[Objective] Scientific evaluation of disaster risks is crucial for improving regional disaster prevention capabilities and formulating targeted measures for disaster prevention, response, and mitigation. [Methods] Taking Fuzhou City as an example, the ground meteorological observations, historical typhoon disaster data, and 1 km-grid survey data of population, economy, buildings, and other disaster-bearing bodies were utilized. Then, the Copula function and risk matrix model were used to assess the compound disaster risks from typhoon-induced gales and storms under different return periods. [Results] The results indicated that:(1) under the scenario of 1 000-year compound return period, the design values of typhoon extreme wind speed and cumulative rainfall in Minqing County were the smallest, with the values being 26.03 m/s and 463.72 mm, respectively. Luoyuan County and Changle District showed the maximum design values under this compound return period, reaching 57.78 m/s and 1 173.87 mm, and 65.42 m/s and 1 094.27 mm, respectively.(2) As the level of return period increased, the hazard levels of disaster-inducing factors exhibited an increasing trend from the eastern coastal areas to the western mountainous areas. Moderately high and high vulnerability zones of disaster-bearing bodies were primarily distributed in the main urban area of Fuzhou City and the southeastern coastal towns, demonstrating strong spatial correlation with the concentration of population, economy, and buildings.(3) The risk of typhoon disasters in Fuzhou City generally exhibited a pattern of “high in the east and low in the west”. As the level of return period increased, disaster risks escalated from the northeastern and southeastern coastal areas to inland areas. The risks in the main urban area of Fuzhou City, Changle District, Luoyuan County, and Fuqing City were higher than other regions.(4) Under the conditions of extreme disasters(such as 1 000-year return period), medium-high and high-risk zones were mainly concentrated in the northeast, southeast, and main urban area of Fuzhou City, accounting for 34.5% of the total area of the city. [Conclusion] The risk of typhoon disasters in Fuzhou City generally exhibits a pattern of “high in the east and low in the west”. As the level of return period increases, the disaster risk gradually intensifies from the northeastern and southeastern coastal areas to inland areas. Under the conditions of extreme disasters(such as 1 000-year return period), medium-high and high-risk zones are mainly distributed in the northeast, southeast, and main urban area of Fuzhou City.

[Objective] Flash floods are one of the most common and destructive natural disasters globally. With the continuous intensification of climate change, both the frequency and intensity of flash floods have notably increased. Consequently, the significance of flash flood simulation research in the fields of disaster prevention, mitigation, and risk assessment has become increasingly prominent. However, the use of a single hydrological or hydrodynamic model often has limitations in flash floods simulation and frequently overlooks the cumulative effects of hydraulic structures, such as bridges and weirs, on flood progression in mountainous areas. This oversight can lead to the underestimation of flash floods susceptibility and potential risks. [Methods] A coupled hydrological and hydrodynamic model(CNFF-IFMS) was developed to improve the accuracy and reliability of flash flood simulations in the Zhaigang River Basin. The coupled model was further employed to quantitatively analyze the flash floods response mechanisms of three bridges(i.e., B1, B2 and B3) and one weir(W1) located in the river defense sections of the basin under multiple return period(i.e., 2 a, 5 a, 10 a, 20 a, 50 a and 100 a). Additionally, flood risk analysis and assessment for the basin were conducted. [Results] After the construction of the bridge and weir, the water levels at the cross-sections during various return periods have all increased compared to the situation without the bridge and weir, exacerbating the risk of overtopping and inducing backwater effects. According to the intensity of the backwater effects, they are ranked from strongest to weakest as W1, B1, B3, and B2. The velocities at the cross-sections during various return periods have all decreased compared to the situation without the bridge and weir, but they have generally increased the scouring of the two-dimensional area around the project. The flooded area and the range of water depth during various return periods have all increased compared to the situation without the bridge and weir. The total flooded area increased by 4.732 km² from the 2-year to the 100-year flood event, an increase of 0.046 km² compared to the situation without the bridge and weir. [Conclusion] The result indicated that the coupled hydrological and hydrodynamic model effectively reflected the basin rainfall-runoff response and its flood propagation mechanism in mountain gullies, realizing the dynamic evolution of mountain floods in time and space. Moreover, the importance of hydraulic structures such as bridges and weirs cannot be ignored, as they exacerbate the impacts of flash flood disasters to some extent. It is crucial to incorporate these structures into basin flash floods simulation studies to reduce uncertainty in the simulation result. The research can provide technical support and reference for disaster prevention and reduction in the Zhaigang River and other similar mountainous watersheds.

