Developing new quality productive forces in water conservancy field is both an intrinsic requirement and a key focus for implementing the national “river strategy”. It addresses both current and emerging water problems, enhances basin safety and protection, and promotes high-quality economic and social development. In view of the main features and challenges in the new stage of governing and protecting the Yangtze River, we explore the pathways and principles of forming new quality productive forces covering scientific and technological innovations in ecological water conservancy, digitization and intelligence of production elements, and the green transformation and upgrading of industries. Furthermore, we propose to strengthen natural-based water engineering, digital twins, water conservation, pollution and carbon emission reduction, as well as watershed management modernization to advance the ecological, intelligent, green and modernized development of the Yangtze River.
To address the ambiguity surrounding the ecological benefits of hydropower projects and the challenges in quantifying these benefits, we take the Three Gorges Project as a case study to review existing research and define the ecological benefits in hydropower projects. In line with the river ecosystem service functions, we propose an evaluation framework for the ecological benefits of hydropower project from four dimensions: supply service function, support service function, regulation service function, and cultural service function. We further construct an evaluation index system for ecological benefit, and collect relevant data for quantitative analysis. Methods such as the shadow price method are used to convert these benefits into quantifiable economic values. The results indicate that the supply service value of the Three Gorges Project reaches 104.783 billion yuan, the support service value 20.074 billion yuan, the regulation service value 83.38 billion yuan, and the cultural service value 19.556 billion yuan, totaling 227.793 billion yuan. The findings offer technical support for establishing a mechanism for valuing ecological products in the Yangtze River Basin, and enhancing market-oriented and diversified ecological compensation.
Based on observation data from 29 national meteorological stations within and surrounding Poyang Lake basin from 1960 to 2020, we investigated the regional characteristics and evolution of meteorological droughts in the basin by calculating the Standardized Precipitation Evapotranspiration Index (SPEI) in association with the run theory.The findings indicate that the frequency of monthly meteorological droughts in the Poyang Lake basin ranged from 31.7% to 34.8%. Moreover, the spatial patterns of drought frequency varied significantly across different drought levels.SPEI of the Poyang Lake basin exhibited a slight downward trend in spring and autumn, with the affected area showing a marginal increase. Conversely, opposite trend was observed in summer and winter. Regarding regional characteristics, basin-wide (29.5% occurrence) and local droughts (23.4% occurrence) were predominant seasonal droughts in the Poyang Lake basin, whereas regional (10.7% occurrence) and partial regional droughts (5.7% occurrence) occured less frequently. The run theory revealed that 50 meteorological drought events have occurred in the past 61 years. The frequency of these events decreased notably with increasing drought duration, with the longest drought lasting up to 49 months. The duration, peak intensity, and total intensity of drought events exhibited pronounced inter-decadal fluctuations. A significant linear correlation existed between drought duration and total intensity, while a notable power function relationship was observed between drought duration and peak intensity. However, no significant correlation was found between drought duration and average intensity. These findings have clarified the regional characteristics and evolutionary processes of meteorological droughts in the Poyang Lake basin, thereby providing a scientific basis for assessing drought impacts and formulating effective prevention strategies.
Quantifying the spatial differentiation of floods within a basin is crucial for effective flood control and disaster management. We analyzed daily runoff data from seven hydrological stations across different tributaries in the Poyang Lake Basin over the past 70 years by using the automatic peaks-over-threshold model and the master recession curve analysis method to extract three flood characteristics: total flood volume, peak discharge, and flood duration. We constructed a three-dimensional joint distribution for each hydrological station using the Vine Copula function and compared the flood patterns across stations by calculating joint return periods, concurrent return periods, and two conditional return periods. Our findings reveal the following: 1) The Log-Normal distribution best describes the marginal distribution of peak discharge, while the Gamma distribution most effectively fits total flood volume. 2) Gaussian Copula accurately represents the correlation between peak flow and total flood volume, whereas Gaussian and Student t Copulas are appropriate for the correlation between peak flow and duration under conditions of total flood volume. 3) The western Poyang Lake Basin is highly susceptible to catastrophic floods, characterized by higher total flood volume, peak discharge, and duration. 4) In contrast, the eastern basin can accumulate significant flood volumes quickly but does not experience prolonged floods. 5) The southern basin, however, may experience extreme peak flows given a substantial flood volume. These results offer valuable insights for enhancing flood warning systems and developing effective rated flood management strategies in the Poyang Lake Basin.
