Farm-level impacts of prolonged drought: is a multiyear event more than the sum of its parts?

A multiyear discrete stochastic programming model with uncertain water supplies and inter-year crop dynamics is developed to determine: (i) whether a multiyear drought's impact can be more than the sum of its parts, and (ii) whether optimal response to 1 year of drought can increase a producer's vulnerability in subsequent years of drought. A farm system that has inter-year crop dynamics, but lacks inter-annual water storage capabilities, is used as a case study to demonstrate that dynamics unrelated to large reservoirs or groundwater can necessitate a multiyear model to estimate drought's impact. Results demonstrate the importance of analysing individual years of drought in the context of previous and future years of drought.