[Objective] Due to the impact of global climate change and rapid urbanization in China, urban flood disasters have occurred frequently in recent years, causing immeasurable casualties and socioeconomic losses. Therefore, it is important to explore the influence of different rainfall conditions on river water level to provide scientific support for urban flood control. [Methods] Based on the current sluice operation rules of the Shima River basin, coupled with MIKE11 and SWAT models, a hydrological and hydrodynamic model of the Shima River basin was constructed. The model was employed to analyze the changes of urban river water level under different rainfall scenarios with variations in rainfall frequency, spatial distribution, and temporal processes, and to explore the impacts of different rainfall conditions on the water level of the Shima River estuary. [Results] The result showed that: continuous and concentrated rainfall in the basin caused water levels at the estuary sluice to exceed the 4.5 m alert level by 13%, while intermittent concentrated rainfall caused an exceedance of 5%. The number of sluice operations at Qiling Sluice under concentrated rainfall was 7 times higher than under dispersed rainfall conditions, and widespread heavy rainfall across the basin caused the estuary water level to reach the 4.5 m warning level multiple times. [Conclusion] The findings indicate that:(1) the simultaneous occurrence of multiple rainfall events, widespread heavy rainfall, and concentrated rainfall of short duration and high intensity increases the risk of flooding in the Shima River basin.(2) Concentrated rainfall and widespread heavy rainfall across the basin have the greatest impact on sluice operation.(3) The greater the rainfall frequency, concentration, and intensity, the greater the impact on the water level at the estuary sluice. Only heavy rainfall in the upper basin causes a rise in the estuary water level, and only heavy rainfall in the lower basin or moderate rainfall across the basin has minimal impact on the estuary water level. The hydrological and hydrodynamic model of the Shima River basin established by the study, which analyses the changes of water level at the estuary sluice under different rainfall conditions, can be used as a reference for the urban flood control and flood control scheduling in the Shima River basin.

[Objective] The ongoing urbanization and economic development in China have led to factors that have exacerbated the problem of urban waterlogging. These include the improper placement of drainage pipes, the inefficiency of drainage infrastructure, and the expansion of impervious surfaces. To further promote the digital and intelligent development of sponge cities, this study analyzes the research progress and development trends in the construction of smart sponge cities. [Methods] Firstly, relevant literature in recent years was reviewed to explore the connotation, fundamental characteristics, and development of smart sponge cities. Secondly, Internet of Things technology, its architecture, and key technologies used in the construction of smart sponge cities were highlighted. Finally, the problems and shortcomings of the current research and development of smart sponge cities were explained, and relevant suggestions for future development were given. [Results] The research found that in the process of collecting the underlying information of the smart sponge city, technical challenges remain, such as the durability of the sensor and the transmission of wireless communication technology with low power consumption. At the same time, various technological method, including Internet of Things technologies, geographic information system, building information modeling, big data mining and analysis, and digital twins, have broad application potential in sponge facility monitoring and emergency management. [Conclusion] Suggestions for overcoming the challenges in the development of smart sponge cities are as follows: comprehensive standards and technical specifications need to be established; cross-departmental coordination mechanisms should be created to enhance communication efficiency. Secondly, it is important to overcome core technological challenges and explore technological innovation. Finally, in the process of achieving smart construction, sponge cities need to focus on digital information security and explore diversified financing channels to reduce costs and increase efficiency. The construction of smart sponge cities is a development trend in China aim at accelerating the smart transformation of sponge city infrastructure.

