National Drought Mitigation Center

Geography and Drought

  1. Frequency and duration of severe drought decline from the west edge of the semiarid region to the east edge of the sub-humid region.
  2. Total days during which preferred plant species are likely to grow rapidly (recovery) each year decline as average annual rainfall and length of growing season decline.
  3. Northward increases in day length and concentration of precipitation during the frost-free period and declines in evaporation result in similar or greater levels of herbage production within the same precipitation zone.