Abstract:To explore the fusion methods of physical mechanism models and data-driven models, the implementation pathway of existing physics-guided fusion driving methods was analyzed. The research status of physics-guided fusion driving methods based on theory-guided data science (TGDS) in different fields was classified and summarized, and new classification methods, such as the physics-guided feedback fusion driving method and the physics-guided coding fusion driving method, were proposed. According to the characteristics of the hydrological modeling field, the challenges of the physics-guided fusion driving method in hydrological model construction were elaborated in detail. And the future research directions have been prospectively discussed. It was believed that the physics-guided fusion driving method based on TGDS could enhance the physical consistency of prediction results, reduce the accumulation of prediction errors, and improve the interpretability of the model, providing a feasible path for improving flood forecasting-oriented hydrological models. It could not only improve the low prediction accuracy caused by the generalization process of the mechanism model but also effectively improve the interpretability problem caused by the excessive dependence of data-driven models on samples. However, this method faces the problems of limited computing power, inaccurate extraction of multi-source data features, and inflexible parameter adjustment in its application. Therefore, in future research, differentiable modelling (DM) can be combined, or large models combined with domain knowledge graphs can be used to further explore the modeling of flood time series prediction, so as to better meet the needs of flood forecasting in complex environments.

Abstract:In order to accurately reconstruct the process characteristics of “23·7” catastrophic flood and provide theoretical support for the prevention and early warning of catastrophic floods in the Yongding River Basin, the grid-based Xin’anjiang (Grid-XAJ) model and Grid-XAJ based on saturation-infiltration double excess (Grid-XAJ-SIDE) model were used to simulate and analyze five key control sections in the Yongding River Basin: Zhaitang Reservoir, Qingbaikou, Yanchi, Sanjiadian, and Lugou Bridge. Typical flood events from 2000 to 2022 were selected for parameter calibration, and the “23·7” catastrophic flood event was used for validation. The results show that both the Grid-XAJ and Grid-XAJ-SIDE models can accurately simulate the entire process of the “23·7” catastrophic flood. In the Qingbaikou section, the determination coefficients of both models achieve Class A accuracy; at the Yanchi, Sanjiadian, and Lugou Bridge control sections, the model accuracy reaches Class B, indicating excellent simulation performance. The study demonstrates that the Grid-XAJ and Grid-XAJ-SIDE models perform well in simulating flood volume, peak flow, and peak time at the five control sections, making them effective for simulating catastrophic floods in semi-arid and semi-humid regions.

Abstract:The trend of water resources and water consumption in the Haihe River Basin and three provinces (municipalities) of Beijing, Tianjin, and Hebei in the main receiving area along the middle route of the South-to-North Water Diversion Project from 2001 to 2023 was analyzed using the Mann-Kendall test. The Spearman’s rank order test was applied to analyze the correlation between the changes in agricultural, industrial, and domestic water consumption with indicators of industrial production, agricultural production, and social economy in the three provinces (municipalities) and to explore the main reasons for the changes in water consumption. The results show that the total water resources of the Haihe River Basin and the three provinces (municipalities) exhibit an upward trend from 2001 to 2023. The total water consumption of Hebei Province has a significant decreasing trend, while the total water consumption of Beijing City and Tianjin City has a significant increasing trend. Beijing’s agricultural and industrial water consumption has a significant reduction trend, with many industrial and agricultural production indicators showing a strong positive correlation, indicating that Beijing’s industrial and agricultural water consumption is mainly affected by industrial restructuring. In Tianjin, the agricultural water consumption has a significant decreasing trend and a certain positive correlation with milk production. The industrial water consumption in Tianjin shows no significant variation. In Hebei Province, the agricultural water consumption shows a significant trend of reduction and a strong positive correlation with the sown area of crops. The industrial water consumption in Hebei also shows a significant trend of reduction, which has a certain positive correlation with the proportion of GDP in the secondary industry, but the positive correlation with other indicators of industrial production is weak. The domestic water consumption in Beijing, Tianjin, and Hebei all show strong positive correlation with population size, per capita disposable income, construction output value, and GDP ratio of tertiary industry, indicating that the increase in domestic water consumption in Beijing, Tianjin, and Hebei mainly originates from the synchronized growth of population, construction, and tertiary industry.

