Search Results (107)

This study aims to improve the accuracy and interpretability of deep groundwater level forecasting in Cangzhou, a typical overexploitation area in the North China Plain. To address the limitations of traditional models and existing machine learning approaches, we develop a Stacking ensemble learning framework that integrates meteorological, spatial, and anthropogenic variables, including lagged groundwater levels to reflect aquifer memory. The model combines six heterogeneous base learners with a meta-model to enhance prediction robustness. Performance evaluation shows that the ensemble model consistently outperforms individual models in accuracy, generalization, and spatial adaptability. Scenario-based simulations are further conducted to assess the effects of the South-to-North Water Diversion Project. Results indicate that the diversion project significantly mitigates groundwater depletion, with the most overexploited zones showing water level recovery of up to 17 m compared to the no-diversion scenario. Feature importance analysis confirms that lagged water levels and pumping volumes are dominant predictors, aligning with groundwater system dynamics. These findings demonstrate the effectiveness of ensemble learning in modeling complex groundwater behavior and provide a practical tool for water resource regulation. The proposed framework is adaptable to other groundwater-stressed regions and supports dynamic policy design for sustainable groundwater management. Full article

To investigate the spatiotemporal distribution characteristics of nitrogen and phosphorus in the water and sediment of the Danjiangkou Reservoir, the source of the Middle Route of China’s South-to-North Water Diversion Project, we designed a year-long monitoring program. The water and sediment samples were collected from 13 sampling points in the upstream and downstream areas over the year. The results revealed significant spatial heterogeneity in N and P concentrations, with higher levels of total nitrogen, nitrate nitrogen, and nitrite nitrogen in the upstream area compared to the downstream area (p < 0.01). Total phosphorus was also significantly higher in the upstream area (p < 0.05). Seasonal variations were observed, with TN and TP levels peaking in February and August, respectively. The TN:TP ratio indicated a severe P-limited state in most periods, transitioning to a co-limited state of N and P during summer. Sediment analysis showed that TN and TP concentrations were higher in the upstream area, with no significant differences between upstream and downstream on an annual basis, exhibiting strong stoichiometric internal stability. However, seasonal differences were noted, particularly in February and November. This study highlights the complex interactions between water and sediment, emphasizing the role of sediment resuspension, water flow, and seasonal changes in nutrient dynamics. These findings provide a scientific basis for the management and protection of water quality in the Danjiangkou Reservoir, ensuring its role as a critical water source for the South-to-North Water Diversion Project. Full article

Complex feedback mechanisms and interdependencies exist among the water–energy–food–ecosystems (WEFE) nexus. In water-scarce regions, fluctuations in the supply or demand of any single subsystem can destabilize the others, with water shortages intensifying conflicts among food production, energy consumption, and ecological sustainability. Balancing the synergies and trade-offs within the WEFE system is therefore essential for achieving sustainable development. This study adopts the natural–social water cycle as the core process and develops a coupled simulation model of the WEFE (CSM-WEFE) system, integrating food production, ecological water replenishment, and energy consumption associated with water supply and use. Based on three performance indices—reliability, coupling coordination degree, and equilibrium—a coordinated sustainable development index (CSD) is constructed to quantify the performance of WEFE system under different scenarios. An integrated evaluation framework combining the CSM-WEFE and the CSD index is then proposed to assess the sustainability of WEFE systems. The framework is applied to the Beijing–Tianjin–Hebei (BTH) region, a representative water-scarce area in China. Results reveal that the current balance between water supply and socio-economic demand in the BTH region relies heavily on excessive groundwater extraction and the appropriation of ecological water resources. Pursuing food security goals further exacerbates groundwater overexploitation and ecological degradation, thereby undermining system coordination. In contrast, limiting groundwater use improves ecological conditions but increases regional water scarcity and reduces food self-sufficiency. Even with the full operation of the South-to-North Water Diversion Project (Middle Route), the region still experiences a 16.4% water shortage. By integrating the CSM-WEFE model with the CSD evaluation approach, the proposed framework not only provides a robust tool for assessing WEFE system sustainability but also offers practical guidance for alleviating water shortages, enhancing food security, and improving ecological health in water-scarce regions. Full article