[Objective] With the intensification of climate change, the effects of thermal stratification in reservoirs and water temperature fluctuations in downstream river channels on aquatic ecosystems have become critical issues in water resource management. This study examines Longyangxia Reservoir to investigate the effects of climate change and reservoir operations on the stability of water temperature stratification and the ecological impacts of discharge water temperatures on the ecosystems of downstream river. [Methods] Using the CE-QUAL-W2 hydrodynamic model, simulations were conducted based on four socio-economic pathways representing future climate change scenarios and two reservoir operation strategies. These simulations examined the water temperature and discharge water temperature of Longyangxia Reservoir. [Results] The result showed that:(1) under climate warming and low water level operations, the average thermocline thickness of Longyangxia Reservoir was 15.57 m, with an average thermocline strength of 0.55 ℃/m and a stable stratification period lasting from 244 to 281 days. Under high water level operations, the average thermocline thickness was 20.57 m, with an average thermocline strength of 0.37 ℃/m and a stable stratification period lasting from 251 to 288 days.(2) Under the conventional pathway(SSP-8.5), the temperature difference index between the discharge water temperature and the downstream river water temperature before reservoir construction was 45.66 ℃·d and 12.39 ℃·d under different operation strategies, both showing the minimum values.(3) Under the conventional pathway(SSP-8.5), the discharge water temperature reached the optimal reproduction temperature for Gymnocypris eckloni approximately one month earlier. [Conclusion] The result highlight that climate change significantly affects the water temperature characteristics of the reservoir-river systems, suggesting that effective operation strategies are essential for addressing climate change.

[Objective] Under the influence of climate change and human activities, the Yellow River Basin is increasingly facing contradictions between the ecological environment and economic development. This study aims to investigate the ecosystem service relationships in the typical small watershed of Youfanggou in the Loess Plateau region for high-quality development of the Yellow River Basin. [Methods] Using real-time elevation data measured by drones and multi-source data such as meteorology and land use, the InVEST model was employed to explore four ecosystem services in the Youfanggou Watershed: water yield, soil retention, carbon storage, and habitat quality. The Pearson correlation coefficient was used to calculate the correlation coefficients among the four ecosystem services to clarify their interrelationships. Additionally, the spatiotemporal variations in the trade-offs and synergies of ecosystem services based on different land types were studied to identify multiple ecosystem services in the research area. [Results] The results showed that from 2001 to 2020, water yield and soil retention services in the Youfanggou Watershed initially increased, then decreased, and finally increased again, while carbon storage continued to rise and habitat quality remained relatively stable. The ecosystem services mainly exhibited a synergistic relationship, with a regional trade-off relationship observed between carbon storage and water yield. Soil retention was dominant in cultivated, forest, grassland, and water areas. The hotspots of ecosystem services were mainly concentrated in the forested areas in the northern part of the watershed. [Conclusion] The results indicate that vegetation restoration has improved ecosystem services, but its impacts on different ecosystem services exhibit spatiotemporal differences, necessitating zonal management to propose corresponding protection measures. The spatial distribution characteristics of high-value areas of different ecosystem services are closely related to the land use patterns of the watershed. Optimizing the land use structure to enhance service benefits is essential when planning and managing the watershed's ecosystem services. The changes in cold and hot spots of ecosystem services demonstrate that forest land is increasingly important in providing ecosystem services. In formulating ecological protection and management strategies, the interrelationships and spatial distribution characteristics among different ecosystem services should be fully considered to achieve sustainable ecosystem development. This quantitative study of the ecosystem service functions in the Youfanggou Watershed clarifies the spatiotemporal evolution patterns of ecosystem service functions, providing theoretical support for ecological environment evaluation and sustainable development evaluation in this area.

[Objective] Understanding the driving processes of meteorological-hydrological droughts on vegetation drought after reservoir construction helps enhance monitoring and early warning systems for vegetation drought in river basins. [Methods] Focusing on the Lancang-Mekong(LM) River Basin, the evolution characteristics of meteorological, hydrological, and vegetation droughts from 1982 to 2016 were analyzed based on three drought indices: Standardized Precipitation Index(SPI), Standardized Runoff Index(SRI), and Vegetation Condition Index(VCI). Pearson correlation analysis and lag analysis were used to explore the variations in relationships between different drought indices and the variations in drought response time(DRT) before and after reservoir construction. Finally, the effects of meteorological-hydrological droughts on vegetation drought and their driving mechanisms were investigated. [Results] The result showed that during the period from 1982 to 2016, meteorological-hydrological droughts in the basin exhibited similar trends, while vegetation drought showed significant seasonal variations and a gradual inter-annual increasing trend(0.02~0.37/a). After reservoir construction, the correlation between vegetation drought and meteorological drought decreased significantly in the downstream areas, while the correlation between vegetation drought and hydrological drought increased significantly in the upstream areas, showing a negative relationship. Additionally, significant changes were observed in the response time of vegetation drought to meteorological and hydrological droughts. During the dry season, the response time of vegetation drought to meteorological drought extended by an average of 1.6 months, while the response time to hydrological drought shortened by 0.2 months in the Vientiane-Pakse region, and extended by an average of 3.2 months in other regions. During the wet season, the response time of vegetation drought to hydrological drought extended by an average of 2.6 months. Furthermore, the response time of vegetation drought to meteorological drought varied across different regions: it decreased by 2.3 months on average in the China-Chiang Saen, Chiang Saen-Vientiane, and Pakse-Mouth regions, but increased by 3.8 months in the Vientiane-Pakse region. [Conclusion] The result indicate that reservoir construction in the basin alleviates vegetation drought in the Lancang-Mekong River Basin. The findings can enhance the ecological benefit evaluation of reservoir construction and improve the understanding of the response processes of meteorological, hydrological, and vegetation droughts.

