Managed Aquifer Recharge: Potential Component of Water Management in the Syrdarya River Basin
Аннотация
This paper argues that sequential in-channel reservoirs in the Syrdarya River Basin of Central Asia are not sufficient to meet the needs of both upstream and downstream water users. Some of the consequences of the use of in-channel reservoirs include fresh water discharges into the saline depression and flooding of irrigated land in winter and water shortages in summer, which causes low water productivity. This study examines the feasibility of two alternative management strategies (1) building additional off-channel reservoirs, and (2) managed aquifer recharge (MAR). First, the potential for MAR in the upstream Fergana Valley is estimated through a regional assessment of MAR potential, field-scale pilot experiments, and simulation modeling. Second, the potential for MAR is analyzed for lift canal irrigation areas, which cover 70% of the irrigated highlands and the foothills in the river midstream, with a focus on energy use intensity and water and energy productivity. Third, the potential for building off-channel reservoirs and MAR is compared in the downstream portion of the river. Specifically for the Makhtaral Irrigation Project (MIP), a scenario of shifting from lift canal irrigation and groundwater extraction for drainage purposes is compared with groundwater irrigation and MAR. The MIP, located in the tail-end of the transboundary Dustyk Canal, faces waterlogging and salinity issues because of the shallow water table. The study concludes that transboundary cooperation in transboundary water transfers for MAR may increase the amount of water that could be stored underground. Overall, it is shown that there is a high potential for MAR in the Syrdarya River Basin with benefits at both the state and farm levels.