Report for 2001GA4701B: Agricultural Drought Assessment and Forecasting for the Southeastern United States

The water resources systems of the Southeastern U.S. are increasingly stressed by various demands. This stress is magnified during the periodic periods of drought that occur in the region, and agriculture is particularly affected by these droughts. Recent public policy has attempted to mitigate the impacts on farmers, but reliable methods of drought assessment and forecasting are needed to allow efficient policy implementation. A methodology is presented to assess the effects of droughts on crop yields, irrigation demands, and the full yield-irrigation relationship. The technique utilizes irrigation optimization algorithms coupled with physiologically based crop models. Ensembles of climatic forcing allow for quantification of the stochastic crop-water production function at specific sites and quantification of the changes in this function in drought periods. Data needs for assessment are discussed as well as sensitivity of the methodology to some input parameters. The technique is applied to four case study sites in southwestern Georgia, and potentially useful information is derived. Options for drought forecasting are briefly discussed.