The hydrodynamics characteristics of artificial water diversion canals with long-distance and inter-basin multi-stage sluice gate regulations are prone to sudden increases and decreases, and sluice gate discharge differs from that of natural rivers. Research on the change characteristics of hydrological elements in artificial canals under the control of sluice gates is lacking, as are scientifically accurate calculations of sluice gate discharge. Therefore, addressing these gaps in long-distance artificial water transfer is of great importance. In this study, real-time operation data of 61 sluice gates, pertaining to the period from May 2019 to July 2021, including data on water levels, flow discharge, velocity, and sluice gate openings in the main canal of the Middle Route of the South-to-North Water Diversion Project of China, were analyzed. The discharge coefficient of each sluice gate was calculated by the dimensional analysis method, and the unit-width discharge was modeled as a function of gate opening ($e$), gravity acceleration ($g$), and energy difference ($H$). Through logarithmic transformation of the Buckingham Pi theorem-derived equation, a linear regression model was used. Data within the relative opening orifice flow regime were selected for fitting, yielding the discharge coefficients and stage–discharge relationships. The results demonstrate that during the study period, the water level, discharge, and velocity of the main canal showed an increasing trend year by year. The dimensional analysis results indicate that the stage–discharge response relationship followed a power function ($Q\propto {(\frac{H}{e})}^{constant}$) and that there was a good linear relationship between $l{g}^{(\frac{H}{e})}$ and $l{g}^{(\frac{K}{e})}$ (R² > 0.95, $K={(q^2/g)}^{1/3}$). By integrating geometric, operational, and hydraulic parameters, the proposed method provides a practical tool and a scientific reference for analyzing sluice gates’ regulation and hydrological response characteristics, optimizing water allocation, enhancing ecological management, and improving operational safety in long-distance inter-basin water diversion projects. Full article

With the increasingly severe problem of water shortage and the increasing contradiction between supply and demand, the optimal allocation of water resources has become an essential method for alleviating the water crisis. In this context, natural-element-inspired optimization algorithms have been extensively used to solve water resource optimization problems. The hunting search (HUS) algorithm has a slow convergence speed, and low accuracy, which makes it easy to fall into local optima when solving multi-objective problems, and it is also not easy to apply directly to multi-objective optimization. It is improved by introducing a fast, non-dominated sorting, congestion comparison operator, and elite retention strategy. The improved algorithm was evaluated against popular algorithms using the ZTD series of objective functions, and the results indicate that the improved algorithm performs better in terms of convergence and diversity of solution sets. The improved algorithm is then applied to solve the optimal allocation model for water resources in the receiving area of the South-to-North Water Diversion Project in Hebei Province, which is based on the objective of social and economic benefits. Based on the obtained Pareto optimal frontier, the scheme with a special preference for the minimum shortage of water resources is selected as the ultimate decision-making scheme. The optimization results show that in 2030, the total water demand of water users in the receiving area is 4661.82 × 10⁶ m³, the total water allocation is 4082.88 × 10⁶ m³, and the water deficit is 578.94 × 10⁶ m³. The improved hunting search algorithm offers a new solution method for the multi-objective water resource optimization allocation problem. Full article

The riverine fish species are highly vulnerable and responsive to large-scale water diversion projects. These adverse impacts are more pronounced in the plateau river ecosystems, which may change the environmental conditions of fish habitats and community structure. We investigated the effects of various environmental factors on fish diversity in seven rivers of the Western Sichuan Plateau, which is the planned area of China’s South-to-North Water Diversion Project. Twenty-two fish species, including eight exotic species, were collected during September 2023 (Autumn) and May 2024 (Spring). The fish communities exhibited no significant difference between seasons but had prominent variations among different rivers. The heterogeneity of fish communities was significantly and positively correlated with the geographical distance between the sampling sites (based on a projected coordinate system). Furthermore, the canonical correspondence analysis (CCA) illustrated that altitude contributed more to the distribution of fish species than other physicochemical factors, such as channel width, conductivity, and water temperature. Rivers at low altitudes are likely to be vulnerable to invasion of exotic fish. Our results demonstrated that the dispersal limitation by geographical distance and altitudinal gradient were the primary regulatory factors on the spatial differentiation of fish communities in the rivers of the study area, which reflected a high dependence of fish species on local habitats. As the water diversion project is implemented, more attention is expected to be paid to protecting fish habitats and regime shifts in fish communities. Additionally, the risk assessment of biological invasion under inter-basin water transfers and human activities should be carried out as soon as possible. Full article

