Risk assessment and techno-economic feasibility of managed aquifer recharge under high clogging conditions for pasture irrigation: a case study of the Koksu River Basin
This study evaluates the operational efficiency of Managed Aquifer Recharge (MAR) systems utilizing open-type infiltration structures in the Koksu District of Southeastern Kazakhstan. Field investigations conducted between 2022 and 2024 characterized the filtration hydrodynamics and mechanical clogging kinetics within the vadose zone and the underlying gravel–pebble aquifer. Our methodology integrated the use of local surface water and groundwater to provide a high-resolution assessment of recharge performance under authentic hydrogeological conditions. The results demonstrate a significant, multi-stage degradation of infiltration capacity, primarily driven by mechanical clogging. Initial infiltration rates (12.0–6.0 m/day) underwent a sharp decline to 4.1–2.0 m/day within 92 days of operation, eventually plateauing at a critical minimum of 0.8 m/day. This reduction correlates with the accumulation of an 11 mm fine-grained sediment layer, induced by surface water turbidity (18–38 mg/dm 3 ), resulting in a six-fold reduction of the infiltration coefficient. Concurrently, MAR operations facilitated a maximum groundwater rise of 3.1 m, while total dissolved solids (TDS) of groundwater were effectively halved through freshwater dilution, significantly improving water quality. Economically, the implementation of the MAR system increased regional water availability by 20–25%. These findings establish that while the unconfined aquifers of the Koksu Basin possess high potential for seasonal storage, their long-term viability is contingent upon systematic mechanical regeneration. This research provides a robust technical framework for MAR deployment to support livestock watering and sustainable pasture irrigation in arid Central Asia.