California’s recent drought has exacerbated the depletion of surface water supplies, accelerating groundwater overdraft, and reducing hydropower production from the surface water reservoirs. California’s inter-tied water and energy systems always seek enhanced drought forecasts and robust adaptation strategies to address these challenges. The concept of flood flows for Managed Aquifer Recovery (Flood-MAR) is a promising option to refill depleted underground water storage during drought periods. This study will exploit the previously developed simulation and optimization models and devise a new, improved decision tree-based calendar (DtC).  Within the mission set by the Sustainable Groundwater Management Act (SGMA), this project protocol will integrate the climate extremes with hydropower, land use, and water management strategies. A hybrid optimization model is proposed to set explicit decision-making rules for better economic benefits in need of the tradeoff between energy production and maximum water storage in the system. In this regard, the objectives of this research include:

This task concentrates on economic analysis of drought implications employing the existing statewide hydro-economic model, CALVIN (California Value Network). This research modifies the inter-tied California Water Network by adding one recharge facility and one diversion point near the American River below the Nimbus Dam. The primary objective of this facility is to get the benefit from artificial recharge by the community below the downstream of the American River (Figure 1). A portion of the statewide water network entailing the proposed recharge facility, which directly connects to the groundwater storage facility, is shown in Figure 2.

This study relies on existing hydrology from 1921-2003 and 2050 land use data and urban population to minimize water allocation costs.  In addition to one diversion node and recharge facility (Figure 2), we penalized both the surface water and groundwater ending storage by $900 per acre-feet and $100 per acre-feet to remove the ending storage constrained at storage facilities so that there is an increase in the groundwater storage as a part of the Flood Managed Aquifer Recharge program without impacting hydropower generation and Delta outflow.

This study makes usage of different CALVIN runs Recharge-LF and Recharge-PF ( after adding recharge facility and diversion point, Figure 2) together with Base Case (before recharge facility). While LF refers to limited foresight, PF refers to perfect foresight run sticking to the base case with perfect foresight runs. Preliminary results, till now, show:

• Increased surface water storage (Figure 3)
• Increased hydropower and hydropower revenue from October to March (Figure 4)
• Increased groundwater storage (Figure 5, top)
• Increased groundwater pumping in dry years (Figure 5, bottom)

Figure 3: Surface water storage behind the Folsom Lake before (base case) and after recharge g=facility (Recharge-LF and PF) under different water year types. LF refers to limited foresight run and PF to perfect foresight run.

Figure 4: Average hydropower generation, MW/year (top) and hydropower revenue, M$/year under different water year types for different scenarios, including base case.

Figure 5: Top: Groundwater storage and bottom: groundwater pumping in different water year types for different scenarios.

The future analysis includes a complete and detailed analysis of the system, and they are agricultural water delivery, Delta Outflow, system operating cost, and scarcity cost. In addition, this study will be expanded towards sensitivity analysis with different configurations, climate change scenarios, and land-use decisions.

Collaborators

Dr. Josue Medellin-Azuara – UC Merced

Dr. Erfan Goharian – University of South Carolina

Dr. Dennis P. Lettenmaier – UCLA