The US Department of Agriculture has just released a new report on the impacts of drought on forests and rangelands.   It includes descriptions of the types of drought, impacts on water supplies and vegetation, and includes information on how to deal with the impacts effectively.  You can find it at https://www.fs.fed.us/sites/default/files/DROUGHT_book-web-1-11-16.pdf.

drought and forest report usda 2016