Mountain regions are highly climate-sensitive, yet long-term observational evidence of elevation and seasonal climate dynamics in Central Asia remains limited. This study examines spatiotemporal trends in temperature (Tmean, Tmax, Tmin, and diurnal temperature range [DTR]) and precipitation across Kazakhstan’s transmountain regions using 74 meteorological stations (1981–2023). Data were analyzed using the Mann–Kendall test and Sen’s slope estimator, stratified across six elevation zones from lowlands (1500 m). Results reveal a robust, spatially coherent warming signal across all zones. Annual Tmean increased at a median rate of ~0.30 °C decade⁻¹, peaking at 0.36 °C decade⁻¹ above 1500 m, corresponding to an absolute increase exceeding 1.5 °C. Warming exhibited strong seasonal and diurnal asymmetries. Spring warmed most rapidly, with Tmean increasing >0.60 °C decade⁻¹ (approaching 3 °C total). Winter warming was driven by Tmin increases (up to 0.44 °C decade⁻¹), causing widespread DTR contraction, whereas summer warming was driven by Tmax increases, expanding DTR at higher elevations. Tmin showed the strongest elevation amplification overall. In stark contrast, precipitation trends were weak, spatially heterogeneous, and largely non-significant. Annual changes ranged from −6.63 to +14.35 mm decade⁻¹, with seasonal tendencies indicating modest, non-significant winter/spring wetting and summer drying. Ultimately, the results demonstrate a profound decoupling between strong, elevation-dependent warming and weak precipitation changes. The acute amplification of temperature, particularly during spring and summer at high elevations, has severe implications for snowmelt timing, glacier mass balance, evapotranspiration demand, and long-term water security in Kazakhstan.

Oases in arid regions consist of river–lake–groundwater systems characterized by complex hydrological cycles and fragile ecosystems. Sustainable water resource management, aimed at multi-source ecological restoration, is crucial for oasis ecological protection and represents a current research challenge. This study focuses on the Bohu irrigation area, using ecological water levels, the MIKE-SHE hydrological model, and the water balance equation to propose a multi-objective groundwater and surface water regulation scheme that meets both the ecological safety requirements of the irrigation area and the ecological water demands of the Small Lake. Key findings include the following: (1) The regional ecological water level ranges from 1.69 m to 4 m, with about 74% of the area exceeding this range, threatening local ecology. (2) The proposed regulation method adjusts 91.25% of areas exceeding the ecological water level to within the acceptable range. (3) Under various planting scenarios, the minimum water distribution from the west branch of the BLSM water diversion hub should be 824.632 ${\times 10}^6 {\mathrm{m}}^3/\mathrm{a}$ to meet Small Lake ecological demands. When this volume exceeds 831.902 ${\times 10}^6{\mathrm{m}}^3/\mathrm{a}$, both groundwater regulation and Small Lake ecological demands are satisfied. This paper quantifies the water cycle mechanisms in complex hydrological interaction areas, providing specific solutions to regional ecological problems, which holds significant practical relevance.