The stratification of water temperature in deep-water cascade reservoirs reduces the inflow temperature of downstream reservoir, altering the supersaturation degree of total dissolved gas (TDG) in flow discharges. With the Xiluodu-Xiangjiaba cascade reservoirs as a case study, we investigated the impact of lower-temperature inflow on the longitudinal and vertical transport processes of supersaturated TDG in deep-water reservoir via field observation in association with numerical simulation. Finds reveal that: 1) a 2 ℃ decrease in inflow temperature advances the submersion position of TDG cloud by 36.4 km, shifts the peak TDG saturation down by 55 m, and reduces its vertical influence range by 23%. 2) With a 2 ℃ decrease in inflow temperature, as the TDG cloud with a saturation over 110% transports to front of the Xiangjiaba dam, the decay rate of enveloped area decreases by 16%; in subsequent transport stage, the decay rate reduces by 44%. 3) The average longitudinal transport velocity of supersaturated TDG from the jet flow zone to the interflow zone plunges by 92%. (4) As inflow temperature reduces by 2 ℃, the peak and mean TDG saturation of the outflow from Xiangjiaba’s surface orifices reduce by 3.2 and 4 times that of the outflow from power generating set, respectively. (5) The compensation effect of temperature reduction on the safe water depth threshold for fish can be quantified as 0.20 m/ ℃. The findings provide scientific support for ecological dispatching of deep-water reservoirs during flood seasons.
To assess the health risks associated with heavy metals in Wuhu’s inland waters, we selected sampling sections in three typical urban rivers in Wuhu to test the concentrations of six heavy metals—Cr, Cu, Mn, Ni, Pb, and Zn. We used a health risk model to evaluate the potential risks these metals pose to human health. Analysis of water samples revealed that Mn and Ni exceeded Class III water quality standards (according to the Environmental Quality Standard for Surface Water (GB3838—2002)), while Cr and Pb also surpassed the standard at certain locations. Principal component analysis identified that Cu, Ni, Mn, and Zn are influenced by industrial and domestic sources, Pb is associated with traffic, and Cr is affected by both natural geological factors and human activities. The health risk assessment indicated no non-carcinogenic risk for the six metals overall. However, there was a non-carcinogenic risk in the Huicheng River Channel and the Zhongshan South Road Channel, and a carcinogenic risk for Cr and Ni through direct intake pathways. These findings offer guidance for measures and recommendations to mitigate heavy metal pollution in Wuhu’s urban inland waters and ensure safe drinking water for residents.
To elucidate the community structure characteristics of metazoan zooplankton in Da’ao Reservoir and provide foundational data for assessing aquatic ecological health, we conducted two ecological surveys in August (wet season) and November (dry season) of 2021. The results are as follows: (1) We identified 26 species of metazoan zooplankton in Da’ao Reservoir, including 13 species of rotifers, 4 species of cladocerans, and 9 species of copepods. Dominant species included Keratella cochlearis, Polyarthra trigla, Diurella dixonnuttalli, Trichocerca pusilla, Pompholyxophrys trichocerca, Cylindrical Trichocerca, and Bosmina sp. (2) The density and biomass of metazoan zooplankton were higher during wet season (August) compared to dry season (November). (3) The average Shannon-Wiener index for metazoan zooplankton was 0.88 in wet season and 1.05 in dry season. Principal Coordinates Analysis (PCoA) revealed spatial distribution differences in the community structure during wet season; (4) Redundancy Analysis (RDA) indicated that the cumulative variation in species-environment relationships explained 62.4% and 65.1% of the total variation in wet and dry seasons, respectively. The permanganate index emerged as the primary driving factor influencing changes in the community structure of metazoan zooplankton in Da’ao Reservoir.
