Our Nation contains regions where agricultural producers contend with an overabundance of water and regions frequently challenged by water scarcity and drought. The 100th meridian is often touted as the dividing line between the wet eastern United States and the dry, water-limited west. While this geographic division serves well as a rule of thumb, it ignores critical factors such as rainfall timing, intensity, frequency and magnitude and resulting systemic impacts. How these events impact water supply in relation to water demand dictates impacts both now and in the future.
Hydrologists often conceptualize water from a budget perspective with inputs (precipitation) and outputs (runoff, infiltration, deep percolation) over a specified land area and time-period. Projected changes in annual precipitation show a latitudinal dipole with increases for much of the northern U.S. and decreases in the drier areas of the southern U.S. These changes could exacerbate the water-related challenges already faced in these areas. For example, an increase in spring precipitation may reduce the number of workable field days, reduce crop yields and disrupt planting operations in wetter regions.