Abstract:To conduct a comprehensive evaluation of resource utilization efficiency, an efficiency assessment framework that combined multi-regional input-output analysis and data envelopment analysis was proposed. This framework was employed to calculate the water, energy, and food footprints on the consumption side of cities in Guangdong Province. On this basis, input-output efficiency under the influence of inter-regional trade was assessed from the perspective of the water-energy-food system. The findings indicate that the cities’ water, energy, and food footprints on the consumption side are predominantly influenced by inflows from regions outside the province, followed by local consumption footprints. Other cities within the province receive a relatively negligible proportion of trade-implied resources. The spatial distribution characteristics of the water-energy-food system efficiency and the water, energy, and food footprints on the consumption side converge, primarily exhibiting a decreasing trend from the The Pearl River Delta region to the exterior. By taking into account the impact of inter-regional trade on water, energy, and food consumption, the efficiency of most cities has been improved, and the overall efficiency of the region has increased. Among the cities, Shenzhen and Zhongshan have demonstrated optimal input-output allocation, while the remaining cities have exhibited varying degrees of input redundancy, with Guangzhou exhibiting the greatest potential for resource savings.

Abstract:By using simulation data of precipitation and temperature in the Huaihe River Basin from 1985 to 2014 from 22 global climate models (GCMs) of the coupled model intercomparison project in phase 6 (CMIP6), the simulation performance of GCMs was comprehensively assessed by means of a rank score method with seven indexes selected, and the sensitivity of the scores to each index was analyzed. The spatial simulation performance of the selected optimal GCMs was evaluated. The results reveal significant differences in the simulation performance of monthly average precipitation and temperature in the Huaihe River Basin among the models. Overall, the GCMs perform better in simulating temperatures, but there is a general overestimation of monthly average precipitation. The top five models with the best comprehensive rank score are EC-Earth3 (7.83), EC-Earth3-Veg (7.66), ACCESS-CM2 (7.62), TaiESM1 (7.27), and FGOALS-f3-L (7.20). The rank score results for precipitation are most sensitive to the standard deviation, the statistics of Mann-Kendall trend analysis ( z ), and the slope of Mann-Kendall ( β ), while those for temperature show high sensitivity to z and β . Different combinations of rank score indexes moderately influence the scores. The EC-Earth3 model, identified as the most optimal, accurately reproduces the spatial distribution of precipitation but performs slightly less effectively for the spatial distribution of temperature.

Abstract:To study the spatiotemporal characteristics of groundwater storage changes in the hilly areas of Jiangxi Province, based on the gravity recovery and climate experiment (GRACE)/GRACE-FO satellite inversion data from 2003 to 2023, a spatiotemporal evolution analysis framework of groundwater integrating downscaling reconstruction and trend identification was constructed, revealing the pattern of changes in groundwater storage anomalies (GWSA). The high-resolution reconstruction of GWSA was carried out through a deep learning model. The long-term trend component was extracted using seasonal-trend decomposition using LOESS (STL). The groundwater change trend and its significance were identified by combining the Mann-Kendall test and the Theil-Sen slope estimation method. The results show that the reconstructed high-resolution GWSA data clearly reveal the spatiotemporal evolution characteristics of groundwater storage in the hilly areas of Jiangxi Province; after STL, the sequence shows a significant long-term trend and stable seasonal fluctuations. From 2003 to 2023, the groundwater level in the entire province has risen slowly, and the overall long-term trend shows an evolution pattern of “recovery in northeastern and central regions but continuous depletion in southern regions”. Notably, Ganzhou City in southern Jiangxi exhibits a significant decline in groundwater storage, making it a representative groundwater-deficit zone. Groundwater variations exhibit compound characteristics, including regional disparities, phased evolution, and intensified high-frequency anomalies, indicating that the system remains unstable and is in a critical state vulnerable to further depletion.

Abstract:Traditional reasoning formula methods and instantaneous unit hydrograph methods are difficult to reflect geomorphological features and land use changes in design flood calculation. To address this issue, a new design flood flow concentration calculation method, namely the runoff curve number (SCS) geomorphologic general unit hydrograph method, was proposed by considering the influence of geomorphological features and land use changes on the time of flow concentration. This method was coupled with the SCS model to establish a complete flow generation and concentration model, and the Shangbu River Watershed in Hangzhou City was taken as an example to verify the method. The verification results show that compared to traditional reasoning formula method and instantaneous unit hydrograph methods, the SCS geomorphologic general unit hydrograph method is more reasonable for calculating design floods in small watersheds within urbanized areas, as it better reflects the watershed’s geomorphological features and adapts to land use changes. Scenario analysis further reveals that the changes in underlying surface conditions caused by urbanization will lead to an increase in design flood volume and flood peak.