[Objective] Droughts are characterized by their slow onset and widespread impacts, posing significant threats to water resources, agriculture, and energy. Climate change has increased the frequency of droughts and thus it is important to deepen our understanding of drought impact assessment, for which the similarity analysis of droughts based on historical events is a useful tool. [Methods] Based on daily precipitation and monthly temperature data from ERA5 in Yunnan Province for the period 1980—2021, this study analyzes drought intensity, duration, and coverage area, and proposes a method for drought similarity analysis. Firstly, the run theory is employed to analyze the intensity, duration, and coverage area of historical droughts. Secondly, the 2019 drought event is selected as the case study to evaluate its evolutionary process. Finally, the distances of different characteristics between the 2019 drought event and other historical droughts in Yunnan Province are calculated for similarity assessment. [Results] By conducting the similarity assessment of the 2019 drought event and comparing the spatial variability, results show that the similarity between the targeted drought event and identified drought events is high(with a similarity measure of over 80%). [Conclusion] The drought similarity assessment method proposed in this study combines intensity, duration, and coverage area of drought events and performs well in identifying similar drought events, which can provide technical support for drought disaster assessment.

[Objective] Wind and photovoltaic(PV) complementary power generation is characterized by volatility and intermittency, which poses significant challenges to the stability and efficiency of system operation. Existing research often focuses on the analysis of wind and PV power output or capacity configuration in isolation, and there is a lack of research on the evaluation of the complementarity of wind and PV power output and the optimization of grid-connected capacity based on weather type classification. [Methods] To address this issue, wind and PV power outputs were calculated and normalized using meteorological data from Qinghai Province in 2020, and the wind and PV power output matrix was constructed. The K-means clustering algorithm was employed to classify weather types, and the indicators of complementary volatility rate and ramp rate were used to assess the complementary characteristics of wind and PV power output under different weather types from the aspects of volatility and ramping. In addition, the daily and monthly wind and PV complementary characteristics of the region were quantitatively evaluated from multiple time scales. Finally, the optimization model for the wind and PV grid-connected capacity ratio was established. The secretary bird optimization algorithm and enumeration method were used to optimize the complementary volatility rate and ramp rate to determine the optimal wind and PV grid-connected capacity ratio. [Results] The result showed that:(1) there was a significant seasonal difference in wind and PV power output in Qinghai, with good complementarity between the two in summer and autumn, making it possible to form an effective complementary power generation system.(2) Different weather types had a significant impact on the complementarity of wind and PV power, with weaker complementarity in sunny weather and relatively stronger complementarity in cloudy weather or abrupt weather change.(3) The average complementary ramp rate of all weather types was 20.74 %, much higher than the average complementary volatility rate of 1.84 %, indicating that the combined output of wind and PV power could effectively reduce the power ramp rate and enhance the reliability of the system.(4) Under different weather types, optimizing the wind and PV grid-connected capacity ratio could maximize the indicator of complementary rate and achieve the best complementary effect. [Conclusion] The research findings effectively reveal the complementary characteristics of wind and PV power output under different weather types and determine the optimal wind and PV grid-connected capacity ratio, which provides a scientific basis for the planning, construction, and operation of wind and PV complementary power generation system.

