Sediment yields from unit-source semiarid watersheds at Walnut Gulch

Abstract

[1] This study reports sediment yields from seven small (0.18-5.42 ha) watersheds in Southern Arizona measured from 1995 to 2005. Sediment concentrations and total event sediment yields were related to storm-runoff characteristics, and statistical relationships were developed to estimate sediment yields for events with missing data. Precipitation ranged from 263 to 298 mm yr-1, runoff ranged from 8.2 to 26.4 mm yr-1, and sediment yields ranged from 0.07 to 5.71 ha-1 yr-1, with an areal average of 2.2 t ha-1 yr-1. For six of the seven watersheds, between 6 and 10 events produced 50% of the total sediment yields over the 11-year period. On the seventh watershed, two storms produced 66% of the sediment because of differences in the geomorphology and vegetation characteristics of that area. Differences between sediment yields from all watersheds were attributable to instrumentation, watershed morphology, degree of channel incision, and vegetation. Copyright 2007 by the American Geophysical Union.