Accurate information on agricultural water needs and withdrawals at appropriate spatial and temporal scales remains a key limitation to joint water and land management decision-making. We use InVEST ecosystem service mapping software to estimate water yield and water consumption as functions of land use in Fresno County (a key farming region in California’s Central Valley) during the infamous 2011-2017 California drought. Our calculations show that in recent years, total annual water yield for the county has varied dramatically from ∼0.97 to 5.37 km^3 (all ±17%; 1 MAF ≈ 1.233 km^3 ), while total annual water consumption has changed over a smaller range, from ∼3.37 to ∼3.98 km^3 (±20%). Almost all of the county’s water consumption (∼96% of total use) takes place in Fresno’s croplands, with the discrepancy between local annual surface water yields and crop needs met by surface water allocations from outside the county and private groundwater irrigation. These results, combined with trends away from field crops and toward orchards and vineyards, suggest that Fresno’s land and water management have become increasingly disconnected in recent years, with the harvested area being less available as an adaptive margin to hydrological stress.<br/><br/>Meanwhile, unintended negative ecosystem or social consequences of a particular management scenario can feedback and, in the longer run, negatively impact food production or sustainable water management potential. Here, we showcased how ecosystem services mapping can be used to better integrate land and water resource management through linked analysis of water yield and consumption as functions of land use. Quantifying returns to water and land by crop enables policymakers and consumers to evaluate the trade-offs inherent in agricultural land and water management. Similarly, understanding interannual variation may enable more-substantive direct groundwater recharge efforts during wet years without sacrificing crop productivity. Finally, by identifying economically important but relatively underperforming crops in term of returns to water, we highlight where future research and development efforts might be focused for maximum impact.

Sustainable land management enabled by ecosystem services mapping: Case study on agricultural water use in California’s Central Valley

2019 Fall National Meeting

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