Analyzing the spatial patterns of land use and carbon stocks in the Three Gorges reservoir area (Chongqing section) over the past decade, and simulating land change trends and predicting carbon stock variations under different scenarios for the next decade, can significantly aid in optimizing regional land use patterns and formulating effective ecological policies. We employed the InVEST model and examined 13 driving factors to analyze land use changes in the Three Gorges reservoir area (Chongqing section) from 2010 to 2020 and to predict trends for 2030 under various development scenarios. We also assessed carbon stock status using the PLUS model. Results reveal that: (1) From 2010 to 2020, land use changes in the Three Gorges reservoir area (Chongqing section) were primarily characterized by the conversion of arable land, grassland, and wetlands to forest land, construction land, and water bodies. Carbon stocks in 2010 and 2020 were 426.89×106and 425.51×106 t, respectively, indicating a decline of 1.38×106 t. (2) Carbon stock distribution exhibited spatial differentiation, with lower levels in the west and higher levels in the east, lower in the south and higher in the north, and higher at the reservoir’s head compared to its tail. The spatial changes in carbon stocks closely aligned with changes in land types. Socio-economic factors, particularly population and GDP, contributed most significantly to the spatial pattern evolution. (3) By 2030, carbon stocks are projected to decrease by 0.76×106 and 8.98×106 t under natural scenario and urban development scenario, respectively, but increase by 3.72×106 t under ecological protection scenario. The primary cause of carbon stock reduction is the transition from high-carbon-density land types to low-carbon-density land types. To address these issues, future strategies should focus on creating a balanced, coordinated, and low-carbon spatial land-use pattern, planning urban growth boundaries, and prioritizing the protection of high carbon-storage areas such as the Wushan Mountain System, Daba Mountain System, and Wuling Mountain System. Additionally, restoring forests and grasslands in reservoir tail areas is crucial to preserving carbon sink functions.
Investigating the distribution characteristics of landscape ecological risks in the Chaohu Lake watershed based on topographic gradients is crucial for formulating ecological risk avoidance measures and future development strategies in small watersheds. In this study, the landscape pattern index and ecological risk index were employed to illustrate the evolution mechanism of landscape patterns and ecological risks in the Chaohu Lake watershed. The topographic position index and distribution index were adopted to enhance geomorphological descriptions, facilitating the exploration of spatial and temporal variations in landscape patterns and ecological risks within the watershed. Findings reveal that the Chaohu Lake watershed is dominated by low-grade terrain. Within low- and medium-low-grade terrain areas, human activity distribution gradually intensifies, leading to landscape irregularity. Areas with lower risk grades exhibit greater adaptability to in high-gradient spaces, whereas high-risk areas are predominantly situated in low-grade terrain. Stable change is the overwhelmingly primary change pattern of landscape ecological risk grades. Future planning for the Chaohu Lake watershed requires tailored measures to improve water ecological environments, strictly adhere to ecological redlines, and prevent excessive expansion that could jeopardize ecological integrity.
The valve shaft of Gezhouba dam ship lock is connected to the transmission gallery of the river area. During the flood season of 1993, the water level in the valve shaft increased abnormally, jeopardizing the safety of the lock’s equipment and facilities. To investigate the causes of the abnormal water level rise in the valve shaft of the Gezhouba ship lock, we examined the quantitative relationship between high-sediment-concentration flow and abnormal water levels. Using the Mike-3D numerical model, we simulated the vertical distribution of flow and sediment concentration under various discharge rates and sediment concentrations. We then calculated the relationship between the abnormal water levels in the valve shaft and sediment concentration. Based on these simulations, we explained the abnormal water level increases in the two valve shafts of the Gezhouba ship lock during 1993. Finally, we assessed the likelihood of future abnormal water level increases in the valve shafts. The modelling result reveals that the discharge and sediment concentration at approximately (30 000 m3/s, 2.85 kg/m3), (40 000 m3/s, 1.42 kg/m3), and (50 000 m3/s, 1.23 kg/m3), respectively, would lead to the abnormal water level increase exceeding 0.5 m. Following the construction of cascade reservoirs in the upstream and the implementation of China’s policy of returning farmland to forests, the probability of water level rise exceeding 0.5 m is now quite low. The findings offer valuable management insights for the safe operation of the Gezhouba ship lock.
