Variations in runoff and sediment discharge are important characteristic variables for revealing the coupled effects of climate change (including both the natural variability of climate and anthropogenic climate change) and human activities (including soil and water conservation measures, land use changes, and hydraulic engineering construction). Based on the meteorological data from 19 meteorological stations and the hydrological data from the watershed control station of Hongqi Station, the temporal and spatial evolution of runoff and sediment discharge and the water–sand relationship were analyzed, and the response mechanisms of runoff and sediment discharge changes were clarified using Mikhail Budyko’s theory and other qualitative and quantitative methods. The results determined that: (1) The runoff and sediment discharge showed significant downward trends, with linear change rates of −0.28 × 10⁸ m³/a and −46.10 × 10⁴ t/a, respectively. The change points of the runoff and sediment discharge occurred in 1987 and 1996, respectively. (2) The spatial distribution of water and sediment was different, and the upper and middle reaches produced water, while the downstream produced sediment. (3) Comparing potential evapotranspiration and rainfall based on Budyko theory and the regression relationship, runoff is more closely related to rainfall, and runoff changes are more affected by it. The change in sediment discharge is most closely related to sediment concentration, followed by rainfall and potential evaporation. (4) The contribution rates of runoff and sediment discharge changes influenced by climate change were 24% and 3%, respectively, and the contribution rates by human activities were 76% and 97%, respectively. Human activities, including soil and water conservation measures, land use changes, and hydraulic engineering construction were the main influencing factors, and the impacts of human activities increased from 1960 to 2019. The research results are of great significance for erosion control and ecological restoration in the Tao River Basin under the conditions of the changing environment.

Considering the possibility of increasing water supply in China in the short term and the long-term threat posed by shrinking glaciers, this paper studied the spatiotemporal evolution of runoff in typical arid areas and the influence of hydrometeorological elements on runoff, aiming to clarify the hydrological cycle law and provide a basis for adjusting water resource management strategies to cope with future uncertain changes. Based on hydrological data from 1956 to 2020, the spatial and temporal variation in runoff were discussed by means of wavelet analysis, MK test, RS analysis, and spatial interpolation. The influencing factors of runoff evolution in the Shule River Basin were determined. The results showed that the runoff in the Shule River Basin showed an increasing trend in the past 60 years. Five hydrological stations (Changmabao Station, Panjiazhuang Station, Shuangtabao Reservoir, Dangchengwan Reservoir, and Danghe Reservoir) were selected as the research objects. Among them, the runoff of Changmabao Station increased the most, which was 1.202 × 10⁸ m³/10 a. Future projections suggest a continued rise in runoff, particularly at Shuangtabao Reservoir. The runoff exhibited positive persistence and varying degrees of mutation, with most mutations occurring in the early 21st century. The runoff in the basin has a periodicity of multiple time scales (there are 2–3 main cycles), and the main cycle of annual runoff is concentrated in 58 years. This comprehensive analysis provides valuable insights for the sustainable management of water resources in inland river basins amidst changing environmental conditions. The spatial variation in runoff in summer and autumn and the whole year showed a significant southeast to northwest decreasing pattern. During the study period, accelerated glacier melting caused by rising temperatures had the most significant impact on runoff change (p < 0.01), and the upstream of the study area also complied with this rule (temperature contribution rate [25.96%] > precipitation contribution rate [23.91%]). The contribution of temperature and precipitation changes caused by human activities in the middle stream to runoff was relatively large, which showed that the contribution rate of temperature in Guazhou Station to runoff was 34.23% and the contribution rate of precipitation in Dangchengwan to runoff was 60.27%. The research results provide a scientific basis for the rational and efficient utilization of water resources in the arid area of Northwest China.

