ARS | Publication request: A sediment budget for a small semiarid watershed in southeastern Arizona, USA

Submitted to: Geomorphology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 2, 2012
Publication Date: December 7, 2012
Citation: Nichols, M.H., Nearing, M.A., Polyakov, V.O., Stone, J.J. 2012. A sediment budget for a small semiarid watershed in southeastern Arizona, USA. Geomorphology. 180-181: 137-145.

Interpretive Summary: Sediment budgets are a method for accounting for the processes that move sediment within a watershed. The processes of erosion, transport, and deposition associated both hillslopes and channels are included. A sediment budget was developed for a 47 ha watershed based on hydrologic, geomorphic, erosion, and sediment data collected from 1963 through 2006 on the USDA-ARS Walnut Gulch Experimental Watershed in the southwestern US. The channel network on the watershed is downcutting and is a source of sediment in the upper end of the watershed; however hillslopes are the dominant source of sediment, contributing 97% of the overall total. The watershed outlet is controlled by an earth dam. The pond associated with the dam is a site where sediment that was delivered through the watershed is deposited. Because the study watershed is controlled by an earth dam at the outlet, the sediment budget was balanced with a high degree of confidence. With the 44 year study period, variations in precipitation and runoff create variations in the amount of erosion, transport, and deposition. Measurements of sediment at the watershed outlet pond are not sensitive to temporal and spatial variability in watershed sediment dynamics.

Technical Abstract: A sediment budget was developed for a 47 ha watershed based on hydrologic, geomorphic, erosion, and sediment data collected from 1963 through 2006 on the USDA-ARS Walnut Gulch Experimental Watershed in the southwestern US. Although the channel network is well developed and incising in the upper end of the watershed, hillslopes are the dominant source of sediment, contributing 97% of the overall total. Because the study watershed is controlled by an earth dam at the outlet, the sediment budget was balanced with a high degree of confidence. With the 44 year study period, temporally variable precipitation and runoff patterns create spatially variable sediment transfers. Watershed outlet sediment yield measurements are not sensitive to temporal and spatial variability in watershed sediment dynamics.