This study presented a comprehensive analysis of the microbial ecology in water diversion rivers (WDRs) in the source area of the East Route of the South-to-North Water Diversion Project (ER-SNWDP) in China across various water periods. Proteobacteria, Chloroflexi, Acidobacteriota, and Bacteroidota were identified as the dominant microbial phyla in river sediment. During the wet period, microbial communities exhibited the highest richness, biodiversity, and the most intense antagonistic relationships compared to those in the dry and normal water periods. Generally, the microbial network predominantly existed in symbiotic models characterized by mutual benefit and symbiosis throughout all periods. During the dry period, the microbial co-occurrence network was found to be the most complex, with microbial OTUs showing the closest interconnections. The dominant mechanisms governing community diversity, succession, and biogeography were spatial turnover of species and stochastic processes. A more pronounced impact of stochastic processes on microbial community assemblages was observed during normal or wet periods than the dry period. Functional prediction of metabolic pathways indicated that the main ecological functions of microbial communities encompassed carbohydrate metabolism, amino acid metabolism, energy metabolism, etc. This study could provide essential scientific data for ecological regulation, ecological protection, and water resources management in WDRs. Full article

The route of the South-to-North Water Diversion channel strides across part of the coal mine goaf in Yuzhou County, Henan Province, China, and long-term deformation due to coal seam recovery poses a threat to the safe operation of the main canal. Therefore, the study of the deformation mechanisms induced by coal seam recovery is of great significance to the canal’s safe operation, as well as to deformation monitoring and to the development of early warnings. The geologic model was established based on the geological engineering conditions of the Yuzhou Gongmao mining area, spanning the main canal of the South-to-North Water Diversion Project; then, the physical model test was carried out according to similar theories. The deformation characteristics of the rock overlay and the channel above the goaf were analyzed, and failure criteria for overburdened rock and the channel were proposed. The results showed that horizontal fissures were gradually observed in the overlying rock as the coal mining progressed, extending and widening. When the goaf was excavated to 76 cm, the overlying rock body suddenly collapsed as a whole, and the channel collapsed and was destroyed. During the formation of the goaf, there was a critical span ratio (R): When the height-to-span ratio was greater than 0.039, the collapse of overlying rock occurred only within a certain range above the goaf. When the height-to-span ratio was less than 0.039, the overlying rock body collapsed in a wide area, and the soil on both sides of the channel collapsed to the center of the channel, presenting a “V” glyph collapse. The sediment in the center of the channel measured 22 mm, and there were multiple tensile cracks on both sides of the embankment, with a width of 5–10 mm. The vertical deformation of the channel went through three stages, namely, the initial deformation stage, the deceleration deformation stage, and the stability stage. This study can provide scientific guidance for early warnings of channel deformation and safe operation across the goaf. Full article

Due to the increasing impact of human activities on the environment, habitat loss, fragmentation, and degradation pose significant threats to bird diversity worldwide. Baiyangdian, the largest freshwater lake wetland in North China, is an important habitat for birds. The degradation of water quality caused by decaying reed rhizomes has prompted governmental initiatives for ecological restoration in Baiyangdian. However, it has also led to the significant destruction of reed habitats within the wetlands consequently. Bird species that rely on these reed habitats, especially the reed parrotbill, face a significant threat, necessitating the establishment of species reserves to mitigate the loss of bird diversity. Our research aims to identify the potential suitable habitats for the reed parrotbill in Baiyangdian and establish priority conservation areas. Using the environmental factors determined with Google Earth Engine (GEE), ultimately we designated the following areas as priority conservation zones: the Fuhe Wetland (FHW), the reed area south of Beihezhuang (BHV), both sides of the Baiyangdian Bridge (BYDB), the western shoreline of Shaochedian (SCD), Yannandi Park (YNDP), east of Guangdianzhangzhuang Village (GDZZV), east of Dongtianzhuang (DTV), north of Xilizhuang (XLV), south of Caiputai Village (CPTV), north of Gaolou Village (GLV), and the Xiaoyihe Wetland (XYW). Our findings provide a scientific reference for ecological restoration projects in the Baiyangdian region and offer supporting data for the conservation management of the reed parrotbill. Full article

