As an important indicator for assessing regional water resources, the study of the spatiotemporal evolution and driving factors of water resources carrying capacity (WRCC) is essential for achieving sustainable water resource utilization. This study focuses on Yulin City, a typical arid region located on the Loess Plateau in northwestern China. By constructing an evaluation index system for regional WRCC and combining an improved fuzzy comprehensive evaluation model with the TOPSIS evaluation model, a comprehensive WRCC evaluation model is established. Additionally, Geodetector is used to explore the main driving factors behind the evolution of regional WRCC. This multidimensional analytical framework aims to deeply analyze the dynamic evolution trends of WRCC and the driving mechanisms of different factors in its spatiotemporal changes. The results indicate that (1) from 2011 to 2020, the overall WRCC of Yulin City showed a trend of positive improvement, with Shenmu, Yuyang, and Fugu areas performing the best, and by 2020, more than half of the counties had achieved Grade 3 or above; (2) the spatial variability of WRCC in Yulin City was more significant than its temporal changes; and (3) in terms of driving mechanisms, the northern six counties gradually shifted from traditional economic-driven factors to ecological and environmental drivers, whereas the southern six counties remained constrained by economic factors. Overall, water resource factors remain the primary driving force for the socio-economic development and environmental sustainability of the entire Yulin City. The study provides valuable information for water resource allocation and differentiated management in arid regions.

Inter-basin water diversion projects have emerged as a critical solution to address water scarcity crises stemming from the uneven spatial distribution of water resources. The economic feasibility of these projects is significantly influenced by multiple factors, including water source composition, target beneficiaries, and the specific characteristics of diversion routes and distances. This research developed a novel multi-objective optimization framework utilizing a simulation-based optimization methodology designed to formulate efficient joint operational strategies that maximize water supply reliability while reducing operational expenditures. The practicality of this framework is validated through its implementation in the Yangtze to Huaihe River Water Diversion Project (YHWDP) in China. The results revealed that the proposed joint operation rules achieve substantial improvements in both water supply efficiency and cost-effectiveness. Specifically, the model demonstrated the capability to maintain a 95.5% water supply rate while reducing the water pumping volume to only 1.84 × 10⁹ m³. Furthermore, comparative analyses with conventional operation rules showed that the joint operation strategy effectively utilized the runoff regulation capacity of lakes while significantly mitigating water level fluctuations. During the water diversion period, the average variance of the time series of water volume in three lakes decreased by 54.5%, thereby contributing to the preservation of ecological stability for lake flora and fauna. The findings of this research not only provided practical insights for optimizing the operational performance of the YHWDP but also established a valuable framework for developing joint operation strategies in similar long-distance water diversion projects between basins.

The water source protection areas of the Yangtze-to-Huaihe Water Diversion Project (YHWDP) in Anhui Province serve as crucial ecological barriers to water quality protection. Quantifying their eco-environmental quality (EEQ) dynamics and driving mechanisms is critical for sustainable management. This paper calculated the Remote Sensing Ecological Index (RSEI) for the study area using Landsat satellite data (2015–2024). Temporal and spatial variation characteristics were analyzed using the Theil–Sen estimator, Mann–Kendall test, and coefficient of variation. Future trends were predicted using the Hurst exponent. Finally, the Geodetector model was applied to assess the impact of driving factors. EEQ exhibited a declining trend (p < 0.05), with significant intra-regional heterogeneity. Mean RSEI values ranked as follows: (1) Yangtze River–Huaihe River Connection < Yangtze River Water Northward Conveyance < Yangtze River–Chaohu Lake Water Diversion. (2) From 2015 to 2024, eco-environmental quality improved significantly, showing a spatial pattern of “south > north, east > west.” (3) Overall EEQ changes were characterized by slight to moderate fluctuations. Stability rankings: Yangtze River–Huaihe River Connection > Yangtze River–Chaohu Lake Water Diversion > Yangtze River Water Northward Conveyance. (4) Geodetector analysis identified precipitation, impervious area, and vegetation coverage as the primary factors influencing EEQ in the YHWDP’s water source protection areas. This study reveals ecological changes in the YHWDP region and validates the effectiveness of the comprehensive evaluation method. The findings provide actionable insights for ecological protection in large-scale water diversion projects.

