Numerical Models for Solving Water Problems of Irrigated Agriculture in South-East Kazakhstan
Abstract
Agriculture, especially irrigated cropping, plays a vital role in Kazakhstan's economy. To address the challenges of forecasting changes in hydrogeological conditions due to irrigation, we employ permanent operational models based on the principles of geoinformation systems and mathematical modeling. We have developed a mathematical model of the Akdalinsky irrigated massif to assess how irrigation impacts environmental components during agricultural development. In developing this model, we used design and operational data from the irrigation system, information on irrigation practices and agricultural activities, results from soil melioration efforts, and long-term hydrogeological observations of groundwater levels and chemistry. The model accounts for vegetation cycles and includes annual updates of input data, geofiltration schematization, and model calibration. It was used to forecast changes in hydrogeological and meliorative conditions under different scenarios, considering irrigation and economic factors. Rice planting schemes have a significant influence on hydrogeological conditions. If the check area doubles between 1988 and 2023, the area with groundwater depths of less than 1 meter will decrease by 25%, while the area with groundwater depths of 3-5 meters will increase by 27.7%. Reducing or discontinuing rice cultivation will push groundwater depths beyond the critical level of 3.75 meters, leading to irreversible land salinization and rendering the land unsuitable for agriculture.