The possibility of using groundwater and collector-drainage water to increase water availability in the Maktaaral district of the Turkestan region of Kazakhstan

The Turkestan region in the southern part of Kazakhstan is currently facing a water scarcity issue due to various factors. These factors include the declining transboundary flow of the Syr Darya River, the effects of climate change, the increasing population, and the economic growth of neighboring countries in Central Asia. The water availability of the operating irrigation systems in the region fluctuates between 75 % and 95 %, dropping to 50–60 % in dry years, leading to a significant shortage of water resources. In particular, the agro-industrial complex, the largest water consumer, is heavily affected, with over 80 % of available water resources needed for irrigation. Therefore, this research aimed to investigate the potential use of groundwater and collector-drainage water to enhance water availability in the Maktaaral district of this region. The research methodology consisted of analytical and experimental studies to examine the formation and contribution of groundwater to total water consumption based on its depth and to determine the qualitative composition of collector-drainage water for reuse in irrigation. The study results indicate substantial losses of irrigation water due to filtration in the region, leading to a significant rise in the groundwater table. Consequently, the area of irrigated lands with groundwater depths up to 1 m (hydromorphic regime) in the Maktaaral district increased from 105 ha in 1994–378 ha in 2002 and to 2562 ha in 2021, representing an 18-fold increase. Under these conditions, the contribution of groundwater to total water consumption was 74 %, with irrigation water accounting for 26 %. In areas with a semihydromorphic soil regime where the groundwater table varies within 2–3 m, the volume of groundwater consumption decreased, amounting to 51 % of the total water consumption. Moreover, under the automorphous soil regime, where the groundwater table is greater than 3 m, the total water consumption was fully supported by irrigation water. Research on the qualitative composition of collector-drainage water in the Maktaaral district revealed a predominance of toxic salts (74.3–76.6 %), indicating that their use for irrigation would lead to soil salinization and alkalinization. The reuse of these waters is feasible only through mixing them with irrigation water to reduce salinity and increase the volume of suitable water resources for irrigation. However, regular monitoring of the chemical composition of such waters is essential.