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dc.contributor.authorHussain, Mohammed Salih
dc.date.accessioned2016-01-14T12:38:10Z
dc.date.issued2015-10-30
dc.description.abstractSeawater intrusion (SWI) is a widespread environmental problem, particularly in arid and semi-arid coastal areas. Unplanned prolonged over-pumping of groundwater is the most important factor in SWI that could result in severe deterioration of groundwater quality. Therefore, appropriate management strategies should be implemented in coastal aquifers to control SWI with acceptable limits of economic and environmental costs. This PhD project presents the development and application of a simulation-optimization (S/O) model to assess different management methods of controlling saltwater intrusion while satisfying water demands, and with acceptable limits of economic and environmental costs, in confined and unconfined coastal aquifers. The first S/O model (FE-GA) is developed by direct linking of an FE simulation model with a multi-objective Genetic Algorithm (GA) to optimize the efficiency of a wide range of SWI management scenarios. However, in this S/O framework, several multiple calls of the simulation model by the population-based optimization model, evaluating best individual candidate solutions resulted in a considerable computational burden. To solve this problem the numerical simulation model is replaced by an Evolutionary Polynomial Regression (EPR)-based surrogate model in the next S/O model (EPR-GA). Through these S/O approaches (FE-GA and EPR-GA) the optimal coordinates and rates of the both abstraction and recharge barriers are determined in the studied management scenarios. As a result, a new combined methodology, so far called ADRTWW, is proposed to control SWI. The ADRTWW model consists of deep Abstraction of saline water near the coast followed by Desalination of the abstracted water to a potable level for public uses and simultaneously Recharging the aquifer using a more economic source of water such as treated wastewater (TWW). In accordance to the available recharge options (injection through well or infiltration from surface pond), the general performance of ADRTWW is evaluated in different hydro-geological settings of the aquifers indicating that it offers the least cost and least salinity in comparison with other scenarios. The great capabilities of both developed S/O models in identification of the best management solutions and the optimal coordinates and rates of the abstraction well and recharge well/pond are discussed. Both FE-GA and EPR-GA can be successfully employed by a robust decision support system. In the next phase of the study, the general impacts of sea level rise (SLR), associated with its transgression nature along the coastline surface on the saltwater intrusion mechanism are investigated in different hypothetical and real case studies of coastal aquifer systems. The results show that the rate and the amount of SWI are considerably greater in aquifers with flat shoreline slopes compared with those with steep slopes. The SWI process is followed by a significant depletion in quantity of freshwater resources at the end of the century. The situation is exacerbated with combined action of SLR and groundwater withdrawals. This finding is also confirmed by 3D simulation of SWI in a regional coastal aquifer (Wadi Ham aquifer) in the UAE subjected to the coupled actions of SLR and pumping.en_GB
dc.description.sponsorshipMinistry of Higher Education and Scientific Research in Kurdistan Regional Government of Iraq (KRG-HCDP Scholarship program)en_GB
dc.description.sponsorshipBritish Council under Water Security scheme (Project Code: SH- 04509)en_GB
dc.identifier.urihttp://hdl.handle.net/10871/19239
dc.language.isoenen_GB
dc.publisherUniversity of Exeteren_GB
dc.rights.embargoreasonI wish to publish papers using material that is substantially drawn from my thesis (Plans for future publication).en_GB
dc.rightsI wish to place an embargo on my thesis to be made universally accessible via ORE, the online institutional repository, for a standard period of 18 months.en_GB
dc.subjectseawater intrusionen_GB
dc.subjectsimulation-optimizationen_GB
dc.subjectevolutionary polynomial regressionen_GB
dc.subjectsea level riseen_GB
dc.subjectArtificial rechargeen_GB
dc.subjectsaturated-unsaturated flowen_GB
dc.subjectNumerical modellingen_GB
dc.subjectgroundwater managementen_GB
dc.titleNumerical Simulation and Effective Management of Saltwater Intrusion in Coastal Aquifersen_GB
dc.typeThesis or dissertationen_GB
dc.contributor.advisorJavadi, Akbar
dc.contributor.advisorGomez, Diego
dc.publisher.departmentEngineeringen_GB
dc.type.degreetitlePhD in Engineeringen_GB
dc.type.qualificationlevelDoctoralen_GB
dc.type.qualificationnamePhDen_GB


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