Assessment of quantitative and qualitative indicators of water resources in the Amu Darya Basin, Uzbekistan

The Aral Sea Basin has become a hotspot for several environmental problems due to its geo-location and continental arid climate. In particular, water resource degradation and pollution are major challenges, leading to agricultural losses and reduced productivity. This study assessed the quantity and quality of water resources of Uzbekistan, using retrospective and field measurement data on heavy metal concentrations, long-term river water mineralization, and agricultural runoff obtained from the Hydrometeorological Service Agency, and Ministry of Water Resources of Uzbekistan. In addition, we applied pearson correlation coefficient to better understand how climatic variables influence the mineralization of Amu Darya River (ADR) and drainage water mineralization at different hydrological stations and regions. The findings indicate that the mineralization of Amu Darya River water has escalated from 1.35 to 1.74 times from upstream to downstream. The concentrations of heavy metals, including Cu, Zn, and Cr (VI), have also risen along the river. Copper (Cu) concentrations have increased by an average of 1.1 to 1.5 times, zinc (Zn) concentrations by 1.1 to 2.6 times, and chromium (Cr (VI)) concentrations by 1.1 to 1.8 times. The average annual salinity of collector-drainage water in the Amu Darya River basin varies, with the lowest value recorded at 1.44 g/l in the Surkhandarya region, and the highest value reaching 5.28 g/l in the Kashkadarya region. The average annual volume of collector-drainage water ranges from 4,010 × 109 m3 to 9,283 × 109 m3, carrying approximately 27,769 × 10³ tons of salts, out of a total annual salt load of 19,09 ×103 tons. Overall, the results indicate that water resources are becoming highly mineralized and contaminated with heavy metals in Uzbekistan. These findings highlight the urgent need for policymakers to implement effective measures to mitigate pollution and develop long-term strategies for sustainable agriculture.