Abstract:To study the transformation of surface water and groundwater and during irrigation and the migration law of salts in the Hetao Irrigation District, Wuyuan County of Bayannur City in the irrigation district was taken as the research object. Isotope tracer, hydrochemical analysis method, and linear end-element mixed model were used to quantitatively evaluate the conversion amount of channeled water, groundwater, and stagnant water in the land. The results show that the proportion of the channeled water and the groundwater recharge to stagnant water in the land is 65.15% and 34.85%, respectively. The salt recharge of the channeled water and the groundwater to the stagnant water in the land accounts for 53.31% and 28.52% of the total salt of the two sources, respectively, and 18.17% of the salt remains in the irrigation district during the process of recharge to the stagnant water in the land.

Abstract:To gain an in-depth understanding of hydrological cycle processes in alpine and arid watersheds and provide scientific guidance for local water resources management and utilization, a study was conducted on the monthly variation characteristics of stable hydrogen and oxygen isotopes and Cl^- concentrations in the Golmud River. Water recharge sources were identified, water recharge contributions were quantitatively assessed using the MixSIAR model, and evaporation degrees were evaluated through the Rayleigh fractionation model. The results reveal that river water in July has exhibited significantly higher δ 2H and δ 18O values with lower Cl^- concentration compared to other months; the δ 2H and δ 18O values are the lowest in Xiaonanchuan but higher in Yeniugou across different months and gradually increase along river flow from Nachitai, while Cl^- concentration gradually increases from Xiaonanchuan at the lowest value to the east branch at the highest value; the δ 2H- δ 18O relationship point falls lower right below the local meteoric water line with the minimum lc-excess of -19.03‰. The mean water recharge elevation exceeds 4 700 m. Glacier meltwater and groundwater are primary recharge sources of river water, with an increasing precipitation contribution in July. There is a 9% evaporation loss on average along the river, peaking at ＞25% in the downstream east branch. These results demonstrate strong agreements between the variations of lc-excess and Cl^- concentration, validating the effectiveness of the evaporation evaluation method.

Abstract:To study the sources and erosion process of sediments in the Lhasa River, a systematic analysis was conducted on the grain size, minerals, and geochemical characteristics of the sediments in the main stream of the Lhasa River, as well as its tributaries, Duilonqu River and the Wululongqu River. The results show that: the average particle size of sediments in the Lhasa River is coarser (65.45% sand and 23.64% silt), and the sorting is overall poor; the skewness is mostly positive, and the kurtosis is wide, which reflects the obvious characteristics of river sand sediment. The mineral composition of the Lhasa River sediments is dominated by quartz (38.4%), K-feldspar (27.11%), and plagioclase feldspar (23.64%), followed by clay minerals, and the content of carbonate minerals is relatively low. The illite content in the clay minerals is as high as 83.4%, and the chlorite content is slightly higher than the kaolinite content. Montmorillonite content is very low. The chemical index of illite is less than 0.4, indicating that illite is mainly rich in iron and magnesium. The value of the chemical weathering index (CIA) of the sediments is low, implying that the sediments are in a state of weak and moderate chemical weathering and are dominated by physical weathering. Additionally, the chemical weathering of the sediments in the Lhasa River is not only controlled by the dry and cold climate but also affected by the rapid erosion of extensively exposed granite.

Abstract:To investigate the evolutionary trend of leaf chlorophyll under water stress and accurately characterize the relationship between water stress intensity and chlorophyll content distribution , Chinese cabbage cultivated in greenhouses of Nanjing City was taken as the research object. Hyperspectral imaging technology was employed to obtain the spatiotemporal variation characteristics of the leaf chlorophyll distribution during the water stress process. The influence patterns of water stress on the distribution evolution and degradation process of chlorophyll in Chinese cabbage were systematically analyzed, and a sensitive indicator for water stress, namely the chlorophyll content degradation trend index (De), was proposed. The results show that compared with the greenness analysis of visible light images, hyperspectral images can rapidly and accurately capture the distribution and variation characteristics of plants’ chlorophyll content, enabling precise analysis of the degradation and evolution characteristics and regularity of plants’ chlorophyll under water stress. As water stress intensifies, leaves gradually turn yellow and senesce, and chlorophyll exhibits a gradual attenuation trend from the leaf edge to the leaf center; De shows good sensitivity and accuracy to water stress in Chinese cabbage plants, and it can be used for precise early warning of crops’ water stress and assessment of water shortage stages.

