English abstract
The coastal plain in Sultanate of Oman is the most treasured region for existence of fresh groundwater. Growth of irrigation, urbanization and industrial endeavors have resulted the severe decline of groundwater table in Al Batinah Coastal aquifer especially at Barka leading to enormous seawater intrusion in recent decade. This study aims at the study of the groundwater and solute (Saline water) flow pattern in the southern part of Al Batinah Coastal Plain to stabilize the effects of water deficit in Al Batinah Coastal Region using Groundwater Modeling System. Groundwater flow model MODFLOW along with solute transport model MT3DMS was used to simulate the transient groundwater and saline water flow pattern in southern part of Al Batinah Coastal Plain focusing at Barka area. There wadis namely; Wadi Taww, Wadi Al Maawil and Wadi Bani Kharus were used for the numerical modeling of the study area. Both steady and transient simulation and calibration was carried out using data from Ministry of Regional Municipalities and Water Resources. Water table elevation and groundwater salinity were used as calibration parameters. The calibrated aquifer characteristics such as hydraulic conductivity, specific yield, specific storage, aquifer porosity when 'compared to the previous field studies indicates good agreement. A sensitivity analysis showed that the sensitivity of hydraulic conductivity was high as compared to other aquifer parameters. In Barka region more groundwater was abstracted in response to increased demand from the aquifer storage than being recharged. On average the recharge (36 Million Cubic Meters) was observed to be approximately one-fourth of the abstraction (155 Million Cubic Meters). As a result a head drop of almost 7 m was observed in year 2010 in the coastal aquifer leading to the seawater intrusion to the middle of the coastal plain. The calibrated model was further utilized to simulate two scenarios (1) reduction in pumping rate and (2) artificial recharge with constant pumping. The result from case 1 showed that the reduction of pumping can save up to 66.62 Million Cubic Meters of aquifer storage annually by allowing the natural recharge. Whereas case 2, illustrated that the injection of 150,000 mo/d of reclaimed water can not only defy the seawater intrusion but also raise the groundwater table above the mean sea level. The effect of optimizing the pumping rate and artificial recharge through the model has established the positive response in reduction of seawater intrusion by increasing the water level in the coastal plain. From water management perspective, the technique of artificial groundwater recharged from the reclaimed and surplus surface water is recommended to combat groundwater deficit and to obstruct seawater intrusion in coastal aquifer.
