干旱区生态环境知识资源中心

The role of wadi floods in arid zone groundwater recharge has been known and observed for about 50 years in various places worldwide. This phenomenon has been well described, notably in the Walnut Gulch experimental basin, Arizona, USA, and in the plain of Kairouan, Tunisia. After a review of infiltrated water transfer following floods, and of the results of numerous works on transmission losses that permit an estimate of a global average of 40-50% of flood volume lost via the wadi bed, the different recharge stages are described: percolation beneath the wadi, transfer mechanisms in the unsaturated zone, and propagation of the underground mound in the aquifer. The various methods of assessment are reviewed: water balance, piezometric fluctuations, geophysical and geochemical methods, as well as the different models of flood routing-infiltration in wadis. Analysis of case studies show that it is very rare that a simultaneous flood and water table reaction is observed, or that more than one evaluation method is used at the same site. In spite of the considerable number of studies, research and progress achieved in the last 50 years, because of the complexity of the phenomenon, the knowledge is still fragmentary. However, following a new wave of research programmes, and recent multidisciplinary experimentation, further meaningful progress should be rapidly obtained.