Spatiotemporal heterogeneity of hydrochemistry and runoff composition, and their responses to environmental elements in the Alpine inland river basins of Central Asia

The alpine inland basins of Central Asia (AICA), China We obtained hydrochemical and stable isotope monitoring data for multi-water type samples (including river water, shallow groundwater, glacial meltwater, snow meltwater, and precipitation) over three years to systematically explore the regional spatiotemporal heterogeneity of hydrochemistry and the runoff composition in the AICA and their responses to environmental elements. (1) Significant spatiotemporal heterogeneity of total dissolved solids (TDS), ions, and δ 18 O values was observed in different water samples, especially in river water samples. (2) The annual average contributions of shallow groundwater, precipitation, and glacier/snow meltwater to regional runoff in the AICA were 49.6 %±9.3 %, 32.6 %±11.8 %, and 17.8 %±7.4 %, respectively. (3) Spatial heterogeneity in the inland river runoff composition pattern was observed in the AICA, particularly in spring. (4) The Shiyang River was found to have a potential drinking water safety risk, while oasis agriculture in the Aksu River basin should be limited. Regional environmental fluctuations posed new challenges for the simulation and estimation of regional inland river runoff. The results of this study provide a substantial background for planning the sustainable utilization of regional water resources. Characteristics of annual runoff components in inland rivers of the study area. • Heterogeneity of hydrochemical and δ 18 O/δ 2 H of multiple water sources was explored for the study region. • Spatial heterogeneity in the inland river runoff composition pattern was observed in the AICA, particularly in spring. • The Aksu River and Shiyang River basins are more sensitive to changes in environmental elements.