Evaluation of PMWIN Model in Dropping Water Table in the Margin Of Interceptor Drain of Qazvin Salt Marsh

Given the important role of groundwater resources in the regional water demand، evaluation، simulation and management of groundwater is important. Qazvin plain is bowl-shaped and due to approaching marl formation near to the ground surface at the plain terminal point، it can not be considered as a suitable outlet. Rising of groundwater level and marshy soil in the output of Qazvin Plain is one of the major problems of salt marsh edge. In national plan of salt marsh lands drainage in Qazvin in order to decrease the water table and to prevent the progress of salinity، An interceptor drain with Hydrulic structures have been constructed with a length of 30 (km)، and 99 observation wells، in the direction perpendicular to the drain is constructed in 9 sections. By using monthly water table data in this wells and hydraulic behavior simulation of aquifer of changes water table by using PMWIN model، drain performance on reduce of the water table has been checked. Statistical indices of RMSE=0. 622، MAE=0. 476، SEE=0. 238، R2=0. 85 and error variance of total stress period of 0. 127 are all indicating the accuracy of model output. According to the contain results، decrease of water table up to 60 (cm) of ground surface، leading to reduce of the soil salinity progress that shows drain performance has been quite satisfactory.