thesis Title: Utilizing Treated Wastewater for Groundwater Recharge in Al-Batina Coastal Plain Groundwater is the main conventional water resource in Oman. Agricultural activities consume most of the groundwater in Oman (almost 78%). In the last two decades, the salinity intrusion issue became a serious threat on the future of water resources in the country. This research aims at studying the effect of utilizing treated wastewater to compensate the shortage in the groundwater aquifer and to mitigate the problem of the salinity in the coastal areas of Al-Batina Governorates. The Groundwater Modeling System (GMS) software was used to simulate the water level in the study area (Barka coastal area). Data from the Ministry of Regional Municipalities and Water Resources for the period from 1984 to 2008 were used in this simulation. The results showed good agreement between the computed and the observed heads. The model was then used to simulate the required quantities of the treated wastewater to be recharged into the groundwater aquifer to help in raising the water level and hence defy the sea water intrusion, using two options of the recharging concepts. The first concept was to inject around 110,000 m2/d in a strip of 7.2 x 3.4 km from the treated wastewater into the groundwater aquifer. The results indicated that the available quantities of wastewater produced in the study area (20,710.m®/d) are not enough to defy the salinity along the coastal line of the study area. The second concept was to save around 30% of the groundwater consumption by suggesting alternative types of crops that consume less water, or by adopting modern irrigation systems that help in water conservation. The simulated model was also used to estimate the time required for the recharge process to increase the water level in the study area. It was found that more than eight years are required to achieve this target. It is recommended to conduct further experimental studies in Al-Batina to verify the model results practically. It is also recommended to use the treated wastewater directly to irrigate the agricultural crops. However, groundwater recharge with treated wastewater can be used for surplus quantities. Moreover, a social survey study was conducted to investigate the public awareness about the wastewater treatment processes and public impression towards the utilization of treated wastewater for different options. The survey results showed a lack of awareness in the public knowledge about the wastewater treatment processes and technologies. Most of the respondents preferred to use the treated wastewater for landscaping. This study recommends that the wastewater service companies increase their effort to enhance the public awareness and publicize the reuşe of the treated wastewater in more beneficial applications