Estimating groundwater recharge using chloride mass balance in the Umm Er Radhuma aquifer (south), Saudi Arabia
Renad Alsufyani
Department of Hydrology and Atmospheric Sciences
The University of Arizona, Tucson, AZ
The recharge rate of groundwater resources provides crucial insights for sustainable water management, ensuring the protection of this vital resource for future generations. My research focused on estimating groundwater recharge using a chloride mass balance (CMB) approach on the Umm Er Radhuma aquifer in the Rub' al Khali area of Saudi Arabia, where a few studies have been conducted. CMB is a practical and cost-effective approach since it depends only on annual precipitation, chloride concentration in that precipitation, and chloride concentration in the groundwater. The result suggests that the average groundwater recharge flux in the Umm Er Radhuma aquifer is 0.567 mm/yr. Given the extremely low estimated groundwater recharge, the region is likely to have high rates of evapotranspiration, limited precipitation, and geology that restricts infiltration. Although this result shows limited recharge, it also presents a favorable opportunity for well-organized and efficient groundwater management planning, particularly since the Rub' al Khali region is sparsely populated, and has significant groundwater supplies that have not yet been fully developed. Since precipitation in Saudi Arabia is infrequent, this estimation was based on a single rainfall event; if we examine more rainfall data, the result may give us a more comprehensive understanding of the long-term trend of groundwater recharge.