Water ecological security is intricately connected to regional economic development and human survival, exerting a profound influence on regional sustainability. Water ecological security in the study area is a matter of urgency. In this study, the socio-economic, ecological, and water resource data of five cities in the west of the river from 2006 to 2021 are used to construct a dynamic model of the regional water ecological security system and simulate the trend of the regional water ecological security from 2022 to 2035, and the results indicate the following: (1) From 2006 to 2021, Hexi Corridor’s economy exhibited a significant upward trend, while its total population experienced a marked decline. Indicators for the ecological environment system showed notable improvement, whereas those for the water resource system demonstrated a significant downward trend. (2) Spatially, the mean values of system indices in the southeast and northwest regions were higher than those in the central region. (3) Between 2022 and 2035, projections reveal that the total GDP, industrial added value, average sewage discharge, urban green space, and water consumption for ecological purposes will all trend upward. Concurrently, the total population, total water supply, and total water demand are expected to exhibit a continuous decline. (4) The comparative comprehensive scores of the scenario models are as follows: EPS (2.18) > RSS (1.57) > CDS (1.15) > EDS (1.08). This analysis provides valuable insights into the dynamics of water ecological security in the Hexi Corridor and offers critical guidance for sustainable regional development planning.

To explore the mechanisms driving variation in ET₀ (reference evapotranspiration) in an arid inland region of Northwest China, daily meteorological data from 1960 to 2019 from 19 meteorological stations in the Taohe River basin and its surrounding areas were used to analyze the temporal and spatial distributions of ET₀ and meteorological variables. Various qualitative and quantitative analysis methods were used to reveal the correlation between ET₀ and meteorological variables. The degree of sensitivity of ET₀ variations to meteorological variables and the contribution from each meteorological variable were clarified, and the mechanisms driving variation in ET₀ were fully revealed. These are the results: (1) ET₀ in the Taohe River basin presented a significant upward trend with a linear change rate of 0.93 mm/a, and a sudden change occurred in 1994. The spatial variation in ET₀ ranged from 779.8 to 927.6 mm/a, with low values in the upper and middle reaches and high values in the lower reaches. The ET₀ at 14 stations (73.68% of the total) was significantly increased (p < 0.05), and that at 5 stations (26.32% of the total) was not significantly increased (p > 0.05). (2) RH, R_n, and u₂ did not change significantly, while T_max and T_min showed a significant upward trend. (3) R_n is a meteorological variable closely related to variations in ET₀, and is the most sensitive variable for variations in ET₀, followed by T_max and u₂. (4) T_max is the meteorological variable that contributes most to the variation in ET₀ (30.98%), followed by T_min (29.11%), u₂ (6.57%), R_n (2.22%), and RH (0.05%). The research results provide a scientific basis for the rational and efficient utilization of water resources and the maintenance of ecosystem health.

Water Resource Carrying Capacity (WRCC) is a crucial measure for assessing the balance between regional water availability, socioeconomic development, and ecological needs, especially in arid and semi-arid regions. This study evaluates the spatiotemporal evolution of WRCC across 14 prefecture-level units in Gansu Province, China, from 2000 to 2023. A multi-dimensional evaluation system comprising 29 indicators across water resources, ecological environment, economy, society, and coordination subsystems was established. The Entropy Weight Method was applied to determine indicator weights and calculate a comprehensive index (CI) to quantify carrying pressure. A Random Forest model identified dominant influencing factors, and an autoregressive integrated moving average model projected trends from 2024 to 2028. The results show the provincial mean CI increased from 0.49 to 0.91, indicating intensifying pressure and a shift toward mild overload. Spatially, pressure exhibits a stable west–east gradient, with the highest levels persistently in western prefectures like Jiuquan, Jinchang, and Baiyin. In contrast, Gannan and Longnan in the south maintain lower pressure but show high interannual variability, indicating ecological sensitivity. The Random Forest model demonstrated strong performance, with training R² values exceeding 0.88 across all regions and mean absolute error mostly below 0.10. Projections suggest continued high pressure from 2024 to 2028 in the west, while central and southern regions show stable or slightly decreasing trends. These findings provide a quantitative basis for establishing differentiated, zoned water resource management and sustainable demand-side regulation strategies in water-limited regions.