[Objective] The modelling and assessment of tropical cyclone precipitation serves as the foundation for tropical cyclone warning and risk evaluation. This paper aims to address issues such as unclear differences in tropical cyclone precipitation modelling method. [Methods] Through literature review, this paper provides a systematic review of the characteristics, progress, applicability, and representative models of four types of models, including numerical weather prediction models, statistical models, physical models, and machine learning models. A comparative analysis is conducted, followed by suggestions and prospects for the development of these four types of models. [Results] The results show that numerical weather prediction models have high reliability and are suitable for forecasting tropical cyclone precipitation. Statistical models can generate numerous simulated tropical cyclones, making them suitable for estimating precipitation return periods. Physical models, based on simplified calculations, provide a good explanation for the mechanisms of tropical cyclone precipitation. Machine learning models exhibit strong flexibility and can be integrated with other models, showing significant potential for future development. [Conclusion] In the future, in addition to further improving relevant models, it is essential to strengthen the synergy between precipitation and secondary disasters, as well as the application of new technologies in precipitation modelling. This can enable rapid and accurate estimation of tropical cyclone precipitation, providing better support for regional tropical cyclone warning and risk prevention.

[Objective] Accurate reservoir inflow data is essential for effective reservoir operation scheduling and hydrological forecasting. However, the inflow process directly derived using the water balance method typically exhibits sawtooth oscillations and contains numerous anomalous negative values. Existing general method still require further improvement in both smoothing effectiveness and applicability. [Methods] Starting with the direct cause of sawtooth oscillations in the reservoir inflow, a low-pass filtering method was used to remove the high-frequency noise in the water level data that affected the calculation of reservoir storage capacity, thereby minimizing its impact on the estimation of inflow. [Results] The result demonstrated that:(1) for the entire flow process, the low-pass filtering method for water level data showed the best performance, with only 3.20% of the calculated inflow data having negative values, an average negative value of-29.76 m³/s, and a smoothing improvement index of 0.77. The moving average method ranked second, and the five-point cubic method performed the worst.(2) For typical flood processes of different magnitudes, the low-pass filtering method reduced the impact of smoothing on the peak flow and the time of peak occurrence, while still achieving a good smoothing improvement. [Conclusion] The result indicate that the reverse deduction method of reservoir inflow based on water level low-pass filtering is characterized by its simplicity in computation and principle. While maintaining a good smoothing improvement, it significantly reduces the anomalous negative values in the inflow process. Additionally, it has a relatively small impact on the peak flow and the time of peak occurrence, which can effectively improve the rationality of the inflow deduction result.

[Objective] To assess the water conservation capacity of the Han River Basin in 2020, calculate the ecological value of water conservation services, and conduct an in-depth analysis of the spatial transfer of water conservation service values among various provinces within the basin, [Methods] quantitative evaluation of the water conservation capacity of the Han River Basin in 2020 was carried out using the distributed hydrological model SWAT and the ecosystem service assessment model InVEST. The ecological value of water conservation services within the basin was calculated using the shadow pricing method. An improved break-point-field intensity model considering hydrological characteristics was adopted to analyze the spatial transfer of water conservation service values. The improved model includes the addition of a river direction coefficient to determine the hydraulic connection, optimization of transfer pathways(adjusting the starting point of transfer and setting the maximum radius), and comparison of four different transfer method. [Results] The results show that the total water conservation volume in the Han River Basin in 2020 was 30.584 billion cubic meters, with the corresponding service value reaching 31.685 billion yuan. Among the provinces, Hubei Province had the most significant water conservation volume and service value, while Henan Province was relatively lower. In terms of spatial transfer, Shaanxi Province had the largest outflow of water conservation service values, followed by Henan and Hubei; for reception, Henan Province received the most, followed by Hubei and Shaanxi. Among these, the straight-line transfer method at the outflow outlet had the strongest transfer intensity and the largest amount of transfer; the river channel transfer method at the outflow outlet had the next strongest transfer intensity and amount; the straight-line and river channel transfer method at the inflow inlet had similar transfer intensities and amounts; the river channel transfer method at the inflow inlet had the weakest transfer intensity, and the straight-line transfer method at the inflow inlet had the least amount of transfer. [Conclusion] Through quantitative evaluation and spatial transfer analysis, the spatial distribution and service value of water conservation capacity in the Han River Basin were revealed, and a comparison of different transfer method was provided, which provided a scientific basis for basin management and ecological protection.

