Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Understanding saline water dynamics in coastal aquifers using sand tank experiment and numerical modeling.

Auteur : Al-Yaqoubiyah, Shahad Mattar.

Université de soutenance : Sultan Qaboos University

Grade : Master of Science (MS) in Soil and Water Management 2020

Résumé partiel
Seawater intrusion (SWI) is one of the real threats to groundwater resources around the globe, specifically in highly populated coastal areas as groundwater is heavily exploited. Gaining a better understanding of SWI in coastal aquifers is very important for the efficient and sustainable management of fresh groundwater resources. Saline water dynamic is affected by many hydrological and hydrogeological parameters that include : hydraulic conductivity of the aquifer, recharge rate, abstraction rate, aquifer geometry, geological settings, and density of seawater among others. Many studies have been conducted to address different aspects of SWI using both physical experiments and mathematical (analytical and numerical) modeling. This includes various initial and boundary conditions, and other hydrological settings under different scales. There is no study investigated the dynamics of saline water under managed aquifer recharge (MAR) practice using a sand tank experiment similar to the one presented in this thesis. The main objective of this thesis is to investigate the dynamics of saline water in a coastal unconfined aquifer under MAR practices. The effectiveness of MAR in mitigating SWI was explored under different hydrological conditions that include various values of hydraulic conductivities, hydraulic gradients, injection rates, location of injection wells from the coastline, and depth of injection (well screen). This was achieved using both sand tank experiment and numerical modeling. For the numerical modeling part, a density-dependent flow and transport code, SEAWAT, was selected. Investigating the effect of hydraulic conductivity and salinity concentration using sand tank experiments is challenging and requires tremendous efforts. Hence, numerical modeling is an excellent tool to study seawater dynamics under various conditions because it is cheaper and less time demanding compared with the sand tank physical experiment. A conceptual model that mimics the designed sand tank was developed and calibrated. Sensitivity and grid resolution analyses were performed to ensure the reliability of the developed model when simulating observed sand tank runs and other different scenarios. .

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