Assessing Groundwater Quantity and Quality Variations in Arid Regions Due to Climate Changes and Anthropogenic Factors: Case Study Saudi Arabia

In the Kingdom of Saudi Arabia (KSA), water resources are limited in hyper-arid regions, which are dependent on groundwater (88 percent), desalination water (8 percent) and wastewater treatment (4 percent). The management and development of these resources are essential to sustain population growth and grow the agricultural, industrial, and tourism sectors. Since the groundwater is the most valued water resource in the country, the majority of researchers are focused on the water quantity and water quality in this region in order to find the best solution to face this issue. In 1953 the Ministry of Agriculture and Water was established and assigned the mission of identifying and managing the water resources, aiming to ensure their maximum efficient development and use. The economic future of the Kingdom and the survival of the its people depend alike on the availability of water, its prudent use, and its rational development through long-term program that aim to help fulfill the overriding goal of the government, which is to establish and maintain a better life for the people of the Kingdom. Previous researchers have focused on the groundwater resources in the Saq aquifer region in northern KSA, where the depletion is the highest, during the past 10-20 years. However, most studies focused on groundwater quality, and not quantity, which is very important in the monitoring and management of water resources, but one the other side monitoring these resources are significant to sustain and develop our resources. Since the Kingdom does not have a robust database for continuous monitoring groundwater, it is critical to find appropriate scientific methods to monitor the groundwater permanently that can be used to give us a big picture in the present time and in the future to deal with this issue. Therefore, the overall objective of this dissertation was to design suitable methods for an integrated monitoring mechanism of the groundwater quantity and quality using geophysical and geochemical information of the aquifers and their water resources, hydrologic modeling, satellite Remote Sensing data, and Geographic Information systems (GIS). In order to achieve this, I combined laboratory analysis of water quality variables with modeling of the water resources patterns, and validated the findings with field-level water use and withdrawal data, to develop a suitable scenario to monitor groundwater in this region continuously. The work has been described in the following three manuscripts, as per the Graduate School Manual guidelines: MANUSCRIPT І (published in Hydrological Processes 2017). The objective of this work was to utilize month-to-month (April 2002 to April 2015) GRACE (Gravity Recovery and Climate Experiment) data as well as applicable geologic, hydrologic, and remote sensing datasets to inspect the spatial and temporal variations in GRACE-derived terrestrial water and groundwater storage over the Saq aquifer system and to research the components (i.e., natural and anthropogenic) controlling these varieties. This study extends the investigation of the individuals who have already utilized GRACE data to monitor the Saq aquifer region (e.g., Sultan et al., 2013) by (1) using enhanced state of the art GRACE global mass concentration solutions (mascons), (2) using yields from an improved global land surface model, Global Land Data Assimilation System (GLDAS), to isolate the groundwater storage, (3) developing the area of the study zone to incorporate the Saq aquifer in the KSA and Jordan, and (4) Broadening the time traverse utilized by Sultan et al., (2013) by three years. MANUSCRIPT ІI (Submitted to Journal of Hydrology). In this manuscript, we developed and applied an integrated approach to quantify the recharge rates of the Saq aquifer system. Given the areal distribution of the Saq transboundary aquifer system, the interaction between the Saq aquifer and the overlying aquifers was also assessed. Specifically, we set out to accomplish the following: (1) examine the areal extent of the Saq aquifer recharge domains using geologic, climatic, and remote sensing data; (2) investigate the origin of, and modern contributions to, the groundwater in the Saq aquifer system by examining the isotopic compositions of groundwater samples collected from, and outside of, the Saq aquifer; and (3) estimate, to first order, the magnitude of modern recharge to the Saq aquifer utilizing data from the Gravity Recovery and Climate Experiment (GRACE) and applying the continuous rainfall- runoff model, the Soil and Water Assessment Tool (SWAT). MANUSCRIPT ІII (being prepared for Groundwater journal). The objective of this Chapter is to quantify the groundwater quality of the studying area by measuring the ionic compositions, the characterization of the water quality and radioactive materials by collecting samples and comparing the results with the Water Health Organization of drinking water. Since the Kingdom of Saudi Arabia does not have a continuous water quality control system, it is essential to check the groundwater quality in the study area and make sure it is suitable for drinking and domestic uses. In addition, comparing the previous data in the same studying area with the present data to identify the differences in the groundwater quality data in between the two periods, and understanding the factors controlling the groundwater salinity and total dissolved solids distribution in order to minimize the overexploitation of freshwater resources and to maintain the livelihood of the population and public health. In conclusion, groundwater monitoring includes both groundwater quantity (e.g., groundwater level and recharge rates) and quality monitoring (analysis of selected physical and chemical variables). The purposes of groundwater monitoring are to manage and develop the policy of the groundwater resources and to predict the groundwater quality and quantity due to natural processes and human impacts in time and space. Therefore, in this situation we need to have a useful database for assessment of the current state, anticipating changes and forecasting trends in the future. My results in this dissertation will contribute to the effective and efficient utilization of the Saq aquifer water resources and will be used to promote the sustainable development of the Arabian Peninsula and Middle East’s natural resources in general. The findings have been and will be shared with stakeholders and decision makers in relevant governmental agencies to develop viable management scenarios for the water resources of the Saq aquifer