Abstract:To enhance the flood disaster response capability of Changchun City, a comprehensive evaluation indicator system for flood disaster response capability was constructed based on the pressure-state-response conceptual model. This system deconstructed the urban flood disaster system into three subsystems: pressure (P), state (S), and response (R), corresponding to disaster causes, loss status, and response measures, respectively. A total of 4, 6, and 4 core evaluation indicators were carefully selected for each subsystem. The entropy weight method was applied to calculate the temporal weights of each subsystem in Changchun City from 2002 to 2021, and the coupling coordination degree (CCD) model was used to analyze the dynamic coordination relationship between the S subsystem and the P and R subsystems. The results indicate that the P and R subsystems exhibit significant linear growth trends, reflecting increasing disaster-inducing pressures and enhanced response capabilities in the city, while the S subsystem does not show a clear trend. During 2010, 2013, and 2017, varying degrees of imbalance or declines in CCD have been observed between the S subsystem and the P and R subsystems, which closely coincide with relatively high precipitation levels during those years. The urban flood disaster response capability is significantly influenced by heavy rainfall, necessitating the synergistic integration of engineering and non-engineering technical strategies, as well as the optimization of urban planning, construction, and management strategies, so as to improve system coordination and disaster response effectiveness.

Abstract:By taking the North Bund area in Shanghai’s Hongkou District, the core built-up area, as the study region, a 1D-2D coupled model integrating pipe network topology optimization and surface micro-topography refinement was developed to precisely simulate rainstorm waterlogging processes in urban high-density areas. The model’s reliability and applicability were dynamically validated using multiple recorded storm events from 2020 to 2024. Based on this model, two drainage system optimization schemes for the North Bund area were evaluated (Scheme 1: adding new main stormwater pipelines + upgrading the riverside pumping station; Scheme 2: retrofitting main pipelines + enhancing the efficiency of existing pumping stations). Results indicate that the constructed 1D-2D coupled model accurately simulates rainstorm waterlogging processes in urban high-density areas under various rainfall conditions. Under the design rainstorm scenario with a 10-year return period, Scheme 1 achieves a 52.5% reduction in overflow nodes and a 44.6% decrease in inundated area, demonstrating superior system resilience compared to Scheme 2 (47.3% overflow nodes reduction and 42.2% inundation area reduction)

Abstract:To address the issues of the large amount of data required and the high difficulty in obtaining data during the modeling process of hydrodynamic water quality models, a method based on hydrological approaches for solving the basic equations of one-dimensional water quality models was proposed. This method substituted river topography and flow velocity data with Muskingum method parameters K and X for river confluence in hydrology. Moreover, coupled with the basic equations of the one-dimensional water quality model, a river pollution confluence model based on the Muskingum method was developed. Since taking a constant value for K is unreasonable for calculating pollutant propagation time in the developed model, the functions of K and X relative to flow rate Q were derived to solve this problem, and the nonlinear Muskingum model was coupled with the one-dimensional water quality model to build a river pollution confluence model based on the nonlinear Muskingum method. The verification results of the Dapuling-Changtaiguan section of the upper reaches of the Huai River show that the river pollution confluence model based on the nonlinear Muskingum method has ensured accurate prediction of peak time compared with the river pollution confluence model based on the Muskingum method. At the same time, the deterministic coefficient of the pollutant mass concentration prediction results has been increased by 0.04, the root mean square error has been reduced by 0.07 mg/L, and the average absolute error has been decreased by 0.022 mg/L.

Abstract:To investigate the spatiotemporal evolution patterns of precipitation in the Hubei section of the Three Gorges Reservoir Region under climate change, 187 precipitation samples collected from October 2022 to September 2023 were utilized to analyze the stable hydrogen and oxygen isotope characteristics of precipitation. The influence of meteorological factors such as temperature, precipitation amount, and relative humidity was examined. Additionally, the HYSPLIT model was used to trace water vapor transport trajectories and identify water vapor sources. The results indicate that there are obvious seasonal variations of stable hydrogen and oxygen isotopes in precipitation in the Hubei section of the Three Gorges Reservoir Region, with relative depletion in summer and autumn and relative enrichment in winter and spring. The relationship between δD and δ 18O in the study area is δD=8.21 δ 18O+11.23( R 2=0.94, p ＜0.01). It reflects the regional wet and rainy climatic characteristics.Precipitation amount and relative humidity are the main factors affecting the stable hydrogen and oxygen isotopes in precipitation. Temperature is the dominant factor influencing d-excess. Seasonal variations are observed in the sources of precipitation for the study area. In summer, precipitation mainly comes from the water vapor of the Pacific Ocean, South China Sea, and Indian Ocean carried by the southeast monsoon and the southwest monsoon. In winter, precipitation primarily derives from the west and northwest directions of the Eurasian continent. Spring and autumn serve as transitional periods, witnessing shifts in the predominant source of precipitation between the ocean and land.

