A PERSPECTIVE ON DIFFUSE NATURAL RECHARGE MECHANISMS IN AREAS OF LOW PRECIPITATION

Extensive studies document that significant recharge can occur in arid and semiarid climates, even where annual potential evapotranspiration exceeds precipitation. This overview focuses on the importance of considering diffuse recharge mechanisms. The recharge mechanisms discussed include infiltration, redistribution, and evapotranspiration, particularly as they are influenced by climate, spatial heterogeneity, anisotropy, preferential flow, and multidimensional flow. Diffuse recharge, calculated for sites having substantially different geography and soil types, only varies by roughly four orders of magnitude. Temporal variability in recharge is attributed primarily to variability in precipitation patterns, evapotranspiration demands, runoff characteristics, and soil hydraulic properties. Examples of field studies of diffuse recharge emphasize sites in New Mexico.