This study introduces an approach for calculating the free flow and submerged flow through flat-trapezoidal gate. The flow calculation model was established based on BP (Back Propagation) neural network and RBF (Radial Basis Function) neural network, with multiple variables and combinations as well as single output. The input variables for the model included slope coefficient, gate opening, total head in front of the gate, hydraulic radius, contraction depth behind the gate, and downstream channel water depth. The output variable was measured flow rate. The model was trained and tested using experimental data, and extensive validation confirmed that both BP and RBF artificial neural network models demonstrated strong predictive performance. These models exhibited excellent adaptability and high accuracy in predicting flow rates for trapezoidal gates in canal systems in irrigation areas, thereby enabling precise flow control.
The pump-stopping water hammer caused by accidental power failure is one of the main threats to the safe operation of pump station project. For long-distance negative-lift pump station (LDNLPS) with downstream water level lower than upstream water level, accidental pump stop can easily cause pipeline emptying, which makes it challenging to protect against negative water hammer. It is crucial to investigate hydraulic control measures for pump stop conditions. Taking a LDNLPS as a case study, we simulated the hydraulic transients under accidental pump stop and valve rejection conditions. We compared and analyzed the water hammer protection effects of three hydraulic control schemes: air tank, air valve, and combination of air valve with air-valve surge chamber. The results indicate that using air tank requires large volume and high investment costs; air valve alone struggles to address the large negative pressure at local high points of the pipeline and may still induce bridging water hammer. Conversely, combining some air valves with short pipes to form air valve surge chamber effectively controls the negative pressure in the pipeline. In conclusion, the combination of air valve with air-valve surge chamber is economical and effective in protecting against water hammer, hence offering a viable solution for hydraulic control in similar LDNLPS projects.
In practical blasting engineering, the charge often assumes an eccentric and uncoupled position relative to the blast hole due to its own weight. This charge arrangement results in a non-uniform distribution of blasting load on the surrounding rock mass, leading to variations in explosion energy and damage patterns near the blast hole. Single-hole rock blasting structure was numerically simulated by using the HJC model and RHT model to investigate the blasting dynamic response and damage characteristics of eccentric uncoupled charge under different constitutive models. Results reveal that, in the simulation environment in this study, concentric uncoupled charges cause uniform damage around the hole. However, the damage range predicted by the RHT model is nearly twice that predicted by the HJC model. As the eccentricity coefficient increases, the HJC model shows greater damage on the coupled side of the hole, while the RHT model exhibits an uneven distribution of damage between the coupled and uncoupled sides of the borehole. In conclusion, the RHT model more accurately describes rock crack propagation in actual blasting scenarios.
To investigate the infiltration grouting mechanism of Bingham fluid in porous media, we derived formulas for calculating the apparent velocity of infiltration diffusion and the spherical infiltration grouting diffusion distance of Bingham fluid in porous media based on the fractal theory, the capillary model, and the rheological equation of Bingham fluid. We compared and validated the theoretical formulas against existing models and laboratory grouting tests. The results indicate that the diffusion radius of the grout calculated using the fractal theory-based formulas aligns more closely with experimental data compared to conventional Bingham fluid infiltration grouting formulas. These findings offer valuable theoretical support for practical grouting applications in porous media strata.
Traditional methods for treating engineering slurry are usually time-consuming, energy-intensive, and costly. In contrast, the negative-pressure drainage method is environmental friendly, easy to operate and efficient. Indoor model test was conducted to assess the feasibility of the negative-pressure drainage method for treating engineering mud. The test was performed in a self-developed test chamber equipped with a negative pressure siphon device, with the siphon tube connected to a pressure gauge for real-time monitoring of the negative pressure. The results indicate that stable negative pressure drainage can be achieved using a drainage pipe with a 4 mm inner diameter. Furthermore, both the negative pressure and drainage efficiency are positively correlated with the height difference of the drainage. This method proves more effective for treating mud with small thicknesses but is less effective for thicker mud. Overall, the negative-pressure drainage method is efficient and does not require external power, making it suitable for practical applications.