The rising levels of Co(II) in aquatic environments present considerable risks, thereby necessitating the development of effective remediation strategies. This study introduces an innovative pre-hydration method for synthesizing carbonated calcined clay dolomite (CCCD) to efficiently remove Co(II) from contaminated water. This pre-hydration treatment successfully reduced the complete carbonation temperature of the material from 500 °C to 400 °C, significantly enhancing energy efficiency. The Co(II) removal performance was systematically investigated by varying key parameters such as contact time, initial Co(II) concentration, pH, and solid/liquid ratio. Optimal removal was achieved at 318 K with pH of 4 and a solid/liquid ratio of 0.5 g·L⁻¹. Continuous flow column experiments confirmed the excellent long-term stability of CCCD, maintaining a consistent Co(II) removal efficiency of 99.0% and a stable effluent pH of 8.5 over one month. Isotherm and kinetic models were used to empirically describe concentration-dependent and time-dependent uptake behavior. The equilibrium data were best described by the Langmuir model, while kinetics followed a pseudo-second-order model. An apparent maximum removal capacity of 621.1 mg g⁻¹ was obtained from Langmuir fitting of equilibrium uptake data. Mechanistic insights from Visual MINTEQ calculations and solid phase characterizations (XRD, XPS, and TEM) indicate that Co(II) removal is dominated by mineral water interface precipitation. The gradual hydration of periclase (MgO) forms Mg(OH)₂, which creates localized alkaline microenvironments at particle surfaces and drives Co(OH)₂ formation. Carbonate availability further favors CoCO₃ formation and retention on CCCD. Importantly, this localized precipitation pathway maintains a stable, mildly alkaline effluent pH (around 8.5), reducing downstream pH adjustment demand and improving operational compatibility. Overall, CCCD combines high Co(II) immobilization efficiency, strong long-term stability, and an energy-efficient preparation route, supporting its potential for scalable remediation of Co(II) contaminated water.

Understanding the correlation between water resources quantity and the urbanization process is crucial for achieving coordinated development of a socio-economy and ecological security in river basin cities. Taking the water resources quantity (including total water resources quantity, water supply quantity, and water consumption) and urbanization process indicators (including GDP, permanent resident population, agricultural irrigation quantity, and waterway transportation quantity) of the study area from 2011 to 2024 as the objects, this paper adopts a Pearson correlation analysis and linear regression methods to analyze the correlation characteristics between them. The results revealed that total water resources quantity was significantly positively correlated with GDP (r = 0.578 *; p < 0.05), permanent resident population (r = 0.708 **; p < 0.01) and waterway transportation quantity (r = 0.535 *; p < 0.05) but had no significant correlation with agricultural irrigation quantity (r = −0.396). Water supply quantity and water consumption presented significant negative correlations with GDP (r = −0.711 *; r = −0.601 *) and waterway transportation quantity (r = −0.797 **; r = −0.736 **), highly significant positive correlations with agricultural irrigation quantity (r = 0.854 **; r = 0.879 **), and no significant correlation with permanent resident population (r = −333; r = −383). This study uncovers the differentiated responses of water resource indicators to socio-economic activities amid urbanization, which not only reflects the evolution of the regional water consumption structure but also verifies the effectiveness of water conservation efforts. It provides a scientific basis for the sustainable utilization and optimized management of water resources in the development process of Bengbu city.

The effective utilization of recycled concrete powder remains a key challenge for sustainable construction. In this study, carbonated recycled concrete powder (CRCP) was applied to replace cement at levels of 4–16% in Portland cement–fly ash (OPC-FA) systems, and its effects on fresh properties, hydration behavior, shrinkage, pore structure, and mechanical performance were systematically investigated. The incorporation of CRCP reduced flowability and accelerated setting, while slightly advancing and enhancing the main hydration peak at 4–8% replacement, accompanied by higher CH at early ages and increased C–S–H formation at later stages. More significantly, the addition of CRCP substantially decreased both autogenous and drying shrinkage, achieving reductions in the ranges of 6.0–21.4% and 3.2–24.1%, respectively. This improvement is primarily attributed to the elevated internal relative humidity and the lowered capillary pressure within the system. In addition, the mechanical properties exhibited a clear optimum with the addition of 8% CRCP, where the 28 d compressive strength and flexural strengths increased by 16.3% and 4.0%, respectively. Further analysis indicates that this improvement is associated with a higher fraction of high-modulus regions and an increase in average elastic modulus from 23.89 GPa to 27.42 GPa, reflecting a denser microstructure. These results demonstrate that CRCP can effectively regulate hydration and microstructure, providing a feasible approach for improving dimensional stability and mechanical performance while enabling the value-added utilization of recycled concrete powder.