Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2005
Publication Date: January 1, 2006
Citation: Nichols, M.H. 2006. Measured sediment yield rates from semiarid rangeland watersheds. Rangeland Ecol. and Manage. 59(1):55-62. Interpretive Summary: Sediment is one of the principle pollutants of surface water in the United States. One measure of the amount of sediment that leaves a watershed is sediment yield. In 1953, a project was started on the United States Department of Agriculture – Agricultural Research Service Walnut Gulch Experimental Watershed near Tombstone Arizona to measure sediment yield from rangeland watersheds. Through this research, baseline small watershed sediment yield data are now available for semiarid rangelands. Sediment yields from 8 study watersheds ranged from 0.5 m3/ha/yr to 3.0 m3/ha/year, with a mean of 1.4 m3/ha/year and a standard deviation of 1.0 m3/ha/year.. There is variability among the sediment yield from the 8 watersheds, largely in response runoff, which varies in response to rainfall patterns. This research is providing information that can be used to evaluate the impacts of watershed management on downstream sediment yield.
Technical Abstract: Sediment yields from eight subwatersheds within the United States Department of Agriculture – Agricultural Research Service Walnut Gulch Experimental Watershed (WGEW) were computed from stock pond sediment accumulation measurements, water level records, and estimates of sediment transported in pond overflows. Sediment accumulation records ranging from 30 to 47 years were evaluated for subwatershed ranging from 35.2 to 159.5 ha. Within the 150 km sq WGEW, sediment yield from upland watersheds ranged from 0.5 m3/ha/yr to 3.0 m3/ha/year, with a mean of 1.4 m3/ha/year and a standard deviation of 1.0 m3/ha/year. Although sediment yields were temporally and spatially variable, with the exception of runoff volume, no significant relationships were found to explain sediment yield variability. The spatial and temporal variability in sediment yields adds to the complexity of generalizing sediment yield rates across rangeland regions.