An example of a complete study of karst hydrogeology (Al Sinn Basin, Syria). II. Hydrodynamic behaviour of the basin

Groundwater in the AI Sinn basin is confined to a carbonate series of Jurassic and Cretaceous age. In the mountainous part of the basin there are more than 200 springs of di scharge ranging from 0.05 dm³/s to 20-30 dm³/s. Three high-discharge springs spout in the coastal part: AI Sinn (8-20 m³/s), Sourit (1-4 m³/s) and Banias (1-3,5 m³/s). Two hydrodynamic horizons are distinguished in the basin: perched water horizon and main aquifer horizon. The numerous small mountain springs drain off the perched water horizon. The three large springs in the coastal plain are fed by the main aquifer. At the beginning of the rainy season (October-November), spring di scharge starts rising with a time lag of 5 to 6 days. Cease of rains (April-May) causes a gradual depletion of spring discharge. In summer, atmospheric condensation replenishes some of the groundwater feeding both the perched water springs and the main aquifer springs. Groundwater level in the main aquifer shows large amplitude variations (up to 200 m). The increasing spring discharge is accompanied by decreasing groundwater mineralization (the latter drops from 700-800 mg /dm³ to 400-500 mg/dm³). The hydrodynamic behaviour of the basin characterizes the area as a purely geosyncline type of karst.