ABSTRACT
A rapid growth of coastal cities and industries has put a lot of stress on the groundwater in arid regions. Withdrawal of water from coastal fresh water wells sometimes exceeds the ability of underlying aquifers to replenish the fresh water supply, allowing salt water to seep into fresh water sources. Most of the agricultural development in Sultanate of Oman is concentrated along the coastal strip of the Batinah plain (north of Oman). Due to the total dependence upon groundwater by withdrawal from wells and inadequate surface water recharge, the initial equilibrium of groundwater conditions has been upset with the consequent effect of saline water intrusion. Batinah coastal plain aquifers located close to Barka (west to Muscat) are suffering from huge water deficit and consequently salt-water intrusion is constantly transgressing thereby deteriorating the water quality in wide spread areas.
Treated wastewater can be used in order to combat salt-water intrusion in coastal aquifers like in Barka area. In order to study the technical feasibility of replenishing the groundwater using treated wastewater, the Groundwater Modeling System (GMS) is used that includes MODFLOW in addition to MT3DMS module (Mass Transport Three-dimensional for Multi-Species) for groundwater transport processes. First, a conceptual model for coastal plain aquifers near Barka was developed based on available hydrogeological data. Then, the calibration of the model with steady state flow simulation of the groundwater head distribution for the starting simulation year was conducted. After calibration was made, the model was used to predict water level fluctuations. Similar procedures were followed to simulate seawater intrusion using MT3DMS in order to predict the salinity movement in response to the injection of treated wastewater. Positive responses were observed in terms of improved ground water level and water quality in terms of significant salinity reduction.