Taking Yunyu New Village in Nanyang City, a typical newly built resettlement area of the South-to-North Water Diversion Project of China, as an example, this paper tries to construct a health environment evaluation index system for the resettlement area and determines the priority and content of residential environment renovation in the resettlement area through residents’ health satisfaction evaluation and IPA analysis. The results revealed that six factors, namely, winter insulation, summer heat insulation, quality of domestic drinking water, indoor natural light environment, humanized design, and architectural plane function design, need to be renovated first. For the indoor environment, which is the focus of renovation, the light and heat environments were evaluated via field measurements and simulation experiments. The results show that the indoor comfort, daylighting, and energy savings of the surveyed buildings all fail to meet Chinese building design standards. Corresponding optimization strategies for indoor ventilation, thermal insulation performance of the envelope structure, and window wall ratio are proposed and verified via relevant software simulations and immigrants’ wishes. For the outdoor environment, we investigate the living habits and renovation needs of immigrants from the aspects of public space and courtyard space in the resettlement area and propose corresponding optimization strategies. The results of this research can help enhance the sense of gain and happiness of immigrants in the resettlement and provide a reference for improving the living environment of the same type of immigrant resettlement area. Full article

Ecological governance projects have great potential benefits, but there is a lack of quantitative evaluation of their impacts in terms of enhancing regional ecological carrying capacity under climate change. To quantitatively evaluate the impact of ecological governance projects on regional ecological carrying capacity, a quantitative evaluation model was developed by coupling the classical ecological footprint and ecological service value theory. This model was validated using the water source treatment project (hereinafter referred to as the “DZ” project) of the Middle Route of China’s South to North Water Diversion Project, which is the world’s largest water diversion project, as an example. The results showed the following: (1) During the implementation of the “DZ” project, the per capita ecological carrying capacity of the reservoir area experienced a wave-like growth trend, with an increase of 0.103615 hm² and a yield increase rate of 20.00%. The “DZ” project has outstanding ecological benefits, valued at approximately USD 125.272266 million. (2) The “DZ” project has contributed to the improvement of the ecological carrying capacity in the Henan area of the Danjiang Reservoir by about 10.14%, demonstrating that such projects have a considerable impact on efforts to improve regional ecological carrying capacity under climate change. Full article

The South-to-North Water Diversion Project in China is the world’s largest water transfer project, aiming to address water shortages in northern China by channeling water from the water-rich southern regions. Water resources in Tianjin have long been in severe deficit, with excessive groundwater extraction causing significant surface subsidence, negatively impacting urban infrastructure and economic development. As a result, Tianjin has become a key beneficiary of this water diversion project. To investigate the current situation of surface subsidence, we obtained the vertical displacement time series from 21 GNSS stations across Tianjin from 2011 to 2021 and analyzed overall subsidence changes and rehabilitation status. Results indicate that no clear surface subsidence was observed in the northern regions of Tianjin due to groundwater extraction mainly in unconfined aquifers. The southwestern region experienced the most significant surface subsidence due to overexploitation of deep groundwater, with peak cumulative subsidence exceeding 600 mm during the study period. The central, eastern, and southeastern coastal regions also faced severe surface subsidence with cumulative amounts ranging from 100 mm to 400 mm. The alleviation of subsidence predominantly benefits from continuous water supply from the South to North Water Diversion Project, which resulted in most stations significantly slowing down or even stabilizing their settlement rates after 2018. Therefore, the South-to-North Water Diversion Project plays a crucial role in addressing the persistent water resource shortage and mitigating long-term surface subsidence in Tianjin by ensuring a continuous water supply and significantly reducing the need for groundwater extraction. Our findings indicate positive measures, such as water diversion projects and water management policies, can serve as valuable references for other regions around the world facing similar water scarcity and groundwater overexploitation. Full article