A laser particle size analyzer was employed to test the grain size of expansive soil, loess, and laterite to examine how sample mass and ultrasonic dispersion time affect the test results. A strong linear positive correlation was observed between shading rate and sample mass. Optimal conditions were determined for the laser particle size analyzer tests: shading rate between 15% and 25%, sample mass of 0.1-0.2 g for expansive soil, 0.4-0.8 g for loess, and 0.2-0.4 g for laterite, with ultrasonic dispersion times of 6 minutes for expansive soil and 2 minutes for loess and laterite. The test results are less discrete for loess and expansive soil but more discretized for laterite. In parallel tests, the maximum range in fraction content for laterite reached 10.1%. Compared to the densimeter method, the laser particle size analyzer reported lower contents of colloidal particles (smaller than 0.002 mm) and higher contents of clay particles (0.005-0.002 mm) or larger fractions. These discrepancies are likely due to the different principles underlying the two methods. The substantial differences in test results for laterite may be attributed to its unique properties. This study provides valuable insights for utilizing laser particle size analyzers in the grain-size analysis of special soils.
To investigate the deformation characteristics of retaining piles in the footwall influenced by normal faults, a case study of a foundation pit project in Shenzhen City was conducted using a comprehensive approach that included numerical simulations and field measurements. The study examined how different fault slip amounts, dip angles, and positions affect the deformation of retaining piles in the footwall’s influence zone. Sensitivity analysis and orthogonal experiments were carried out to assess the impact of these fault parameters. Results revealed that deformation of the retaining piles decreased under the normal fault, with the center of gravity shifting downward. The upper sections of the piles experienced more significant deformation compared to the lower sections. Deformation was inversely proportional to both the fault slip amount and dip angle, and directly proportional to the distance from the fault to the foundation pit. Specifically, the maximum deformation rate, r(ΔZmax/Δ), decreased exponentially with increasing fault slip amount and dip angle, but increased logarithmically with increasing distance from the fault. Sensitivity analysis showed that dip angle had the most significant impact on the maximum deformation of the retaining piles, followed by slip amount, with the fault position having the least influence. By fitting data from 64 orthogonal experiments, a strong linear relationship was established between the maximum deformation Uhm and the index η().Consequently,a predictive model for the maximum deformation of retaining piles in the footwall’s influence zone was developed, along with a corresponding predictive equation for this project. These findings offer valuable insights for deformation control in foundation pit projects located in normal fault areas with similar geological conditions.
Traditional single-model prediction methods suffer from issues like low accuracy, susceptibility to noise, and limited generalization capability. To address these challenges, we propose a novel approach for predicting concrete dam deformation by integrating the Beta Prior Principal Component Analysis (BP-PCA) and the Water Cycle Algorithm (WCA). Initially, the BP-PCA model decomposes deformation data into multiple scales, effectively reducing noise. This decomposition transforms the intricate nonlinear and non-stationary stochastic process into a set of principal components with simplified structures. Simultaneously, it enhances noise robustness by suppressing noise during the decomposition process. Subsequently, we employ the Water Cycle Algorithm optimized Support Vector Machine (WCA-SVM) to construct prediction models for each principal component. Finally, we integrate the prediction outcomes from multiple principal components to derive the final prediction result. The relative prediction error is minimized to 1.07%, with a root mean square error of 0.065. Compared to the three methods included in the comparative analysis, our approach yields over 62% improvement in prediction performance, demonstrating superior noise robustness and generalization capability.
Clinker calcination is a critical stage that influences the energy consumption in Portland cement production, and improving the efficiency of clinker manufacturing is a major concern in cement chemistry. This paper focuses on the synthesis of tetra-calcium aluminoferrite (C4AF) at low temperatures with soluble metallic nitrate and urea as raw materials using the self-propagating combustion reaction (SPCR) method. We systematically analyze the mineral phase composition, crystallinity, particle morphology, and hydration behavior of the synthesized C4AF using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and isothermal microcalorimetry. Our findings demonstrate that high-purity C4AF can be successfully synthesized via the SPCR method at 500 ℃ for 2 hours. The optimal raw material ratio by weight is ∶ ∶ ∶ =1.259∶1.0∶1.077∶2.664. CaCO3 is the only transient phase during the formation of C4AF. Increasing the urea dosage effectively raises reaction temperature and enhances the crystallinity of the synthesized C4AF. Additionally, the synthesized C4AF exhibits high hydration activity with only one peak observed in the hydration heat release curve during the initial 30 minutes. No dormancy period is observed, and the calculated hydration heat at complete hydration is 474 J/g.
