Abstract
Quantitative assessment of natural groundwater recharge is essential for sustainable groundwater management in arid regions, including western Kazakhstan, where freshwater lenses within sanddune aquifers provide drinking water, water for technical uses, and livestock watering.Reliable recharge estimates also support assessments of aquifer resilience to climate change and drought.This study estimated recharge to the Western Kyzyl-Kum freshwater lens using the chloride massbalance (CMB) method, combining five years of precipitation chloride data with groundwater chemistry from spatially distributed monitoring wells.To avoid unequal temporal weighting, annual atmospheric chloride fluxes were averaged over 2020-2024, while repeated groundwater measurements were summarized at the well level before spatial averaging.A mean groundwater chloride concentration of 204.9 mg/L yielded a first-order recharge estimate of approximately 80.63 mm/year, equivalent to gross recharge of approximately 5.83 × 10 6 m 3 /year over the 72.4 km 2 assessment area.This estimate is conditional on atmospheric deposition being the dominant chloride source and should not be interpreted as sustainable yield.The findings demonstrate the potential of the CMB method to inform groundwater management in arid sand-dune aquifers, provided that sitespecific chloride sources and hydrogeological conditions are critically evaluated.