Under the background of global change, the lake water environment is facing a huge threat from eutrophication. The rapid increase in curly-leaf pondweed (Potamogeton crispus L.) in recent years has seriously threatened the ecological balance and the water diversion safety of the eastern route of China’s South-to-North Water Diversion Project. The monitoring and control of curly-leaf pondweed is imperative in shallow lakes of northern China. Unmanned Aerial Vehicles (UAVs) have great potential for monitoring aquatic vegetation. However, merely using satellite remote sensing to detect submerged vegetation is not sufficient, and the monitoring of UAVs on aquatic vegetation is rarely systematically evaluated. In this study, taking Nansi Lake as a case, we employed Red–Green–Blue (RGB) UAV and satellite datasets to evaluate the monitoring of RGB Vegetation Indices (VIs) in pondweed and mapped the dynamic patterns of the pondweed Fractional Vegetation Coverage (FVC) in Nansi Lake. The pondweed FVC values were extracted using the RGB VIs and the machine learning method. The extraction of the UAV RGB images was evaluated by correlations, accuracy assessments and separability. The correlation between VIs and FVC was used to invert the pondweed FVC in Nansi Lake. The RGB VIs were also calculated using Gaofen-2 (GF-2) and were compared with UAV and Sentinel-2 data. Our results showed the following: (1) The RGB UAV could effectively monitor the FVC of pondweed, especially when using Support Vector Machine that (SVM) has a high ability to recognize pondweed in UAV RGB images. Two RGB VIs, RCC and RGRI, appeared best suited for monitoring aquatic plants. The correlations between four RGB VIs based on GF-2, i.e., GCC, BRI, VDVI, and RGBVI and FVC_SVM calculated by the UAV (p < 0.01) were better than those obtained with other RGB VIs. Thus, the RGB VIs of GF-2 were not as effective as those of the UAV in pondweed monitoring. (2) The binomial estimation model constructed by the Normalized Difference Water Index (NDWI) of Sentinel-2 showed a high accuracy (R² = 0.7505, RMSE = 0.169) for pondweed FVC and can be used for mapping the FVC of pondweed in Nansi Lake. (3) Combined with the Sentinel-2 time-series data, we mapped the dynamic patterns of pondweed FVC in Nansi Lake. It was determined that the flooding of pondweed in Nansi Lake has been alleviated in recent years, but the rapid increase in pondweed in part of Nansi Lake remains a challenging management issue. This study provides practical tools and methodology for the innovative remote sensing monitoring of submerged vegetation. Full article

Concrete cracks pose significant threats to concrete structures, causing immediate strength loss and leading to gradual erosion that compromises structural integrity. Therefore, accurate and automatic detection and classification of concrete cracks, along with the evaluation of their effects on target structures, are critically important. This study focuses on the No. 3 Huaiyin pumping station, a large-scale hydraulic structure on the Eastern Route of the South-to-North Water Diversion Project in Jiangsu, China. First, relevant field test literature is reviewed, and the finite element method is applied to investigate the effects of an existing crack on the No. 2 supporting wall. Using thermomechanically coupled numerical simulations, the distribution of tensile stress in the supporting wall is reported in two cases: without a crack and with an existing crack. The findings indicate that the increase in tensile stress due to the existing crack is relatively small and can be considered negligible for the No. 2 supporting wall. Next, the pretrained YOLOX network for the detection and classification of three types of cracks is proposed and retrained using collected concrete crack datasets. The mean average precision of the retrained YOLOX network for all three types of cracks reaches 80%. Finally, the retrained YOLOX network is applied to detect and classify cracks at the No. 3 Huaiyin pumping station. This automatic detection and classification approach will enhance the high-quality management of the pumping station because it is labor-saving and easy to deploy. Full article

The Middle Route of the South-to-North Water Diversion Project is a critical infrastructure that ensures optimal water resource distribution across river basins and safeguards the livelihood of people in China. This study investigated its effects on the land surface temperature (LST) and fractional vegetation coverage (FVC) in the Danjiang River Basin. Moreover, it examined the spatial and temporal patterns of this project, providing a scientific basis for the safe supply of water and ecological preservation. We used the improved interpolation of mean anomaly (IMA) method based on the digital elevation model (DEM) to reconstruct LST while FVC was estimated using the image element dichotomous model. Our findings indicated a general increase in the average LST in the Danjiang River Basin post-project implementation. During both wet and dry seasons, the cooling effect was primarily observed in the south-central region during the daytime, with extreme values of 6.1 °C and 5.9 °C. Conversely, during the nighttime, the cooling effect was more prevalent in the northern region, with extreme values of 3.0 °C and 2.3 °C. In contrast, the warming effect during both seasons was predominantly located in the northern region during the daytime, with extreme values of 5.3 °C and 5.5 °C. At night, the warming effect was chiefly observed in the south-central region, with extreme values of 5.8 °C and 5.9 °C. FVC displayed a seasonal trend, with higher values in the wet season and overall improvement over time. Statistical analysis revealed a negative correlation between vegetation change and daytime temperature variations in both periods (r = −0.184, r = −0.195). Furthermore, a significant positive correlation existed between vegetation change and nighttime temperature changes (r = 0.315, r = 0.328). Overall, the project contributed to regulating LST, fostering FVC development, and enhancing ecological stability in the Danjiang River Basin. Full article