Abstract:To deeply explore the characteristics of macrobenthos community in the lower reaches of the Dongwushi Reservoir of the Fuyang River, study the relationship between macrobenthos community and environmental factors, and comprehensively evaluate the water quality of the river, the composition and structural characteristics of macrobenthos community in the Fuyang River (Handan section) before flood season, during flood season, and after flood season were studied. Combined with the biological index (BI) and comprehensive water quality index, the water quality of the Fuyang River was analyzed, and the relationship between macrobenthos and physical and chemical factors of the water body was discussed by redundancy analysis; the main environmental factors affecting the characteristics of the macrobenthos community in the Fuyang River (Handan section) were determined. The results show that the average abundance of macrobenthos (26.3 ind./m²) before flood season is higher than that during flood season (13.5 ind./m²) and after flood season (14.1 ind./m²), and the change in the river’s water quantity during flood season has little influence on the structure of the biological community. Through comparative analysis, biotic index has an obvious effect on the biological evaluation and classification of water quality in the Fuyang River, and the water quality in the main city section is obviously worse than that in other sections. Before and after the flood season, dissolved oxygen (DO) and pH have significant effects on the community structure and distribution of macrobenthos in the Fuyang River, and water temperature and CODMn have significant effects during the flood season.

Abstract:To explore the water ecological health of lake and river systems in Suzhou City, the phytoplankton community structure of 20 lake sampling points and 82 river sampling points in Suzhou City was investigated. Parameters were selected to express the phytoplankton index of biotic integrity (P-IBI) in the lake, such as the number of dominant species of phytoplankton, the Simpson index of phytoplankton, the total density of phytoplankton cells, and the percentage of cyanobacteria biomass, which were then used to evaluate the water ecological health of river and lake systems in Suzhou City. The results show that during the flood season (in July) and non-flood season (in October) in 2022, 108 species from seven phyla and 97 species from eight phyla of phytoplankton were found in the main lakes, respectively. In 2023, 125 species from eight phyla and 112 species from eight phyla were identified during the flood season (September) and non-flood season (May), respectively, with the highest number of species in the Chlorophyta, followed by the Bacillariophyta. In the main rivers, 150 species from eight phyla and 130 species from eight phyla of phytoplankton were detected during the flood and non-flood seasons in 2022, respectively, and they increased to 157 species from eight phyla and 168 species from eight phyla in 2023, respectively, with Chlorophyta and Bacillariophyta being the dominant species. There are significant spatial differences in the abundance and biomass of phytoplankton functional groups at each sampling point, with higher total abundance and biomass of phytoplankton functional groups during the flood season compared to the non-flood season.

Abstract:To improve the hydraulic flow pattern and energy dissipation rate of the step energy dissipator in the double-layer pumping station for urban sewage lifting and reduce the impact on the step surface, based on the numerical simulation method, the renormalization group (RNG) k-ε turbulence model and the volume of fluid (VOF) model were used to analyze the hydraulic characteristics of the step energy dissipator. There are adverse flow patterns of the mainstream being biased to the right and “water wings” in the water flow of the step energy dissipator. To address this issue, a combined rectification optimization scheme of “diversion ramp + diversion pier + tail ramp of steps” was proposed, and its optimization effect was analyzed. The results show that the diversion ramp can effectively increase the flow on the left side of the step and improve the adverse flow pattern of the deflected flow. The diversion piers and the tail piers of the steps can reduce and homogenize the axial velocity of the water flow at the exit section of the steps and suppress the formation of “water wings”. Under the design flow conditions of the pumping station, the uniformity of the total flow distribution of the first step of the combined step energy dissipator has increased by 0.42; the maximum pressure on the left side of the horizontal plane has decreased by 17%; the maximum pressure on the right side has decreased by 21%, and the energy dissipation rate of the combined step energy dissipator has increased by 4.12%.

Abstract:To improve the accuracy of simulating unsteady hydrodynamic processes in compound river channels, a method for simulating unsteady flows in compound river channels based on physics-informed neural networks (PINNs) was proposed. The Saint-Venant equations and the 1D+ model were incorporated as physical constraints into the deep learning framework to construct a PINN model for simulating compound scenarios with overlapping flood peaks and storm surges. In addition, a transfer learning strategy was designed to achieve migration from rectangular river channels to compound river channels, and a dual-optimizer training scheme combining Adam and SGD was developed. The verification results of the example show that the proposed PINN model can effectively capture the hydraulic interactions between the river channel and floodplain, with a 31.8% improvement in prediction accuracy compared to traditional methods (RMSE is reduced from 0.085 m to 0.058 m). The transfer learning strategy based on pretraining in rectangular river channels can significantly improve the model performance, with the RMSE reduced by 34.5%; the training strategy using both Adam and SGD optimizers effectively suppresses overfitting, increasing the model’s prediction accuracy by 32.5%.

