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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #332093
Title: Sediment yield dynamics during the 1950s multi-year droughts from two ungauged basins in the Edwards Plateau, Texas

Author
item SANG, JOSEPH - Baylor University
item ALLEN, PETER - Baylor University
item DUNBAR, JOHN - Baylor University
item Arnold, Jeffrey
item WHITE, JOSEPH - Baylor University

Submitted to: Journal of Water Resource and Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2015
Publication Date: 11/25/2015
Publication URL: https://handle.nal.usda.gov/10113/5491317
Citation: Sang, J.K., Allen, P.M., Dunbar, J.A., Arnold, J.G., White, J.D. 2015. Sediment yield dynamics during the 1950s multi-year droughts from two ungauged basins in the Edwards Plateau, Texas. Journal of Water Resource and Protection. 7:1345-1362.

Interpretive Summary: The amount of sediment leaving the landscape and reaching rivers and reservoirs is highly dependent on climatic conditions. The multi-year drought of the 1950’s in Central Texas had a dramatic influence on sediment delivered to water bodies. The Soil and Water Assessment Tool (SWAT) was used to identify factors that contributed to erosion and to propose potential management to mitigate erosion and to mitigate erosion during future droughts. Watersheds within the San Saba River Basin in Texas were selected for the study. SWAT model results showed that the multi-year drought coupled with high livestock grazing resulted in loss of plant cover, causing high erosion rates from storms during and immediately after the drought. Maintenance of vegetation was shown to be critical in reducing water erosion associated with multi-year droughts.

Technical Abstract: Sediment yield dynamics on the Edwards Plateau region of Texas was dramatically influenced by a multi-year drought that occurred there during the 1950s. To assess the effect of this drought on sediment yield, we used the Soil and Water Assessment Tool (SWAT) to identify the factors that contributed erosion and to propose potential mitigation measures in case of future drought recurrence. The basins of interest to this study were Brady Creek One (BC 1) and Deep Creek Three (DC 3), located in McCulloch County, Texas. Although the streams in these basins are not gauged, the land cover and reservoir sediment budgets have been assessed in a past study. Calibration of SWAT flow simulation was accomplished using parameter transfer from a gauging station located in San Saba River. The results showed that sediment yield from storms above 60 mm was five times more during and immediately after drought period than during continuous wet seasons. Approximately half of the total drought period sediment yield was from five major rainstorms. The multi-year drought coupled with historical high grazing intensity resulted in significant loss of plant cover, which was considered critical in determining erosion and sedimentation rates. To test this hypothesis, the model was run for the periods of high land cover (1990s) using the 1950s multi-year drought data which showed that sediment yield was 24% of that simulated for 1950s land cover. It was concluded that maintenance of surface cover could play a critical role associated with multi-year drought extreme events.