Incorporating Water Management into a Physically- Based Hydrologic Model

Reservoir management decisions are commonly made using surface water models with simplified and/or abstracted physical processes and limited groundwater-surface water interactions. Optimizations with such models might not capture the potential importance of and feedbacks from physical processes such as evaporation and infiltration. This study details how management algorithms of the Water Evaluation and Planning (WEAP) model are incorporated with an integrated hydrology model, ParFlow to simulate reservoir operations for the Upper Klamath Lake in Oregon, USA. ParFlow is a fully coupled physical hydrology model capable of simulating groundwater surface water interactions in heterogeneous porous media. Richards equation is used for variably saturated subsurface flow and the diffusive wave equation is applied for overland flow. The common land model (CLM), which is coupled to ParFlow, simulates land surface processes. Upper Klamath Lake is a large shallow lake with high infiltration rates. Operating policies are highly contentious and must balance the needs of several user groups. Management decisions are evaluated using a variety of multi year simulations and results are compared between the integrated ParFlow model and a simple management model with no physical processes. Differences highlight the sensitivity of management decisions to physical considerations.