[Objective] In order to timely grasp the spatiotemporal evolution law of groundwater level, [Methods] based on the GRACE gravity satellite and groundwater monitoring well data from 2002 to 2022, the COK model is used to invert the changes in groundwater level in Beijing, and the reasons affecting groundwater level changes are quantitatively analyzed from the aspects of land use, climate change, and ecological replenishment. [Results] The result show that the root mean square error of the inversion result of GRACE and measured groundwater level data is only 0-10 m, indicating that the inversion result are relatively reliable. The groundwater level in Beijing has been continuously and significantly declining since 2002, reaching historical lows from 2015. Since the middle route of the South to North Water Transfer Project was introduced to Beijing at the end of 2014, the mining output of groundwater has decreased year by year, and the groundwater depth has continued to rise by 2022. The groundwater level remained relatively stable from January to February of the year, gradually decreasing from March to June, and significantly rising from July to October due to factors such as rainfall. From November to December, there is little change in groundwater level; In terms of spatial dimension, the groundwater level in the city is divided by the central axis and extension line, presenting a strip like pattern with significant differences between the north and south. The main factors affecting groundwater level changes in Beijing are rainfall(q=20.14%) and ecological replenishment(q=11.98%), which are significantly greater than land use types(q=3.96%). [Conclusion] The results of this study have important practical significance for understanding the evolution laws of regional water cycle under changing environments, as well as water resource management and development utilization. They can provide effective support for scientific evaluation and rational utilization of groundwater.

[Objective] High-precision deformation prediction during the whole life cycle is a key method to evaluate the service behavior of dams and ensure the safe operation of dams. The current prediction model has problems such as insufficient correlation analysis of data feature, low prediction accuracy of short time series data, neglecting the continuous growth properties of the time series, and easy to fall into the local optimum in model training. [Methods] Therefore, a dam dynamic deformation prediction model is proposed, which utilizes the long short-term memory neural network(LSTM) to capture the long-term and short-term dependence of time series, couples the Kolmogorov-Arnold Networks(KAN) mechanism to improve the fully connected layer structure of the network to enhance the ability to characterize the complex data relationship of long and short time series, and adopts multi-strategy improved Harris Hawks optimization algorithm(IHHO) to explore the optimal combination of hyperparameters, so as to optimize the model structure, solve the gradient problem, accelerate the training convergence and improve the prediction performance. [Results] Examples show that the prediction accuracy and generalization ability of the model for short and long time series are better than other deep learning models, and the convergence speed is superior to other intelligent optimization algorithms, and the improvement effect of KAN mechanism on the short time series prediction is more obvious. [Conclusion] The model has good robustness and applicability, which can provide technical reference for the dynamic safety monitoring of the whole life cycle of dams.

[Objective] Termites nests within earth and rock dams severely damages the integrity of the dam structure. Their complex nest structure under variable water levels can significantly change the seepage characteristics and stress distribution inside the dam body. However, there is a lack of clear understanding of the extent to which different parts of the dam body are affected by the nests. [Methods] Taking the auxiliary dam of Baiguishan Reservoir as an example, six monitoring points were selected upstream and downstream of the dam. Numerical simulations on the damage of termitarium to earth and rock dams were conducted, and the influence on the hydraulic characteristics and stability of the dam were analyzed. [Results] The findings show that:(1) Under design flood level conditions, the termitarium system has a significant impact on the dam's seepage and stability characteristics. This phenomenon is primarily related to the water level on the upstream slope and the location of the termite tunnel ventilation openings, rather than the position and size of the termitarium itself.(2) The presence of termite tunnels creates seepage channels within the dam body, allowing water to flow through the dam more rapidly, which result in an elevated phreatic line. This, in turn, reduces the matric suction of the dam. Additionally, an increase in the diameter of the termite tunnels will slow down the rate at which the phreatic line drops, thereby increasing the risk of seepage failure.(3) When the water level is high, the rate of increase and the peak value of pore water pressure in the dam body are higher under the influence of the termitarium compared to a dam without termitarium. The pore water pressure also shows higher sensitivity to changes in water level.(4) In the displacement field, the termitarium system mainly affects the area above the termitarium within the dam. The displacement amplitude in this area increases during the water level rise and decreases during the water level drop. Moreover, the larger the scale of the termitarium, the greater the displacement amplitude.(5) The termitarium system weakens the overall stability of the dam and leads to a decrease in the safety factor. The impact of the rate of water level rise and fall on the safety factor is more significant than the position and size of the termitarium. [Conclusion] Numerical simulation can effectively diagnose the damage level of earth and rock dams under termite damage and quickly assess the safety condition of termite-hazardous earth and rock dams. This study combines termite damage with earth and rock dam safety evaluation by observing the structural and performance changes of the dam and quantifying the damage caused by termites to the dam, revealing the hydraulic destruction mechanism of the dam termitarium, and providing support for the safety evaluation of earth and rock dams affected by termites.

