Modeling Groundwater and Return Flow in an Integrated Framework to Investigate the Resilience of U.S. Water Resources in the Future

To advance understanding of the interactions between human activities and the water cycle, an integrated terrestrial water cycle component has been added to an Earth system model. This includes a land surface model fully coupled to a river routing model and generic water management model applicable globally at 1/2^o resolution and regionally at 1/8^o resolution. A global integrated assessment model and its regionalized version for the U.S. are used to simulate water demand consistent with the energy technology and socio-economics scenarios. Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. As groundwater provides an important source of water supply for irrigation and other uses worldwide, the integrated modeling framework has been extended to represent groundwater as an additional supply source, and to account for the return flow generated from the groundwater and surface water withdrawals.

In this presentation, we evaluate the groundwater supply and return flow modules by analyzing the simulated regulated flow, reservoir storage and supply deficit for irrigation and non irrigation sectors over major hydrologic regions of the conterminous U.S. The modeling framework is then used to provide insights on the resilience of future water resources in the U.S. ensured specifically by the return flow and groundwater dependence.