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United States Department of Agriculture

Agricultural Research Service

Title: The Spatial Distribution of Sediment Sources and Sinks at the Watershed Scale in Semiarid Areas (Dissertation) 1289

Author
item NICHOLS, MARY

Submitted to: The Spatial Distribution of Sediment Sounces and Sinks at the Watershed
Publication Type: Other
Publication Acceptance Date: December 9, 1999
Publication Date: N/A

Interpretive Summary: Soil erosion and sediment yield are global problems. Currently, simulation models are available to predict hydrologic and erosion/sediment yield processes on semiarid watersheds. Based on simulation model results and th easily obtainable quantities of watershed slope, area, and the median diame of particles in the channel, an index was developed. The index provides a method for identifying zones of erosion and deposition within alluvial channels and thereby provides additional information on erosion and deposit processes at internal points on semiarid watersheds. Runoff and sediment yield were modeled on three semiarid watersheds identified as 63.223 (43.7 ha), 63.216 (84.2 ha), and 63.218 (58.3 ha) on the United States Department Agriculture-Agricultural Research Service Walnut Gulch Experimental Watersh near Tombstone, Arizona. The TLOSS model was calibrated, validated, and th used to simulate event runoff for the 1962-1996 period on Watershed 63.223 from 1966-1996 on Watersheds 63.216 and 63.218. The APOINT model was calibrated, validated, and used to simulate sediment yield for the same tim periods. Modeled event sediment yield was used in conjunction with field d and observations to develop and test the simple erosion/deposition index.

Technical Abstract: Soil erosion & sediment yield are global problems. An index has been developed which provides an easily computable method of identifying zones of erosion & deposition within alluvial channels. The index is not intended as a replacement for much more complex simulation models, but does provide a surrogate for measured data when evaluating the performance of simulation nmodels at internal watershed locations. The index depends only on simply computable watershed characteristics & does not depend at all on the parti- culars of a runoff event or set of runoff events. Runoff & sediment yield were modeled on three semiarid watersheds identified as 63.223 (43.7 ha), 63.216 (84.2 ha), & 63.218 (58.3 ha) on the USDA-ARS Walnut Gulch Experi- mental Watershed near Tombstone, Arizona. The TLOSS model was calibrated, validated, & used to simulate event runoff for the 1962-1996 period on Watershed 63.223 & from 1966-1996 on Watersheds 63.216 & 63.218. The APOINT Tmodel was calibrated, validated, & used to simulate sediment yield for the same time periods. Modeled event sediment yield was used in conjunction with field data to develop & test a simple erosion/ deposition index rela- ting the quantities of slope, area, & median particle diameter. Therefore, a method is now available to identify zones of erosion & deposition within alluvial channels & thereby provide additional information on erosion & deposition processes at internal points on semiarid watersheds.

Last Modified: 9/10/2014
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