The buffer value of groundwater when well yield is limited

A large proportion of the total value of groundwater in conjunctive use systems is associated with the ability to smooth out shortfalls in surface water supply during droughts. Previous research has argued that aquifer depletion in these regions will impact farmers negatively by reducing the available stock of roundwater to buer production in future periods, and also by increasing the costs of groundwater extraction. However, existing studies have not considered how depletion may impact the productivity of groundwater stocks in conjunctive use systems through reductions in well yields. In this work, we develop a hydroeconomic modeling framework to quantify the eects of changes in well yields on the buer value of groundwater, and apply this model to an illustrative case study of tomato production in California's Central Valley. Our ndings demonstrate that farmers with low well yields are forced to forgo signicant production and prots because instantaneous groundwater supply is insucient to buer surface water shortfalls in drought years. Negative economic impacts of low well yields are an increasing function of surface water variability, and are also greatest for farmers operating less ecient irrigation systems. These results indicate that impacts of well yield reductions on the productivity of groundwater are an important economic impact of aquifer depletion, and that failure to consider this feedback may lead to signicant errors in estimates of the value of groundwater management in conjunctive use systems.