The Hydraulic and Environmental operation for the Main Outfall Drain, Ad Dalmaj Lake and Al Hammar Marsh System


Iraqi Marshlands which are located within the southern part of Iraq were driedafter 1991. The dried marshes were re-flooded after year 2003. Because of theshortage of water that feeds the marshes during the last years, these marshes beganto dry again. Therefore, finding new feeding sources became very necessary matter.The Main Outfall Drain, MOD, is suggested to be one of these sources to feed AlHammar Marsh during the dry water years. Ad Dalmaj Lake which is locatedupstream of Al Hammar Marsh is mainly feeding by the MOD water and then theoutfall of this lake is discharge again into the MOD. Therefore, the hydrologicaloperation of this lake and then the quantity and quality of the outflow water fromthis lake into the MOD affected the water quality of Al Hammar Marsh when usingthe MOD water to feed the marsh.A hydrological and water quality routing model was prepared based on massconservation low, mass balance model, and two scenarios were applied for AdDalmaj Lake feeding, constant inflow with variable outflow and constant outflowwith variable inflow, based on the incoming and outgoing discharges. Eachscenario includes six cases of lake maximum inundation area; 100%, 90%, 80%,70%, 60% and minimum inundation. For each case the inundation area varied withrespect to the ET0 variation from minimum area during the month of maximum ET0to maximum area, of this case, during the month of minimum ET0. TDSconcentration was used as a measure of the salinity of the water because it fairlyindicates the level of salinity problem. The variation of inflow and outflowsdischarges, water level, lake and marsh area, storage volume, and the water salinitywithin the lake and marsh wereResults of applying these models with these flow scenarios and inundationcases show that the water salinity within Ad Dalmaj Lake and Al Hammar Marshwas out of the acceptable range of international standards for most of the studiedcases. While for other cases it was unpalatable for drinking, several restrictionsmust be imposed when used for irrigation to prevent salts effects on crops, soil, andground water, and not acceptable for livestock and unfit for poultry in most of themonths during two operation years and in some months in the beginning of the firstyear, the water can be used for growing livestock and poultry.