Abstract:To investigate the effects of the diffuser geometry and its connection method with the bottom of the shaft-type inlet/outlet on the outflow characteristics, a three-dimensional numerical model of the flow field was established for the upper reservoir shaft-type inlet/outlet of a pumped storage power station in China. The Realizable k-ε turbulence model was employed to calculate and analyze the influence of the diffuser geometry and its connection with the bottom of the shaft-type inlet/outlet on outflow uniformity and head loss. The results indicate that a conical diffuser with an appropriate diffusion angle is more conducive to achieving uniform flow distribution among the orifices of the shaft-type inlet/outlet and reducing head loss compared to an elliptical diffuser. Although adding an arc connection at the junction between the conical diffuser and the bottom of the orifices can reduce head loss, it increases the non-uniformity of flow distribution among the orifices.

Abstract:To investigate the impact of ship-generated waves on the erosion characteristics of the bank slope along the Pinglu Canal, a large-scale laboratory flume model testing system was designed to analyze the surface wave pressure variations and hydraulic erosion characteristics of the bank slope under five different conditions: mesh flexible revetment, square permeable concrete revetment, hexagonal permeable concrete revetment, gravel revetment, and unprotected slope. The results show that the temporal variation of the surface wave pressure on the bank slope is periodic, with the unprotected slope exhibiting the maximum negative wave pressure. The gravel revetment, due to its structural irregularity, demonstrates superior energy dissipation performance. Moreover, under high water levels and high ship speeds, a secondary wave peak effect occurs. The surface wave pressure distribution on the bank slope rapidly attenuates on both sides near the static water level. The ship speed has a significantly greater effect on wave pressure and wave height compared to water level changes. Analysis of surface erosion on the bank slope reveals that the unprotected slope mainly experiences three types of erosion forms, namely slope cracking, soil collapse, and slope scouring.Except for the gravel revetment, all other revetments show fine particle precipitation. The internal soil pressure and surface wave pressure exhibit consistent dynamic response characteristics. Based on the overall ecological benefits and erosion control effects, the gravel revetment is the optimal solution.

Abstract:According to the definition of the barrier effect of underground structures, the concept of equivalent barrier depth was introduced. Analytical solutions for the groundwater head, groundwater retention time distribution, and average retention time in the urban confined aquifer under three boundary conditions of constant flow rate, constant head, and diffuse recharge were derived. Numerical experiments were set up to verify the results, and the results show that the analytical solution is in good agreement with the numerical solution. The results demonstrate that the analytical solution is in strong agreement with the numerical solution.However, the fitting performance deteriorates due to hydrodynamic dispersion when the dimensions of the underground structure are relatively large. Moreover, the analytical solutions of the average retention time agree well with the numerical results in various simulation cases (with a relative error of no more than 5.94%). Even in the three-dimensional flow field, the derived analytical solutions can be used to estimate the average retention time of confined aquifers.Finally, the analytical solution is applied to the confined aquifer flow field before and after the construction of four subway stations in Chengdu Metro Line 2. The calculation results show that compared to the head, the retention time is more sensitive to the parameters of underground structures.

Abstract:Based on the principal component analysis(PCA)method, the African vulture optimization algorithm(AVOA), and lightweight gradient learning machine(LightGBM)model, a stress prediction model of concrete dam based on PCA-AVOA-LightGBM was constructed.PCA method was used to mine the main influencing factors of dimension reduction-based stress prediction, and AVOA was introduced to optimize the hyperparameters of the LightGBM model.Based on the stress monitoring data of a concrete dam, the PCA method was applied to vector regression machine (SVR), random forest (RF), extreme gradient boosting (XGboost), LightGBM models, and a comparative analysis was conducted with the PCA-AVOA-LightGBM model.The results show that the PCA method effectively reduces the multicollinearity among the influencing factors of each model. The PCA-AVOA-LightGBM model shows better performance in accuracy and efficiency than other prediction models and can be applied in stress monitoring of similar concrete dams.

