Title:Mountain system recharge to the deep aquifers in sedimentary basins of South Kazakhstan, Central Asia
Speaker: Dr. Vadim Yapiyev, Senior Researcher, National Laboratory Astana, Nazarbayev University
Abstract
Groundwater resources in lowland areas of arid and semi-arid regions can originate from distant mountain ranges. In Central Asia, the mountain cryosphere often acts as a “water tower” for populations living in intermountain valleys and lowland plains. Little is known about groundwater and its recharge processes in Central Asia’s sedimentary basins despite its importance.
In this study, the integration of stable isotope and hydrochemical data with geological information and radiocarbon dating of waters from aquifers ranging from 100 to 3,000 meters deep in South Kazakhstan’s eastern sedimentary basins has led to the development of a comprehensive groundwater recharge model. Low salinity (< 1.5 g/L) and very negative δ18O values (-12 to -16 ‰) in most of the deep groundwaters imply that the aquifers are replenished by Mountain System Recharge (MRS) mechanisms rather than previously thought proximal sources.
Extremely low modern local precipitation (e.g., <200 mm/year), its stable isotope composition, and high evaporation rates suggest an unlikely contribution from contemporary recharge to deep groundwater aquifers. Our data confirm the potential for deep, long-distance recharge, dominated by lateral flows from mountain regions hundreds of kilometres away. Groundwater ages ranging from 21,000 to 35,000 years further support this recharge pattern, linking it to the Last Glacial Period and long-term infiltration processes.
The compelling evidence of extremely slow groundwater replenishment, spanning thousands of years, in the lowlands of Central Asia underscores the need for careful management of this valuable, non-renewable resource.
Short bio
Dr. Vadim Yapiyev is an Earth and Environmental scientist with over 10 years of academic experience, specializing in water resources research in Kazakhstan and broader Central Asia. His current research focuses on Critical Zone and Land Surface Processes, specifically how climate (change) impacts water and land in the region. He has authored and co-authored more than 20 peer-reviewed publications, including a book chapter on groundwater in the Aral Sea Basin.