Integrated Groundwater-Surface Water Modeling and Application for Integrated Resource Planning

    Brian Heywood CDM Smith Inc., 2295 Gateway Oaks Drive, Suite 240, Sacramento, CA 95833

Brandon Nakagawa, San Joaquin County, California

Rehad P. Hossain, CDM, Inc.


San Joaquin County has experienced record growth in recent years, with its current population projected to more than double by 2040. With the major rivers running through the County largely appropriated, agricultural, and increasingly urban water users are relying heavily on groundwater. This reliance on groundwater has resulted in significant overdrafting of the groundwater basin, which, in turn, is causing saline water intrusion.

San Joaquin County developed an Integrated Water Resource Management Plan to improve the sustainable management their water resources. This Plan identified projects to increase the availability of water in the County for agricultural use by enhancing groundwater recharge and storage.

A key component of evaluating the impact and benefit of implementing these projects is the application of a fully integrated groundwater-surface water model. The groundwater model was initially developed to improve the understanding of the County’s groundwater resources, in particular the nature and severity of the groundwater overdraft. This poster illustrates the application of the 3-dimensional model, and how the model simulates the interaction between groundwater and surface water, including all major rivers and diversions, land use, agricultural water demands and return-flows.