Groundwater Sustainablity in the Central Valley

A major concern for California water resource management is the sustainability of the Central Valley groundwater aquifer. In this app you can investigate how groundwater levels have changed since 1980, and use the Groundwater Depletion Model [Massoud et al., In prep], to assess how groundwater availability in the future changes under different user-defined water management scenarios. The default case presented is the "business as usual" scenario, where no management changes are made. Using the slide bars on the right, you can create different management scenarios and test the impact on future groundwater levels.

Groundwater in the Central Valley

Precipitation is the independent variable used to drive the model. Precipitation data are empirically related to each supply and demand variable in Central Valley water management portfolio (and thus the amount of groundwater supply) for each year. Additionally, precipitation also impacts the recharge of the aquifer. Shown below is precipitation for each year of the study used to drive the model (1 indicates an average year, less than 1 is a dry year (red), and greater than 1 is a wet year (blue)).

Precipitation ratio compared to average

During wet years, greater precipitation increases surface water availability and reduces the need for groundwater. Furthermore increased precipitation recharges to the aquifer thus groundwater levels increase. During dry years the opposite occurs, especially in the case of consecutive dry years occur, reduced precipitation decreases surface water availability and increases reliance on groundwater to meet demands therefore groundwater levels decreases. Shown below are the model simulated changes in groundwater for each year; in blue are the wet years and in red the dry years, from precipitation observations presented above.

Simulated Changes in Groundwater Levels

Shown below are the observed changes in groundwater levels, USGS (1981-2003) and GRACE (2004-2013). Again, blue are from wet years and red dry years defined from precipitation.

Observed Changes in Groundwater Levels

1. Choose time period

2. Chose unit system

3. Try different management scenarios

Water Demand
Water Supply

Simulations are based on the empirical model presented in the paper: Quantifying groundwater sustainability in California’s Central Valley – An empirical method to estimate and project groundwater depletion and recharge (Elias C. Massoud, Adam J. Purdy, Michelle Miro, Sofia Hallerbäck, Jasper A. Vrugt, and James Famiglietti)