Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2012
Publication Date: 9/1/2013
Citation: Wang, X., White, M.J., Tuppad, P., Lee, T., Srinivasan, R., Andrews, D., Narasimhan, B. 2013. Simulating sediment loading into the major reservoirs in Trinity River Basin. Journal of Soil and Water Conservation. 68(5):372-383. Interpretive Summary: The Upper Trinity Basin supplies water to about one-fourth of Texas' population. The anticipated rapid growth of North Central Texas has increased concerns that sediment and nutrients will continue to reduce reservoir volumes and water quality. In this study we used the Soil and Water Assessment Tool to model streamflow and sediment loads to 12 major reservoirs in the Upper Trinity River Basin. Increasing the number of ponds in the upland portion of the watersheds was among the most effective conservation practices examined. The model also predicts that Richland Chambers, Ray Hubbard and Lavon watersheds have significant channel erosion issues and that while implementing upland conservation practices, it is necessary to have corresponding conservation practices in channels to protect reservoirs.
Technical Abstract: The Upper Trinity Basin supplies water to about one-fourth of Texas' population. The anticipated rapid growth of North Central Texas will certainly increase regional demands for high quality drinking water. This has increased concerns that sediment and nutrient loads received by drinking water reservoirs are and will continue to reduce reservoir volumes and water quality. The objectives of this study are to calibrate and validate the Soil and Water Assessment Tool (SWAT) model for streamflow and sediment transport to assess current rates and sources of sediment loadings to 12 major reservoirs in the Upper Trinity River Basin (in seven 8-digit watersheds) and use the calibrated model for assessing the effects of ponds. SWAT performed well for streamflow, as evidenced by r2 values ranged from 0.55 to 0.95, Nash-Sutcliffe efficiency values ranged from 0.50 to 0.90 based on monthly streamflow comparisons between simulated and observed values for calibration and r2 values ranged from 0.58 to 0.95 for validation. SWAT was able to simulate sediment loads within 11% of observed values. Streamflow and sediment loads were variable across the Trinity River Basin, resulting in a wide range of calibrated parameter adjustments. Long-term predictions indicate that the Richland chambers, Ray Hubbard and Lavon watersheds have significant channel contribution to sediment loading reaching the reservoirs. The pond evaluation scenario shows the impact of ponds' removal by increasing sediment loadings to reservoirs from 4% to 48%. The results indicate that while implementing conservation practices, such as ponds, on upland areas, it is necessary to have corresponding conservation practices in channels for maximizing potential gains. A more detailed study for each of the basins assessed in this study will provide greater insight in identifying sensitive reaches for stabilization and restoration. Opportunity also exists for further evaluating the effects of optimizing pond size and placement to minimize reservoir sediment loading.