Abstract:To accurately invert the soil moisture in Anhui Province and enhance the adaptability and accuracy of machine learning models, support vector regression, extreme gradient boosting, CatBoost, random forest, AdaBoost, and Stacking model (the first five machine learning models were selected as the base models, linear regression was used as the meta-model) were used to invert the soil moisture in Anhui Province. The spatial distribution and time series of soil moisture inversion results obtained from the Stacking model were analyzed. The results indicate that, with the same input remote sensing data, the Stacking model has higher accuracy and robustness compared to individual models. The correlation coefficient between the inverted soil moisture and the measured data reaches 0.72, and the root mean square error (RMSE) is 0.05 m³/m³. The spatial heterogeneity of soil moisture in Anhui Province is relatively high. The northern region is relatively dry, with an average soil moisture of around 0.2 m³/m³. The eastern areas of Chaohu Lake and the Yangtze River region are relatively humid, with an average soil moisture of up to 0.4 m³/m³. Although the Dabie Mountain area and the southern part of Anhui Province have higher altitudes, their soil moisture is still higher than that of the Huaibei Plain, indicating that the differences in climate between the north and the south may affect the magnitude of soil moisture. Overall, the spatial pattern of soil moisture in Anhui province is an increasing trend from the northwest to the southeast.

Abstract:To quantitatively assess the fish-passing efficiency in the Laluo Fishway and identify its optimal environmental conditions, on-site observations of the flow field, water temperature, and number of passing fishes were conducted in the Laluo Fishway. A two-dimensional mathematical model of the Laluo Fishway was constructed and verified to obtain more detailed flow field data, and the diurnal and seasonal rhythms of fish-passing were analyzed. The results indicate that the Laluo Fishway experienced a fish-passing peak in April, May and July. Flow velocity is the key factor influencing fish-passing efficiency. The average flow velocity at the vertical slot between 74.8% and 81.2% of the target species wuimming speed is the most favorable condition for their upstrean migration. Water temperature is also identified as a significant factor, positively correlated with the upstream migration behavior of fishes. Futhermore, a significant threshold effect is observed with a recommendation to maintain water temperatures above 8℃. Additionally, Flow has a relatively small impact on fish behavior. A flow rate in the range of 0.4-0.8 m³/s is determined to be most favorable for fish-passing.

Abstract:To investigate the evolution characteristics of the air pocket during the geyser process, a numerical simulation of the release of an entrapped air pocket in a drainage pipe system under double-sided inflow conditions was conducted. The geyser formation mechanisms, air discharge characteristics, and air-water energy evolutions were analyzed. The results indicate that the entry and subsequent release of an entrapped air pocket into the vertical shaft trigger an air pocket-driven geyser, followed by the occurrence of a rapid-filling geyser. Depending on whether these two processes operate independently or interactively, the geyser process can be classified as either a separated type or a hybrid type. A higher dimensionless pipeline pressure difference P * or a smaller dimensionless initial air pocket volume V a* is more likely to trigger a hybrid geyser process. The air pocket discharge ratio during the air pocket-driven geyser is approximately 2%-47%; it first increases and then decreases with increasing P *, and it decreases with increasing V *a. The air pocket discharge ratio during a rapid-filling geyser is approximately 0-5%, and it is minimally affected by P * and V *a. During the geyser process, the peak kinetic energy of the air occurs in the air pocket-driven geyser stage, while the peak kinetic energy of the water in the vertical shaft occurs in the rapid-filling geyser stage. The geyser intensity decreases with increasing P * and increases with increasing V *a. An air pocket-driven geyser occurs when the dimensionless maximum kinetic energy of the air per unit mass exceeds 1.5; a rapid-filling geyser occurs when the dimensionless maximum kinetic energy of the water per unit mass exceeds 0.5.