[Objective] Rock-filled concrete(RFC), characterized by low hydration heat temperature rise and rapid construction speed, meets the dam construction requirements in high-altitude cold regions. On-site monitoring of temperature variations inside the lifts during the construction in high-altitude cold regions can provide basic data and references for its design and construction in such environments. [Methods] To investigate the temperature variations and distribution patterns of RFC dam regions under integrated thick-layer placement in high-altitude cold regions, on-site tracking and monitoring were conducted on the Yebatan secondary dam(crest elevation: 2 730.0 m), with a total of 83 temperature measurement points deployed across 13 construction lifts. [Results] The results showed that the average hydration heat temperature rise of the self-compacting concrete(SCC) in the erosion-resistant layer was 24.77 ℃, significantly higher than the 10.94 ℃ of the RFC in the dam body. When the placement layer thickness increased by 0.5 m, the average hydration heat temperature rise of C25-RFC changed by only 0.02 ℃, while that of C30-SCC increased from 24.33 ℃ to 27.24 ℃, a rise of nearly 3.0 ℃. The placement temperature and hydration heat temperature rise showed minimal differences between internal(30 cm deep) and external(5~15 cm) measurement points in rock-filled concrete, with values gradually converging over time. [Conclusion] The findings reveal that:(1) under integrated thick-layer placement of erosion-resistant layers in high-altitude cold regions, local high-temperature zones and steep temperature gradients are typically distributed on the upstream and downstream surfaces of these layers.(2) A moderate increase in placement layer thickness has little effect on the hydration heat temperature rise of the RFC dam body but has a significant effect on the SCC in the erosion-resistant layers.(3) When the concrete grade and placement layer thickness remain constant, the hydration heat temperature rise of the erosion-resistant layers is relatively stable, and the peak temperature can be controlled by adjusting the placement temperature to meet design requirements.

[Objective] Studying the seepage and consolidation processes of red mud storage facilities under complex recharge conditions in karst areas is highly significant for preventing and controlling leachate seepage in these regions. [Methods] Using the Zhatang Red Mud Storage Facility in Guizhou as a case study, a self-developed experimental apparatus for simulating consolidation and seepage in tailings ponds was built, and a method was proposed to measure the red mud consolidation process. Simulation experiments on the consolidation and seepage of the red mud storage facility were conducted under three typical conditions: natural consolidation of red mud tailings, lateral groundwater recharge, and surface recharge. [Results] The results show that:(1) Under conditions of seepage without recharge, the red mud gradually completes consolidation within the storage facility, and the leachate is entirely discharged in a short time.(2)Under lateral recharge conditions, the red mud storage facility exhibits typical pore-fracture dual media properties. Groundwater rapidly moves along fractures formed within the facility to various parts, supplying water for the pores in the red mud to absorb. In the presence of lateral recharge, the degree of red mud consolidation decreases rapidly, and the subsequent consolidation process slows down, reaching an equilibrium state of slow or non-consolidation.(3)Under rainfall recharge conditions, the red mud inside the storage facility rapidly infiltrates along fractures. During rainfall recharge, the degree of red mud consolidation decreases rapidly at the initial stage and then remains stable; the consolidation degree is significantly affected by drainage. [Conclusion] Overall, the consolidation and seepage characteristics of red mud within storage facilities under complex recharge conditions in karst areas were investigated, providing support for targeted prevention of leachate seepage.

