WATER MANAGEMENT MULTITASKING: MANAGING RESERVOIRS FOR MORE THAN WATER SUPPLY

Most surface water management models are optimized for water supply concerns: avoiding floods and meeting downstream water demands. In many river basins, sustainability concerns go beyond water supply yet are still linked to hydrology and hydrogeology. Despite sediment being one of the most common causes of stream impairment in the United States, streambank erosion is not integrated into many surface water management models. In this work, a module is developed to estimate fluvial erosion within an existing surface water optimization model. This model is applied to the Lower Republican River Basin in Kansas to demonstrate the effects of climate scenarios and water management strategies on water shortages and sediment loads. Results indicate water shortage varies most under different water management strategies, whereas fluvial erosion varies most under different climate scenarios. Two sets of parameters characterizing the streambanks (critical shear stress and concentrated flow soil erodibility) were simulated to demonstrate the sensitivity of the results to these values. Results indicate that constraining these parameters is necessary to accurately simulate fluvial erosion, as results not only indicated significant differences in quantities of sediment load for each parameter set but also yielded different optimal management options for each parameter set. This modeling approach provides a computationally efficient method of estimating both water shortages and sediment load within one framework and demonstrates the benefit of considering water shortages and fluvial erosion when making water management decisions.