Abstract:In order to fundamentally reduce the overtopping and failure rate of small earth-rockfill dams, a scaled-down model was established based on a small earth-rockfill dam project with an actual height of 15 m. The downstream slope protection was constructed using turf, cemented soil, and dry-laid stone masonry. The influence of different scour-resistant slope protection materials on the overtopping and failure process of the earth-rockfill dam was analyzed. The evolution law of breach shapes was studied, and in combination with the flow velocity and flow rate changes at the breach section, the effectiveness of different scour-resistant material-based downstream slope protection in resisting erosion damage was deeply explored. The experimental results show that under stable inflow conditions, the use of materials with high scour resistance, such as cemented soil and dry-laid stone masonry, in downstream slope protection significantly reduces the erosive force of overtopping water. This substantially extends the duration of overtopping and failure by 2-3 times. The maximum flow velocity at the breach is reduced by approximately 3%, while the maximum cross-sectional discharge decreases by a range of 10%-12%. In contrast, turf-based slope protection offers only modest delay in erosion damage, extending the breach duration by approximately one fold.

Abstract:To enhance the rapid response capability and operational stability of hydraulic generating units, a unit simulation model was established to investigate the damping characteristics, frequency characteristics, and stability under the novel power regulation mode of the governor derived from water turbine characteristic curves. Two improved strategies for the novel power regulation mode were developed. Results demonstrate that compared with conventional power regulation modes, the novel power regulation mode exhibits greater negative damping of the units, leading to inferior stability in small-grid operations but better frequency-modulated fast-acting in large-grid operations. Both the interpolation output control strategy and the guide vane speed control strategy can effectively suppress reverse regulation of power but both partially sacrifice the system’s primary frequency-modulated fast-acting. The guide vane speed control strategy shows superior suppression of reverse regulation of power, whereas the interpolation output control strategy offers better compatibility with other governor regulation functions.

Abstract:To reveal the influence of free surface variation on the hydrodynamic loads of submarine pipelines with spiral strakes installed and verify the vortex-induced vibration (VIV) suppression effect of spiral strakes under partial detachment, hydrodynamic model tests were conducted on submarine pipelines equipped with spiral strakes. The tests investigated the changes in drag coefficient in the near-free-surface region (with a ratio of immersion depth to pipeline diameter is 1-4) and the near-false bottom region (with a ratio of bottom clearance to pipeline diameter is 1-4) under different Reynolds numbers. Additionally, the VIV suppression effect of spiral strakes was analyzed when 30% of their length was damaged.The test results show that when the submarine pipeline is immersed from a depth of four times the diameter to approaching the free surface, its drag coefficient gradually increases; when the submarine pipeline approaches the false bottom from an initial distance of four times the diameter, its drag coefficient decreases. With the increase in the Reynolds number, the suppression efficiency of VIV by the 30% damaged spiral strake exhibits a trend similar to that of the full-coverage scheme, both showing a decrease. Nevertheless, it still maintains a considerable suppression effect.

Abstract:In order to enhance underwater image quality in turbid water environments, a polarization image restoration method for concrete structures in turbid water was proposed based on laboratory underwater imaging experiments. The polarization characteristic difference between the concrete’s structural information light and backscattered light was analyzed, and the Stokes vector was used to obtain the polarization parameter image of the underwater image. The contrast-limiting adaptive histogram equalization method was then employed to enhance image contrast. Finally, the underwater polarization imaging model was utilized to achieve image restoration. Comparative experiments against ten image processing methods demonstrate that in highly turbid sediment-laden water environments, the proposed method achieves improvement rates of 252%, 561%, 241%, and 93% for the four evaluation metrics: average gradient, entropy enhancement, underwater color image quality assessment, and underwater image quality measurement, respectively. This enables the acquisition of underwater images of apparent defects in concrete structures with high contrast and clear details, making it suitable for restoring underwater images of apparent defects in concrete structures.

Abstract:Due to high residual stress at the stiffener welds on the web, shear link dampers (SLDs) are prone to fatigue damage under cyclic loading. Therefore, a new SLD with contact-type stiffeners was designed, and cyclic loading experiments were conducted to verify its hysteretic performance. The results indicate that the web shows premature out-of-plane buckling for the SLD without stiffeners, and cracks initiate early for the SLD with conventional welded stiffeners, which are detrimental to the low-cycle fatigue performance and energy dissipation capacity. In contrast, for the SLD with contact-type stiffeners, out-of-plane buckling of the web can be effectively suppressed, and residual stresse in the web caused by stiffener welds can be avoided. Consequently, the initiation and propagation of web cracks can be delayed, which significantly improves the low-cycle fatigue performance and energy dissipation capacity of the SLD.

