Sediment yield exceeds sediment production in arid region drainage basins

Abstract

We use 10 Be and 26 Al to determine long-term sediment generation rates, identify significant sediment sources, and test for landscape steady state in Nahal Yael, an extensively studied, hyperarid drainage basin in southern Israel. Comparing a 33 yr sediment budget with 33 paired 10 Be and 26 Al analyses indicates that short-term sediment yield (113-138 t• km-2 •yr-1) exceeds long-term sediment production (74 ± 16 t• km-2 •yr-1) by 53%-86%. The difference suggests that the basin is not in steady state, but is currently evacuating sediment accumulated during periods of more rapid sediment generation and lower sediment yield. Nuclide data indicate that (1) sediment leaving the basin is derived primarily from hillslope colluvium, (2) bedrock weathers more rapidly beneath a cover of colluvium than when exposed, and (3) long-term erosion rates of granite, schist, and amphibolite are similar.

Geomorphology of anomalously high glaciated mountains at the northwestern end of Tibet: Muztag Ata and Kongur Shan

“…We identify the dominant landforms and Earth surface processes that operate in the region. The relatively recent development of terrestrial cosmogenic nuclides (TCNs) methods to date landforms and to estimate rates of erosion allows quantification of landscape evolution (Brown et al, 1995;Granger et al, 1996;Clapp et al, 2000Clapp et al, , 2001Bierman and Caffee, 2001;Schaller et al, 2001;Matmon et al, 2003). Using these methods, we determine TCN concentrations in fluvial sediments and bedrock samples to help provide an outline of the recent geologic history of the massifs and to present the first estimates of the rates of Quaternary erosion.…”

Rates of basin-wide rockwall retreat in the K2 region of the Central Karakoram defined by terrestrial cosmogenic nuclide 10Be

“…In the second method, catchment-wide erosion rates have also been quantified by measuring the debris volume within rock glaciers of known ages (Humlum, 2000). More recently TCN methods allow rates of basin-wide erosion to be determined on geomorphic timescales (≤10 6 years) for various climatic environments (Brown et al, 1995;Granger et al, 1996;Clapp et al, 2000;Bierman and Caffee, 2001;Schäller et al, 2001;Matmon et al, 2003;Vance et al, 2003;Seong et al, 2009a). Heimsath and McGlynn (2008) and Seong et al (2009a) have applied this method to estimate rates of erosion for glacial catchments.…”

Monitoring periglacial processes: Towards construction of a global network

“…Kirschner et al, 2001), whereas in a small catchment the current slope instability can cause the reverse condition (e.g. Clapp et al, 2000).…”