بررسي و تحليل زيست محيطي سد 15 خرداد

Environmental Impact Assessment of 15th of Khordad Dam

The 15th of Khordad dam, with a height of 54.3m is constructed on the Qomrud river, 12km from city of Delijan. It is heterogeneous and has a clay core. Its main purpose is to provide water for downstream farms and drinking water of Qom city. The operation of the dam began in 1996 and two years later its water quality changed. The EC of water increased from I dslm in 1996 to 4dslm in 1999. The possible causes for this variation include recent droughts, thermal stratification, intense evaporation from water surface, entrance of Shur and Darbande- Shur rivers, and chemical reaction of reservoir bed and water. To predict EC changes, Artifical neural network (ANN) is used. Based on weather forecasting, maximum EC in 1997-1998 would be 3.55 ds/m and is 1998-1999 would be 4.05ds/m other environmental effects of this dam include uprising of groundwater, downstream agriculture and social conditions. To improve water quality and reduction of negative effects on environment methods such as reservoir flushing, better management of water quality, diversion of Shur and Darband - Shur rivers from entering the reservoir, prevention of groundwater exploitation in the area, transfer of fresh water from Dezwatershed, and controlling wastewater entrance of Delijan city are proposed.