Abstract [en]

High magnitude precipitation events provide large contributions to landscape formation and surface denudation in arid environments. Here, we quantify the precipitation-dependent geomorphic processes within the Rio Piura drainage basin located on the Western Escarpment of the northern Peruvian Andes at 5 degrees S latitude. In this region, monsoonal easterly winds bring precipitation to the >3000 m asl high headwaters, from where the annual amount of precipitation decreases downstream toward the Pacific coast. Denudation rates are highest in the knickzones near the headwaters, similar to 200-300 mm ky(-1), and sediment discharge is limited by the transport capacity of the channel network. Every few years, this situation is perturbed by westerly, wind-driven heavy precipitation during El Nino events and results in supply-limited sediment discharge as indicated by bedrock channels. The detailed analysis of the stream-long profiles of two river basins within the Rio Piura catchment reveals a distinct knickzone in the transition zone between the easterly and westerly climatic influences, suggesting an En Nino forcing on the longitudinal channel profiles over at least Holocene timescales. Measured trunk stream catchment-wide denudation rates are up to ca. 300 mm ky(-1) and decrease successively downstream along the river profiles. Denudation rates of tributary rivers are ca. 200 mm ky(-1) near the plateau and show a stronger downstream decreasing trend than trunk stream rates. This suggests that the landscape is in a transient stage of local relief growth, which is driven by fluvial incision. This corroborates the results of paleoclimate studies that point towards higher El Nino frequencies during the past ca. 3000 years, leading to higher runoff and more erosion in the trunk channel compared to the hillslopes and thus growth of local relief. Downstream increases in channel gradient spatially coincide with the reaches of highest precipitation rates during El Nino events, we therefore interpret that Holocene landscape evolution has largely been controlled by climate. The ky-timescale of the Be-10 data together with the transience of the landscape implies that El Nino events in northwestern Peru have occurred since at least the Holocene, and that adjustment to channel incision is still taking place.

Place, publisher, year, edition, pages
2010. Vol. 123, no 3-4, 257-268 p.
Keyword [en]
Northwestern Peruvian Andes, El Nino, Be-10 denudation rates, Landscape transience
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:uu:diva-134162DOI: 10.1016/j.geomorph.2010.07.017ISI: 000282997200006OAI: oai:DiVA.org:uu-134162DiVA: diva2:371903
Available from: 2010-11-23 Created: 2010-11-22 Last updated: 2011-02-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text
By organisation
LUVALTandem Laboratory
In the same journal
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 326 hits
ReferencesLink to record
Permanent link

Direct link