Winter flooding recharges groundwater in almond orchards with limited effects on root dynamics and yield

Abstract

California signed the Sustainable Groundwater Management Act (SGMA) into law in 2014. SGMA requires groundwater-dependent regions to halt overdraft and develop plans to reach an annual balance of pumping and recharge. Groundwater aquifers can be recharged by flooding agricultural fields when fallow, but this has not been an option for perennial crops such as fruit and nut trees. While flooding these crops might be possible during the dormant season, it is not known what impact flooding might have on tree-root systems, health and yield. We followed root production, tree water status and yield in two almond orchards in Northern California for 2 years to test the impact of applying captured winter water runoff for groundwater recharge purposes on tree performance. Results showed that more than 90% of the water applied to sandy soil and 80% of the water applied to loamy soil percolated past the root zones, with no measured adverse effects on tree water status, canopy development or yield. Groundwater recharge did not negatively affect new root production and tended to extend root lifespan. Based upon these data, applying additional water in late December and January is not likely to have negative impacts on almond orchards in moderately drained to well-drained soils.

Transport, dispersion, and degradation of nonpoint source contaminants during flood‐managed aquifer recharge

“…We vary the inundation frequency (Table ), though all simulations receive a total of 0.8 m 3 m −2 of water over 1–14 weeks. This inundation volume was chosen based on published values for flood‐MAR projects on almond orchards in the Central Valley: 0.61–0.76 m 3 m −2 (Bachand et al., 2019), 0.76 m 3 m −2 (Ganot & Dahlke, 2021), and 0.60–0.67 m 3 m −2 (Ma et al., 2022; Murphy et al., 2021). The falling head inundation is too computationally expensive to simulate across subsequent flood‐MAR events.…”

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.…”

Storage variability controls seasonal runoff generation in catchments at the threshold between energy and water limitation

“…Here, we showed that precipitation events that occur during the wet‐up and the dry‐down display characteristics common to water‐limited systems, whereas precipitation events that occur in the plateau display characteristics common to energy‐limited systems. As human population and thus water demand grows, we have started to manage storm flows through practices such as managed aquifer recharge, where we engineer catch basins to purposefully infiltrate stormflow to manually recharge the subsurface (Levintal et al, 2022; Ma et al, 2022). In water‐limited systems, the standard practice is to remove water in times of surplus (Dahlke et al, 2018).…”