ABSTRACT

The water balance procedure is widely used by geographers, hydrologists and climatologists in teaching, research and applied water-resources planning, particularly in agricultural applications. The water balance combines precipitation and evapotranspiration for specific time periods and evaluates the effects on soil moisture storage and runoff. The procedure for water balance does not differentiate between surface runoff and groundwater runoff, though it is possible to differentiate runoff from snowmelt. The author limits the discussion to a monthly water balance. The terms 'wet season' and 'dry season' refer to periods defined by the relative magnitudes of precipitation and potential evapotranspiration. When precipitation exceeds potential evapotranspiration it is considered the wet season and vice versa for the dry season. Water balances for even drier climates have larger deficits and lower soil moisture levels. The water balance procedure brings together many of the components of the hydrologic system into a single unified analysis. The procedure has minimal data requirements which makes it easy to apply.