Abstract:The shear capacity formula for deep flexural members in Appendix G of GB/T.50010-2010 Code for Design of Concrete Structures , namely the GB/T50010 formula, does not account for the influence of openings and thus cannot be accurately applied to the design of deep beams with square openings. To address this issue, the calculation method for the shear capacity of deep beams with square openings was investigated. Based on the statistical analysis of relevant test data to evaluate the reliability of the traditional method, the ultimate bearing capacity of nine groups of members was compared through nonlinear finite element simulation. The influence of opening parameters on the force performance was analyzed. At the same time, the modified formula of the GB/T50010 formula was given by using the fitting method, and the applicability of the modified formula was verified. The results indicate that the traditional empirical reinforcement method, which involves adding additional reinforcement around openings, lacks sufficient reliability. For a deep beam with square openings, the reduction in shear capacity is primarily governed by the opening position and opening ratio. Specifically, shorter vertical distances from the opening centroid to the compressive path (i.e., the line connecting the loading point and the support) and a larger opening ratio correlate with a decrease in the member’s shear capacity. Moreover, the opening behavior mainly reduces the contribution of concrete to the shear capacity of the member; the modified formula, by adjusting the concrete’s shear contribution term, can fully consider the adverse effects of single or double openings. Within a defined range of opening sizes and positions, the modified formula significantly improves the prediction accuracy of the shear capacity of a deep beam with openings.

Abstract:Shallow cohesive soil interacts strongly with the atmospheric environment, and its engineering properties deteriorate severely due to the influence of climate factors, leading to geological disasters and ecological environmental problems. In response to the above issues, a combination of bio-glue and rice straw fiber was introduced to improve the mechanical properties of cohesive soil. Through unconfined compressive strength tests and direct shear tests, the changes in the unconfined compressive strength characteristics and shear strength parameters of soil with single admixture and composites were investigated. The effects of bio-glue and fiber contents on the improvement effect of composite treatment were studied, and the effect mechanism of bio-glue and straw fiber composite modified cohesive soil was analyzed based on scanning electron microscope (SEM). The results show that due to the increase in bio-glue content and fiber content, the stress-strain curves of modified soil tend to behave as strain hardening, with a prolonged peak position and reduced post-peak stress decay. Both unconfined compressive strength and shear strength of modified soil are significantly enhanced, which mainly enhances the soil’s mechanical properties by increasing cohesion and has little effect on the internal friction angle. Bio-glue improves soil structure through surface coating, particle bonding, and pore filling, which also improves the reinforcement effect of fiber-soil interface and enhances soil’s mechanical properties by combining the network framework formed by fibers.

Abstract:To address the issues of low land resource utilization efficiency in cable trench installation and poor heat dissipation in conduit trench installation, a magnetic-thermal-current multiphysics coupled finite element simulation model of a 110 kV cross-linked polyethylene cable was constructed. The current carrying capacity of both the cable trench and the conduit trench installation methods was simulated and calculated. The effects of three methods, laying concrete outside the conduit in the conduit trench installation method, using high thermal conductivity conduits, and adding backfill materials inside the conduit, on increasing the current carrying capacity of the cable were investigated. Based on the orthogonal experiment, the backfill material was improved to obtain the optimal ratio of the backfill material. The research results show that by pouring concrete outside the high thermal conductivity conduits and adding improved backfill materials with the optimal proportion inside the conduit, the current carrying capacity of the cable can be significantly enhanced. Compared with the cable trench installation method, this approach increases single-circuit capacity by 31.64% and dual-circuit capacity by 18.49%.

Abstract:To address the issue that directly using historical datasets as input in photovoltaic (PV) power prediction models struggles to meet the required prediction accuracy, a short-term PV power prediction model, namely CSSA-LSTM model was proposed based on time-segmented convolutional dynamic time warping (CDTW) for similar day selection and the chaotic sparrow search algorithm (CSSA) for long short-term memory (LSTM) optimization. After preprocessing the data, the model identified key meteorological factors affecting power generation through Pearson correlation analysis, thereby avoiding interference from irrelevant data. It then divided time periods based on the total solar radiation sequence of the day to be predicted, applied the CDTW algorithm to each time period for selecting similar time segments, and reconstructed these segments into a set of similar days. Meanwhile, CSSA was used to optimize the hyperparameters of the LSTM model, enabling adaptive search for the optimal hyperparameters. Simulation analysis results using measured data from 2021 of a PV power station in southern China show that compared with traditional similar day methods and LSTM models optimized by the sparrow search algorithm (SSA), the similar day selection method and CSSA-LSTM model proposed in this study exhibit higher prediction accuracy and robustness.