Recharge in Desert Regions Around the World
Ground Water Hydrology
Published Online: 15 APR 2005
Copyright © 2005 by John Wiley & Sons, Inc.
How to Cite
Uhlman, K. 2005. Recharge in Desert Regions Around the World. Water Encyclopedia. 5:72–76.
- Published Online: 15 APR 2005
Following Potter's classification, arid and semiarid regions are those whose precipitation to evaporation (P/E) ratios are smaller than 0.5 and between 0.5 and 1.0, respectively. In addition to a lower net precipitation rate, rainfalls are typically infrequent and of short duration; high-intensity seasonal storms contribute a major portion of the annual rainfall over short periods of time. Under these conditions, the shallow soil surface layer infiltration capacity may be exceeded and excess overland flow propagates rapidly to flash flooding. Even low-intensity rainfalls, can lead to significant surface runoff when desert soil crusts have formed.
Water focused and concentrated by topography into ephemeral washes, wadis, sabkhas, and playas provides locations of enhanced recharge in arid areas. A significant component of recharge to arid basin aquifers occurs along mountain fronts. Important aspects along the mountain front include the partitioning of rainfall and snowmelt into surface runoff, deep infiltration along fractures and faults, and vegetation-controlled evapotranspiration. Focused flow along mountain stream channels into the major washes in the Tucson Basin (Arizona) visibly infiltrates flood-plain sediment, and surface water commonly does not leave the watershed. Half the annual recharge of 9 to 10 mm/year to the Ogallala Aquifer in the southern High Plains (Oklahoma and Texas) occurs through playa floors that cover only 6% of the aquifer land surface area.
- arid hydrology;
- desert hydrology;
- vadose transport;
- ephemeral flow;
- isotope tracers;
- aquifer sustainability;
- precipitation to evaporation (P/E) ratios;
- chloride mass balance;