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Colorado State University (2019)

Fresh groundwater lenses in the Arabian Peninsula : formative, stability and management assessments

Bailey, Ryan

Titre : Fresh groundwater lenses in the Arabian Peninsula : formative, stability and management assessments

Auteur : Bailey, Ryan

Université de soutenance : Colorado State University

Grade : Doctor of Philosophy (PhD) 2019

Résumé partiel
The formation of fresh groundwater lenses (FGLs) overlying denser, saline or brackish groundwater is a fascinating hydrologic phenomenon that creates groundwater supplies of great potential value for humans and ecosystems in several formation settings, such as coastal areas, atoll islands, riverine floodplains, and subterranean oases in arid regions. In particular, FGLs in subterranean oases are a critical source of freshwater supply in arid regions, due to a general lack of perennial rivers and lakes. These FGLs are in danger of salinization due to natural events and anthropogenic stresses. Although extensive research has been conducted on FGLs in general, the FGLs in subterranean oases in arid regions have received less attention. Key knowledge gaps include the quantity and frequency of natural recharge to these FGLs ; reliable estimates of environmental aquifer dispersivity at the scale of subterranean FGLs ; the timing of lens development ; and the impact of anthropogenic activities on lens dynamics. This dissertation focuses on the FGLs of subterranean oases in the Arabian Peninsula (AP), using the Rawdatain FGL in Kuwait as a case study. Among the FGLs in the AP, the Rawdatain FGL in Kuwait is perhaps a unique candidate because of its size and the availability of extensive subsurface data for the pre-development period. The main objectives of this study are as follows : (1) estimate long-term average annual recharge for the Rawdatain FGL and investigate the timing of lens depletion due to climate change ; (2) provide a realistic range of longitudinal (αL), horizontal transverse (αh), and vertical transverse (αv) dispersivity values for the aquifer ; and (3) assess the impacts of historical and future anthropogenic activities and evaluate artificial recharge alternatives for lens recovery storage (LSR). In this study, a 3D density-dependent groundwater flow and solute transport model using the SEAWAT modeling code is developed using the following pre-development period calibration targets : (1) groundwater head, (2) spatially-variable total dissolved solids (TDS) groundwater concentration, (3-5) three groundwater volume targets, (6-8) three vertical thickness targets of stored groundwater of three different water quality TDS ranges (0−700, 700−1000, and 1000−2000 mg/L), and (9) geometrical shape features of the lens along cross-sections. In addition, groundwater age data of the Rawdatain FGL was used as an independent factor to constrain the dispersivity and recharge rate during the simulated period of lens development.

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Page publiée le 19 octobre 2020