Precipitation and Evapotranspiration

Abstract

Local water budgets in arid regions are dominated by precipitation and evapotranspiration. Vadose zone interflow is a minor component of local water budgets and typically recharge rates are only a small percentage of rainfall. However, the paucity of vegetation and the occurrence of surface crusts in arid and semi-arid regions results in low soil-infiltration rates, which combined with high-intensity, short-duration convective rainfall, favor runoff. Overland flow, concentrated by topography, converges on wadi channel networks, tends to result in flood flow. Arid lands are, thus, prone to flash floods, which can he highly destructive and frequently result in loss of life. In flat-lying areas virtually all precipitation that falls in inter-channel areas may be lost to evapotranspiration.