Implications
of Using On-Farm Flood Flow Capture To
Recharge Groundwater and Mitigate Flood Risks Along the Kings River,
CA
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Abstract
The agriculturally productive San
Joaquin Valley faces two severe
hydrologic issues: persistent groundwater overdraft and flooding risks.
Capturing flood flows for groundwater recharge could help address
both of these issues, yet flood flow frequency, duration, and magnitude
vary greatly as upstream reservoir releases are affected by snowpack,
precipitation type, reservoir volume, and flood risks. This variability
makes dedicated, engineered recharge approaches expensive. Our work
evaluates leveraging private farmlands in the Kings River Basin to
capture flood flows for direct and <i>in lieu</i> recharge,
calculates on-farm infiltration rates, assesses logistics, and considers
potential water quality issues. The Natural Resources Conservation
Service (NRCS) soil series suggested that a cementing layer would
hinder recharge. The standard practice of deep ripping fractured the
layer, resulting in infiltration rates averaging 2.5 in d<sup>–1</sup> (6 cm d<sup>–1</sup>) throughout the farm. Based on these
rates 10 acres are needed to infiltrate 1 cfs (100 m<sup>3</sup> h<sup>–1</sup>) of flood flows. Our conceptual model predicts that
salinity and nitrate pulses flush initially to the groundwater but
that groundwater quality improves in the long term due to pristine
flood flows low in salts or nitrate. Flood flow capture, when integrated
with irrigation, is more cost-effective than groundwater pumping