Crop Water Deficits and their Season-ahead Climate Determinants Across the United States

The agricultural sector in the United States provides an essential food and revenue source and it faces severe challenges due to increasing climate variability, which reduces reliable access to water needed for the crops. Unreliable access to water and the potential for drought result in major economic losses to the sector as well as potentially significant environmental damage. It is thus necessary to mitigate the effects of drought as well as to develop agricultural practices that include preparedness strategies for droughts. To develop these strategies, comprehensive information about droughts must be available early enough to consider before the growing season. To establish such drought information, three major goals and aspects of this research project have been developed. The first was to obtain and process data relevant to the estimation of crop water stress. The datasets include measures of water supply from precipitation, and water demand that is specific to individual crops and weather conditions. The data has been aggregated to a county level for each county in the conterminous United States. The second element of this project was to use the data to construct a crop-specific drought index that incorporates both seasonal variability in rainfall and other weather conditions as well as varying water demand across different crops. The incorporation of crop-specific water demand into the drought index is essential for increased accuracy of the index. The final element was the investigation of climate precursors in terms of their potential drought predictability. The identification of such climate precursors was accomplished through data dependance techniques and the least absolute shrinkage and selection operator (LASSO) approach. These climate precursors will serve as predictors in the eventual development of a season-ahead forecast of the drought index. This index can be utilized by agricultural managers and farmers to optimize practices to best prepare for forecasted periods of drought. Such a forecast will provide useful information in efforts to prepare for and mitigate the effects of drought