Streamflow availability ratings identify surface water sources for groundwater recharge in the Central Valley

Abstract

In California's semi-arid climate, replenishment of groundwater aquifers relies on precipitation and runoff during the winter season. However, climate projections suggest more frequent droughts and fewer years with above-normal precipitation, which may increase demand on groundwater resources and the need to recharge groundwater basins. Using historical daily streamflow data, we developed a spatial index and rating system of high-magnitude streamflow availability for groundwater recharge, STARR, in the Central Valley. We found that watersheds with excellent and good availability of excess surface water are primarily in the Sacramento River Basin and northern San Joaquin Valley. STARR is available as a web tool and can guide water managers on where and when excess surface water is available and, with other web tools, help sustainable groundwater agencies develop plans to balance water demand and aquifer recharge. However, infrastructure is needed to transport the water, and also changes to the current legal restrictions on use of such water.The STARR web tool estimates how much and when surplus surface water occurs in each watershed in the three Central Valley basins to help water planners expand groundwater banking.

Increasing Groundwater Availability and Seasonal Base Flow Through Agricultural Managed Aquifer Recharge in an Irrigated Basin

“…Given that winter months are among the highest runoff months, flow reductions of 100 TAF in below normal to wet years (between December and April) are not ecologically significant, since excess flows available for recharge during these months exceed, on average, at least 125 TAF along the Sacramento River (USGS gauge 11425500; Dahlke & Kocis, ; Kocis & Dahlke, ). However, RTV100 D could not be repeated in other subbasins that also impact Sacramento River flows without leading to severe cutbacks in December flows.…”

Optimizing Managed Aquifer Recharge Locations in California's Central Valley Using an Evolutionary Multi‐Objective Genetic Algorithm Coupled With a Hydrological Simulation Model

“…Since C2Vsim operates on a monthly time step we assume that the recharge water is only available for 5 days $${c}_{a}=1/5$$ each month based on statistical analyses done by Kocis and Dahlke (2017). To estimate the corresponding land area needed to recharge the maximum daily volume we assume, based on field experiments and water availability (Dahlke & Kocis, 2018; Ma et al., 2022), that a maximum water depth of 4.52 m (15 ft) ($${c}_{b}=15\,ft$$) can be recharged within the winter rainy season (November‐April). As the hydrologic model is too coarse to capture any spatial variability at a field level, the diverted water is spread proportionally to the element area so that the elements that are receiving diversions from the same diversion node have the same rate.…”

“…Increasing MAR worldwide is an important policy challenge and often starts with identifying suitable locations for MAR facilities. A recent review of MAR site suitability studies (Sallwey et al, 2019) observed that the majority of studies identify suitable sites by combining multiple biophysical factors such as hydrogeology, geomorphology or soil suitability (O'Geen et al, 2015;Russo et al, 2014), land use (Marwaha et al, 2021), but also groundwater quality (Waterhouse et al, 2020), water availability (Dahlke & Kocis, 2018;Kocis & Dahlke, 2017), and economic feasibility (Tran et al, 2019(Tran et al, , 2020a(Tran et al, , 2020b in a multi-criteria decision analysis (MCDA). Marwaha et al (2021), for example, identified MAR sites near rural communities in the southern Central Valley, California by combining soil maps, land use maps, existing conveyance infrastructure information, and general groundwater flow directions in a MCDA.…”

Surface Reservoir Reoperation for Managed Aquifer Recharge: Folsom Reservoir System

“…This requires better understanding how much water is actually available for MAR, considering high peak flows, i.e., flood flows. Few studies have addressed the availability of surface water for MAR in the Central Valley of California (e.g., Dahlke and Kocis 2018;CADWR 2018;PPIC 2018). However, those studies focused on and identified the amount of available water at the large watershed scale and based on historical river flows and water allocation policies.…”