Date of Award

6-2020

Degree Name

Doctor of Philosophy

Department

Geological and Environmental Sciences

First Advisor

Dr. Mohamed Sultan

Second Advisor

Dr. Matt Reeves

Third Advisor

Dr. Alan Kehew

Fourth Advisor

Dr. Richard Becker

Keywords

Shallow groundwater, remote sensing, hydrogeology, GIS, statistical geology, hydrology Saudi Arabia

Abstract

Identifying shallow (near-surface) groundwater in arid and hyper-arid areas has significant societal benefits, yet it is a costly operation when traditional methods (geophysics and drilling) are applied over large domains. In this study, we developed and successfully applied methodologies that rely heavily on readily available temporal, visible and near-infrared, radar, and thermal remote sensing data sets and field data, as well as statistical approaches to map the distribution of shallow (1–5 m deep) groundwater occurrences in Al Qunfudah Province, Saudi Arabia and to identify the factors controlling their development. A four-fold approach was adopted: (1) constructing a digital database to host relevant geologic, hydrogeologic, topographic, land use, climatic, and remote sensing data sets; (2) identifying the distribution of areas characterized by shallow groundwater levels; (3) developing conceptual and statistical models to map the distribution of shallow groundwater occurrences; and (4) constructing artificial neural network (ANN) and multivariate regression (MR) models to map the distribution of shallow groundwater, test the models over areas of known depth to groundwater (area of Al Qunfudah city and surroundings: 294 km2), and apply the better of the two models to map the shallow groundwater occurrences across the entire Al Qunfudah Province (area: 4680 km2). Findings include: (1) high performance for the ANN (92%) and MR (88%) models in predicting the distribution of shallow groundwater using temporal-derived remote sensing products (e.g., Normalized Difference Vegetation Index [NDVI], radar backscatter coefficient, precipitation, and brightness temperature) and field data (depth to water table); (2) areas witnessing shallow groundwater levels show high NDVI (mean and standard deviation [STD]), radar backscatter coefficient values (mean and STD), and low brightness temperature (mean and STD) compared to their surroundings; (3) correlations of temporal groundwater levels and satellite-based precipitation suggest that the observed (2017– 2019) rise in groundwater levels is related to an increase in precipitation in these years compared to the previous three years (2014–2016); and (4) the adopted methodologies are reliable, cost-effective, and could potentially be applied to identify shallow groundwater along the Red Sea Hills and in similar settings worldwide

Access Setting

Dissertation-Campus Only

Restricted to Campus until

6-30-2022

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