Social Vulnerability to Irrigation Water Loss: Assessing the Effects of Water Policy Change on Farmers in Idaho, USA.

In the Eastern Snake Plain of Idaho, increasing rates of groundwater extraction for irrigation have corresponded with the adoption of more efficient irrigation technologies; higher use and lower incidental recharge have led to increasing groundwater scarcity. This paper assesses farmer vulnerability to a water resource policy that responds to that scarcity by reducing availability of groundwater for irrigation by 4-20%. Using results from a household survey of impacted farmers, we examine vulnerability in two stages, contributing to theorization of farmer vulnerability in a changing climate as well as producing important regional policy insights. The first stage, multimodel selection and inference, analyzes the primary predictors of two forms of vulnerability to groundwater scarcity among this population of farmers. The second stage, a segmentation analysis, highlights policy-relevant variation in adaptive capacity and in vulnerability predictors across the population. Individual-level results indicate that key indicators of vulnerability include several dimensions of adaptive capacity and sensitivity. At the population level, we find that reductions in sensitivity may play an important role in reducing farmer vulnerability. Accelerating global environmental change will require agriculture in arid and semi-arid regions to adapt to shifts in water availability. As water resources shift, institutional contexts and policy landscapes will shift in parallel, as seen with the reduction in groundwater availability in our case study. These institutional shifts may change the face of adaptation and farmer vulnerability in unexpected ways. Our results indicate that such institutional shifts could lean on efforts to enhance farmer adaptive capacity or reduce farmer sensitivity as mechanisms for reducing farmer vulnerability to adaptation policy changes.