Four distinctive but poorly documented landforms in the Badain Jaran megadunes were studied: arcuate steps, multi-stage fans, depressions formed by runoff erosion, and groundwater overflow zones around lakes. The development of these four landform types indicates the following: (1) The hydrological balance in the sand layers of the megadune areas is positive; (2) After evaporation and transpiration, precipitation is able to infiltrate the deep sand layers; (3) Precipitation is a source for the groundwater and for many of the lakes of the area. The groundwater recharge mechanism is characterized by intense precipitation events that provide a water source, high infiltration rate, shallow evaporation depth, and low water retention. These factors together enable the precipitation to be transformed into groundwater. The energy of gravity water and the high water film pressure of adsorbed water together provide the forces necessary for effective water recharge.
Slip distribution of the 2003 Boumerdes-Zemmouri earthquake, Algeria, from teleseismic, GPS, and coastal uplift data