The total alkali content of low-heat Portland cement, medium-heat Portland cement, and ordinary Portland cement was adjusted to 0.8% and 1.2% by adding Na2SO4 and K2SO4 respectively. The impact of alkali on the cracking sensitivity of various cement-based materials was investigated using the elliptical ring method by analyzing drying shrinkage performance, hydration product morphology, micro hardness, and micromechanics of hydration products. Results revealed that an increase in alkali content led to higher cracking sensitivity in various cement-based materials. Low-heat Portland cement exhibited strong crack resistance, and a suitable increase in alkali content could enhance its crack resistance performance. The drying shrinkage performance alone could not fully elucidate how alkali affected the cracking sensitivity of different cement-based materials. The microscopic mechanism behind alkali’s role in enhancing the cracking sensitivity of various cement-based materials included: (1) promoting the transformation of hydration product morphology and elevating micro hardness, thereby reducing the deformation adaptability of cement-based material pastes; (2) decreasing the inter-cluster bonding strength of hydrated calcium silicate (C-S-H), a component with distinct gelling properties, thereby diminishing the crack resistance of cement-based material pastes.
The bond strength between steel bars and rubberized concrete is crucial for the engineering application of rubberized concrete. To investigate the bonding properties under various loading rates, center pull-out tests were conducted under a range of loading rates (0.01 mm/s to 1 mm/s). The impacts of loading rate, rubber replacement ratio, and steel bar diameter on the bonding performance and the failure mode were examined. Results indicate that steel bar diameter significantly influences the failure mode of the pull-out specimens: specimens with 18 mm diameter bars exhibited split failures, while those with 14 mm diameter bars experienced pull-out failures. Additionally, loading rate markedly affects key parameters in the bond stress-slip curve. Based on theoretical analysis, a new model for the bond-slip relationship between steel bars and rubberized concrete under varying loading rates was proposed. Model evaluation demonstrates that predictions from this model align well with experimental results, which manifests the model’s applicability to predicting the bond stress-slip relationship between steel bars and rubberized concrete across different loading rates.
To investigate the ecological status of Shanghai’s offshore waters, we applied the water color remote sensing technology to estimate chlorophyll-a concentration. Considering the impact of BRDF (Bidirectional Reflectance Distribution Function) on inversion accuracy, we utilized LandSat-8 remote sensing data and measured water quality data in association with Lee’s model and QAA (Quasi-analytical algorithm) for BRDF correction. Results indicate that suspended sediment concentration is a major factor affecting BRDF. The angle of sunlight has minimal impact on BRDF when the sun is not vertically incident. After BRDF correction, the mean value of R2 increased by 22.2% to 0.9, whereas mean RMSE decreased to 0.74. Before the correction, chlorophyll-a concentrations in Shanghai’s offshore waters were overestimated by an average of 2 mg/m3. BRDF correction notably enhances chlorophyll-a inversion accuracy, presenting innovative insights for offshore water color inversion.
Accurate monitoring of leakage losses in water supply pipeline network is crucial for preventing water resource waste. This study proposes a multi-criteria decision analysis method to optimize sensor arrangement for monitoring the pipeline leakage loss. To address uncertainties in weights, difference thresholds, and preference thresholds in sensor arrangement, we used information entropy to screen initial sensor positions within the decision space. Based on monitoring objectives, we defined criteria for sensor arrangement optimization and applied the multi-criteria decision analysis method to rank the initial schemes. Taking into account multiple sets of parameters and different preference scenarios, we obtained the probabilistic ranking of the schemes. To validate the proposed method, we conducted simulation experiments using the k1 model of the baseline test pipe network and compared several preference scenarios. The results demonstrate that the proposed method effectively handles sequential priorities, rankings, and pairwise comparisons, avoiding the use of “black box” in selecting sensor placement scenarios.
