Impact of Climatic Conditions on Extremely Low Water Discharges in the Steppe Basins of Kazakhstan

This study investigates the spatiotemporal variability of minimum river discharge in Northern Kazakhstan and its sensitivity to climatic factors under continental and semi-arid conditions. Long-term meteorological and hydrological data from key regional rivers, including Tobyl, Toguzak, Torgay, Karatorgay, and Ayat, were analyzed to detect structural shifts, trends, and stationarity. Structural changes were identified using Pettitt’s test and supported by difference-integral and cumulative-integral curves, while linear trend analysis with 10-year moving averages highlighted long-term tendencies. Correlation analysis assessed the influence of temperature and precipitation, distinguishing low- and high-flow years. Stationarity and homogeneity were evaluated with ADF, KPSS, and complementary parametric and non-parametric tests to ensure robust statistical interpretation. Results reveal significant structural shifts during 1980–1990, with rising winter air temperatures and marked heterogeneity of minimum discharge, especially in cold seasons. Winter flows are predominantly controlled by temperature and groundwater recharge, while summer flows are strongly linked to precipitation dynamics and evapotranspiration processes. Differences between low- and high-flow years confirm the dynamic non-stationarity of the system. These findings enhance understanding of regional hydro-climatic interactions and provide a scientific basis for adaptive water resource management, reservoir regulation, and long-term strategies of climate change adaptation in the steppe and semi-arid regions of Central Asia.