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

Abstract

Groundwater aquifers provide an important “insurance” against climate variability. Due to prolonged droughts and/or irrigation demands, groundwater exploitation results in significant groundwater storage depletion. Managed aquifer recharge (MAR) is a promising management practice that intentionally places or retains more water in groundwater aquifers than would otherwise naturally occur. In this study, we examine the possibility of using large irrigated agricultural areas as potential MAR locations (Ag‐MAR). Using the California Central Valley Groundwater‐Surface Water Simulation Model we tested four different agricultural recharge land distributions, two streamflow diversion locations, eight recharge target amounts, and five recharge timings. These scenarios allowed a systematic evaluation of Ag‐MAR on changes in regional, long‐term groundwater storage, streamflow, and groundwater levels. The results show that overall availability of stream water for recharge is critical for Ag‐MAR systems. If stream water availability is limited, longer recharge periods at lower diversion rates allow diverting larger volumes and more efficient recharge compared to shorter diversion periods with higher rates. The recharged stream water increases both groundwater storage and net groundwater contributions to streamflow. During the first decades of Ag‐MAR operation, the diverted water contributed mainly to groundwater storage. After 80 years of Ag‐MAR operation about 34% of the overall diverted water remained in groundwater storage while 66% discharged back to streams, enhancing base flow during months with no recharge diversions. Groundwater level rise is shown to vary with the spatial and temporal distribution of Ag‐MAR. Overall, Ag‐MAR is shown to provide long‐term benefits for water availability, in groundwater and in streams.

Natural and forced soil aeration during agricultural managed aquifer recharge

“…Monitoring soil physical-biogeochemical processes during MAR has been extensively studied (Danfoura & Gurdak, 2016;Ganot et al, 2018;Gorski et al, 2019;Greskowiak et al, 2005;McNab et al, 2009;Rodríguez-Escales et al, 2020;Schmidt et al, 2011;Vandenbohede et al, 2013); however, since Ag-MAR is a relatively new technique in the MAR toolbox, to date only a few studies have monitored these processes in actual agricultural fields during Ag-MAR (Bachand et al, 2014(Bachand et al, , 2016(Bachand et al, , 2019Dahlke et al, 2018;Dokoozlian et al, 1987). Most Ag-MAR studies have focused on developing soil suitability guidelines (O'Geen et al, 2015), regionalscale aquifer storage estimations (Scanlon et al, 2016), water availability analysis (Kocis & Dahlke, 2017), hydro-economic analysis (Gailey et al, 2019), and benefits evaluation using numerical modeling (Kourakos et al, 2019;Niswonger et al, 2017). Among the few Ag-MAR field studies that exist, the soil aeration status, which may impair the implementation of future Ag-MAR projects, has been largely neglected.…”

“…Worldwide recognition of groundwater depletion and its adverse effects on human farmland is flooded using excess surface water in order to recharge the underlying aquifer (Kocis & Dahlke, 2017). As most agricultural fields have lower infiltration capacities compared with dedicated recharge basins, Ag-MAR is designed to capture high-volume excess surface water by flooding large areas of farmland at relatively low recharge rates of less than one meter per Ag-MAR event (Kocis & Dahlke, 2017;Kourakos et al, 2019). Ideally, flooding for Ag-MAR is preferably done on fallow fields or during crop dormancy periods, when agricultural fields have the potential to serve as percolation basins for groundwater recharge.…”

Can Managed Aquifer Recharge Mitigate the Groundwater Overdraft in California's Central Valley?

“…MAR has the potential to replenish aquifers, reduce land subsidence risk, increase drought resilience, and lower flood‐related risks (Chinnasamy et al, 2018; Hashemi et al, 2015; Niswonger et al, 2017; Ronayne et al, 2017; Scanlon et al, 2016). MAR studies in California and elsewhere conducted at the local and farm levels (e.g., Bachand et al, 2014; Dahlke et al, 2018; Ghasemizade et al, 2019; Kourakos et al, 2019) demonstrate the potential of such practices to be scalable to the basin level. Strategies for implementing MAR on a more widespread basis are currently under investigation by CDWR (2018b, 2019).…”

Anthropogenic drought dominates groundwater depletion in Iran

“…By suppling ~ 36% of drinking water and ~ 42% of agricultural water, groundwater is a key freshwater resource globally 1,2 . During the current state of "Anthropocene", groundwater reserves are under enormous stress due to both natural and anthropogenic pressures 3,4 .…”