Abstract:To address the core challenge of the invisible and intangible failure mechanisms in geotechnical and underground engineering disasters, a highly automated, integrated, and visual multifunctional transparent soil model test system was independently developed. This system integrated the functions of automated mixing and vacuum-saturated preloading for preparing transparent soil materials, high-precision image acquisition and testing using laser imaging and CCD technology, and multi-functional modular testing. Based on this system, a series of model tests was conducted, including single pile penetration, strip footing loading, slope loading, and excavation of a super-shallowly buried large cross-section tunnel. The test results clearly reveal the following key patterns: the pattern of soil disturbance around the pile and at the pile tip during pile driving, which is dominated by soil properties; the pattern of internal soil displacement distribution at different burial depths under strip foundation loading; the pattern of sliding surface evolution throughout the slope failure process, and the characteristics of settlement concentration zone development and disturbance zone expansion caused by tunnel excavation. This test system possesses significant advantages, including being non-intrusive, non-intervening. It enables full-section and full-process observation and offers visualization and digital capabilities. The system provides a novel technical approach for revealing the failure mechanisms and developing prevention and control strategies for geotechnical and underground engineering disasters such as landslides, debris flows, tunnel collapses, and ground subsidence.

Abstract:The mix ratio of thixotropic slurry in pipe jacking is mostly determined based on experience, and engineering geological conditions are hardly considered in the mechanism analysis of the correlation between slurry composition and properties. To address these issues, a pipe jacking project traversing silty clay layers in Nanjing was studied, and a slurry performance evaluation index system was established. The optimum Na₂CO₃ dosage was determined through mix ratio testing, and a grey similarity absolute correlation model was employed to analyze the correlation between bentonite, carboxymethyl cellulose (CMC), and slurry performance indexes. The results indicate that the optimal Na₂CO₃ dosage (relative to bentonite) maximizes the rheological properties of the slurry, and this percentage depends solely on the montmorillonite content in bentonite. Thixotropy serves as the most reasonable index for determining this percentage. Bentonite exhibits stronger correlations with thixotropy and fluid loss of slurry, while CMC, as a tackifier, shows a higher correlation with Marsh funnel viscosity. Both components have comparable effects on the dynamic shear force.

Abstract:To investigate the bonding property between basalt fiber-reinforced polymer (BFRP) bars and hybrid steel fiber ultra-high performance concrete (UHPC), pull-out tests were conducted to study the bonding property of BFRP bars and hybrid steel fiber UHPC. The effects of recycled tire steel fiber (RTSF) content, UHPC protective layer thickness, UHPC age, and different fiber replacement ratios on the bonding failure modes, bond-slip responses, and bonding strength of the BFRP bar-UHPC structure were examined. The results indicate three distinct bonding failure modes for the structure include pull-out failure, splitting failure, and combined pull-out and splitting failure. The ultimate bonding strength of the BFRP bar-UHPC structure gradually increases with greater UHPC protective layer thickness and longer UHPC age. Specifically, increasing the RTSF content from 0% to 3% enhances the ultimate bonding strength by 42.3%. However, a slight decrease in ultimate bonding strength is observed as the RTSF content increases. Based on the experimental results, a bond-slip constitutive model for the BFRP bar-UHPC structure is proposed. The model curves are in good agreement with the experimental curves.

Abstract:To enhance the timeliness and accuracy of storm surge forecasting in the coastal areas of Ningbo City, an intelligent storm surge prediction system using a long short-term memory (LSTM) model was developed. Based on historical typhoon records and virtual typhoon information, storm surges at tidal stations along the coastal areas of Ningbo City during typhoon events were calculated with the ADCIRC hydrodynamic model, creating a storm surge sample database. The LSTM model was applied to train the sample data of storm surges in the coastal areas of Ningbo City, and a robust and efficient intelligent forecasting model for storm surges in the coastal areas of Ningbo City was established through sample optimization and parameter calibration. The test results of No. 202212 Typhoon Muifa show that when the number of trained samples exceeds 400, the constructed forecasting model can accurately achieve short-term (1-12 hours) forecasting of storm surges in the coastal area of Ningbo City. However, when the forecast period exceeds 12 hours, there may be significant deviations between the forecasting results and the actual data.

Abstract:By taking into account the nonlinear factors of the cryogenic material and the structural geometric nonlinearities, a three-dimensional shell finite element model of the liquefied natural gas (LNG)cryogenic helical corrugated tube was constructed based on the parametric model. The influence of three axial cross-sectional parameters, namely wave height, wavelength, and thickness, on the tensile properties of the cryogenic helical corrugated tube was simulated and analyzed.The variation laws of stress distribution, strain characteristics, and tensile stiffness of the cryogenic helical corrugated tube under different parameters were discussed. The simulation results show that the axial cross-sectional parameters significantly affect the tensile properties of the cryogenic helical corrugated tube. As the wave height increases, both the axial stress and strain values increase, while the tensile stiffness decreases; as the wavelength increases, both the tensile stiffness and stress increase; as the thickness increases, the tensile load and tensile stiffness that the cryogenic helical corrugated tube can withstand both increase.