To scientifically and quantitatively evaluate the impact of Three Gorges Reservoir operations on the runoff and ecological characteristics of Dongting Lake, we analyzed daily flow data from four hydrological stations—Chenglingji, Shiguishan, Nanzui, and Xiaohezui—spanning 1988 to 2020. We employed the IHA-RVA method and Shannon index method to assess flow evolution and its ecological effects during the trial operation phase (2003-2008) and the post-trial operation phase (2009-2020) of the Three Gorges Reservoir. Our findings indicate that: (1) During the operation of the Three Gorges Reservoir, the proportions of water flowing into Dongting Lake from the Xiangshui River, Zishui River, Yuanjiang River, and Lishui River increased, while the proportions from the three outlets of Jingjiang River decreased.(2) In the trial operation phase, the overall changes in flow rate and IHA were greater than those in the post-trial phase, with Chenglingji and Shiguishan exhibiting overall changes of 67.27% and 69.55%, respectively.(3) During the trial operation phase, a reduction in the magnitude of downstream flow increases led to a decrease in both the daily flow rate positive difference (Rrate) and the Shannon index. However, in the post-trial phase, adherence to the “Zhicheng Dispatch” rules, which aimed to ensure small and medium-sized floods downstream and increase dry-season water supply, led to an increase in Rrate and a rebound in the Shannon index. These results provide a scientific basis for ensuring water safety and ecological health in Dongting Lake.
Ecological water demand, being essential for maintaining the health of plain river network ecosystem, serves as a crucial indicator for the scientific regulation and sustainable development of water ecological environment in river basins. However, accelerated urban development and the construction of water conservancy projects have altered the hydrological characteristics of river networks and the evolution of riverbed landforms, potentially weakening river ecological functions and reducing biodiversity. Consequently, ecological water demand has become a significant research focus. This review summarizes latest progresses in the study of ecological water demand of plain river network in south China. It examines the current status of ecological water demand research, identifies prevailing challenges, and systematically analyzes hydrological and hydraulic calculation methods applicable to typical rivers in this region. By exploring the advantages, disadvantages, and applicable conditions of these methods, the review emphasizes the need to select appropriate calculation methods based on the complex and diverse conditions, and proposes to refine the research on ecological water demand zoning. This tailored approach aims to enhance the effective utilization of water resources and provide technical support for ecological environmental protection.
Assessing the health of rivers and lakes is crucial for ensuring water security and promoting sustainable development. Building upon previous research, this study employs an enhanced CRITIC-entropy weight method to calculate the index weights within a health assessment system for plateau rivers and lakes. Evaluations were conducted on the Nyang River and Zari Namco Lake, revealing the former’s health status as “healthy” with criterion layer weights assigned to social service function, “basin”, “water”, and biology in descending order. Zari Namco achieved a “very healthy” status, with criterion layer weights ordered as “water”, “basin”, biology, and social service function. The findings indicate a need for improvement in the Nyang River’s riparian vegetation width and shoreline stability, while Zari Namco requires enhancements in shoreline natural conditions, macrobenthic organism integrity, and lake trophic status. The paper concludes with several recommendations for the protection and management of both the Nyang River and Zari Namco Lake.
The Yangtze River Delta,characterized by its dense river network,constitutes a vital part of the Yangtze River Basin.To achieve integrated protection and coordinated management,this study examines the current governance of trans-provincial rivers and lakes in this region under the framework of integrated collaborative management,focusing on collaborative legislation,joint law enforcement,and coordinated judicial efforts.Although these approaches have yielded some collaborative successes in practice,challenges remain,including lack of cross-regional integrity of collaborative legislation,unclear responsibilities and authority in joint law enforcement,and insufficient judicial coordination.To address these issues,this paper advocates for transitioning the governance of trans-provincial rivers and lakes in the Yangtze River Delta to a collaborative legislative model.This model aims to clarify the roles and responsibilities in joint law enforcement,enhance judicial synergy within the basin,and establish a unified governance framework that integrates legislation,law enforcement,and justice.Such efforts will solidify the ecological foundation for managing trans-provincial rivers and lakes and promote ecological co-protection and benefit-sharing.
