The study of the effects of dams on the quality and quantity of underground water of detrital fan of the lowest area

After the construction of Torogh Dam in 1984, there was a slump and a high reduction in underground water level in the upper area of Torogh River’s detrital fan. This case is very well observable in the hydrograph of wells in the areas of Khaaje Abaasalt, Ghal’e Sakhtemaan and Mazra’eye Nemooneh. The level of water in these wells has reduced 45, 22 and 21meters respectively in a period of twenty years. Since Torogh’s detrital fan has coarse fragments deposits, it has a high permeability and like other detrital fans, the size of its deposits has reduced from top to the bottom, as a result, its permeability has reduced as well. The permeability of the fragments is ranging from 7.2*10-2 in the top part to 2*10-2 meter second in the base. The reduction of water level has also changed the amount of salts in the water.