[Objective] The specific implementation of blockchain technology in water conservancy project faces many difficulties, while the potential obstacles continue to widen the gaps in the aspect of the implementation, and then assessing the obstacles to the implementation of blockchain technology in water conservancy project is particularly important for narrowing the gaps. [Methods] Firstly, the factors of the obstacles to the implementation of blockchain technology in water conservancy project are identified based on the literature study, expert interviews and the theoretical framework of technology-organization-environment. Secondly, the hierarchical structure of the obstacles to the implementation of blockchain technology is analyzed with the fuzzy interpretative structure model modeling method. Finally, the method of the interval type 2 fuzzy AHP is used to rank the weight of each obstacle factor. [Results] The results show that the obstacle factors EB7 and OB2 are at the bottom of the structural model and the obstacles with the largest weight are EB1, TB2, TB1 and EB2. [Conclusion] The lack of special policy support and the lack of willingness to adopt new techniques are the most fundamental obstacles, while the trust, cooperation and game among benefit-related parties, the expansion challenges of water conservancy data, the security risks of water conservancy data and the uniqueness of water conservancy project are the important factors to constitute the obstacles. The adopted quantitative analysis method provides a new insight for analyzing the obstacle factors. The study findings can provide a technology-organization-environment theoretical framework-based reliable solution for overcoming the obstacles to implement the blockchain technology to water conservancy project, so as to promote the development and application of blockchain technology in water conservancy project and provide the relevant decision support for the managers concerned.

[Objective] To investigate the effects of freeze-thaw damage and excavation unloading damage on the mechanical properties of rock masses in cold regions. [Methods] Indoor mechanical tests were conducted on sandstone considering unloading and freeze-thaw damage factors in different order of action, and the mechanical properties and energy evolution laws of sandstone were analyzed. [Results] The result showed that the degradation of uniaxial compressive strength and elastic modulus of rock samples is most significant under the condition of “unloading freeze-thaw”. The fracture morphology gradually evolves from shear failure to tensile shear composite failure with increasing cycle times, and the main failure surface and tensile cracks are prone to develop along macroscopic freeze-thaw cracks. Damage increases the dissipated energy and its proportion during the process of rock sample failure, while reducing the energy storage limit. [Conclusion] The initial pore state of rock samples during freeze-thaw has a significant impact on the degree of degradation, and the feedback degree of early freeze-thaw damage to unloading damage is lower than that of early unloading damage to freeze-thaw damage. The damage mechanism of unloading and freeze-thaw on rock samples has a direct impact on the fracture morphology, proportion of dissipated energy, and storage and release of elastic energy of rock samples.

[Objective] To evaluate the anti-fouling, anti-corrosion, and anti-biofouling performance of bionic coating technology in water ecological protection and restoration, and analyze its application effectiveness in complex water environments. [Methods] Multi-layer spraying technology was used to prepare the bionic coating, and its antibacterial performance, physical performance indicators, and safety indicators of water quality were tested to comprehensively evaluate the coating's protective ability in aquatic ecological environments. Combined with typical cases, the long-term stability and protective effect of the coating were verified. [Results] Bionic coating technology formed a dense protective layer on the surface through a multi-layer spraying process, demonstrating excellent performance in anti-fouling, anti-corrosion, and durability. The antibacterial rate exceeded 95%, VOC emissions were ≤23 g/L, and the coating remained stable in acidic, alkaline, and saline environments. Engineering applications showed that the anti-fouling rate was ≤2%, the cleaning and maintenance frequency was reduced by 1 to 3 times, and the service life of the facilities was significantly extended. [Conclusion] Bionic coating technology demonstrates excellent anti-fouling, anti-corrosion, and anti-biofouling capabilities in water ecological protection and restoration. It can effectively reduce biological pollution, extend the service life of facilities, lower maintenance costs, and provide an efficient and sustainable protection solution for hydraulic structures.

[Objective] Based on the seismic stability analysis of the foundation surface of concrete dam built on bedrock, the experimental study on static and dynamic fracture of fully graded concrete/basalt interface is carried out. [Methods] The tests were conducted in the form of cylindrical composite specimens subjected to direct tension containing preset cracks. Two loading rates were considered in the range of typical strain rates for seismic loading. The load-displacement curves of the specimens were measured, from which the fracture parameters of the full-graded concrete/basalt interface were calculated and the fracture toughness was obtained in combination with numerical simulations. [Results] The results show that the composite specimens under quasi-static loading expanded along the preset cracks, whereas the specimens under dynamic loading were deflected towards the location of the natural diagonal cracks contained in the basalt during expansion. [Conclusion] Compared with the quasi-static loading, the fracture parameters of the composite specimen are all increased. Furthermore, t the fracture parameters of composite specimens under quasi-static loading were significantly reduced compared to fully-concrete. The present study can provide a reference for the fracture properties of the fully-graded concrete/basalt interface under quasi-static and dynamic loading.