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Sultan Qaboos University (2003)

Impact of Treated Wastewater Recharge in Salalah Costal Aquifer on Groundwater Quality

Qatan Ahmed

Titre : Impact of Treated Wastewater Recharge in Salalah Costal Aquifer on Groundwater Quality

Auteur : Qatan Ahmed

Université de soutenance : Sultan Qaboos University

Grade : Master Civil and Architecture Engineering 2003

The city of Salalah is located on the southern coast of the Sultanate of Oman. The city is in the center of a coastal plain, which extends from the foot of Jabal Al Qara to the Arab Sea and from the coastal town of Taqah in the east to Raysut in the west. Groundwater is the only source of water supply for the domestic and agricultural communities in the area. The abstraction rate from the aquifer has gone beyond the annual recharge rate thus reducing freshwater storage and allowing the saline water intrusion in the coastal area. Several studies targeted this problem in an attempt to find feasible solutions. One of those proposed solutions was to inject treated wastewater collected from the city of Salalah into the coastal aquifer to create an elevated head to avoid further deterioration of water quality by salinity. The implementation of this solution is currently in progress. A series of recharge wells were constructed in the agriculture strip near the coast and Garziz farm to the upstream near the Salalah wellfield. These wells will receive treated wastewater from the Salalah treatment plant through a pipeline. The present project aims at the study of the impact of treated wastewater injection into the coastal aquifer of Salalah on the upstream groundwater quality, and the effectiveness of the treated wastewater recharge in controlling the advancement of saline water into the fresh water in the Salalah coastal.aquifer, In the present study MODFLOW, a three-dimensional groundwater model-Tor flow through porous medium, is used. The model is a well-known finite difference package developed by McDonald and Harbaugh (1982). In -addition to that a Mass Transport Three-dimensional for Multi-Species (MT3DMS), is a three-dimensional transport model for the simulation of advection and dispersion of dissolved constituents in groundwater systems. Those models are utilized as part of the Department of Defense Groundwater Modeling System (GMS), which provides a graphical user interface’ for performing groundwater simulations. Initially MODFLOW was calibrated in steady state against observed water levels in 1990 then calibrated in transient state against the observed water levels from 1990 to 2000. The results of the study showed that the proposed project of injecting treated wastewater into the coastal aquifer will be effective in controlling seawater intrusion. But the upstream groundwater quality will be adversely affected by the treated wastewater injection near the Garziz farm after 2020. The study recommends not to operate the eight recharge wells near the Garziz farm for the injection of treated waste water into the aquifer.


Page publiée le 12 mars 2016, mise à jour le 4 novembre 2017