Evaluating the effect of supplying drinking water and agriculture water of Sari-Neka aquifer on the salinity movement with the utilization of Gelvard dam

With the fast-growing economy in the coastal regions, the demands for water resources and the exploitation of groundwater have been increased. Consequently, the established balance between freshwater and seawater has been disturbed and hence resulted in extensive seawater intrusion into groundwater. In this paper, the flow model and saltwater intrusion in the Sari-Neka aquifer is simulated using the GMS model. The model is calibrated for four years Between October 2010 and September 2014, both in terms of groundwater levels and TDS concentration. The calibrated model is validated for the next year in terms of groundwater levels and TDS concentration with the available data for October 2014 and September 2015. The values of the correlation coefficient in the steady-state model, transient model and validation model in the flow model are obtained 0/99, 0/98 and 0/97 respectively. The values of the correlation coefficient in the transport model are obtained 0/83 and 0/87 in the transient model and validation model, respectively. After the validated model and assuming all the hydrogeologic conditions remain, a predictive 6-year simulation run indicates that further seawater intrusion into the coastal aquifer can occur in the study area. The effects of the Gelvard dam on the quality of groundwater in the Sari-Neka aquifer in normal, drought and wet conditions also were investigated. The results show that under drought conditions the 50% iso-concentration contour movement for TDS will increase by 5/98 %. In wet conditions, the 50% iso-concentration contour movement will be reduced by 2/94%.