To improve the accuracy of areal mean rainfall data and solve the problems of instability of least square estimation in runoff error correction based on dynamic system response curve, ridge estimation of rainfall error based on differential response was introduced based on least square ridge estimation. The calculation of the Xin’anjiang model was generalized a system. The method was applied in flood forecast error correction in Jianyang basin with 37 historical floods chosen as test samples. The results indicate that the ridge estimation of rainfall error based on differential response has obvious correction effects in Jianyang basin, which can improve the accuracy and stability of flood forecasting.

In order to explore the evolution of rainfall at multiple time scales, this paper takes the Changtan Reservoir in Jiaojiang River Basin as an example and classifies independent rainfall events based on rainfall data from 1960 to 2019. The evolution of rainfall event elements is discussed from four perspectives of rainfall event scale, seasonal scale, changes in annual trends and interannual decadal change. The results show that the extreme rainfall events has strong rainfall and long rainfall duration; The rainfall duration of typhoon rainy season is shorter and the rainfall intensity is greater than that of the plum rainy season, and the variation of rainfall distribution is greater; The annual trends of rainfall event elements are similar between the two stations during the plum rainy season, but the annual trends of rainfall duration and rainfall intensity are significantly different between the two stations during the typhoon rainy season; The rainfall events of the two stations in the plum rainy season have a good response to El Nino events, while the annual rainfall of El Nino/PDO- in the typhoon rainy season is abnormally small, which is prone to drought. El Nino/PDO+ annual rainfall is abnormally high and is prone to appear flood disaster.

Evapotranspiration is a key process of energy exchange in the terrestrial-atmospheric system, and the selection of a suitable method for its accurate estimation is the basis and challenges to revealing the energy exchange process and the mechanism of Land-Atmosphere coupling under complex topographic conditions. Based on 60 years of meteorological data from 25 stations in the Red River Basin, China, the FAO56-Penman-Monteith method was used as a benchmark, and the MK statistical tests and Taylor diagrams were used to evaluate 8 potential evapotranspiration (PET) estimation methods from five aspeacts. The results show that the radiative methods Priestley-Taylor and Hargreaves had the best applicability, their results were closest to FAO (R²≈0.9); The temperature methods McCloud and Linacre were followed; The mass transport class methods Rohwer and Penman were worse. This study not only provided a highly adaptive PET estimation method for the Red River Basin, China, but also revealed the spatial and temporal distribution characteristics of the PET.

Affected by the changes of East Asian monsoon and human activities, the hydrological processes in the southeast coastal area have been changed, and the rational development and utilization of regional water resources are facing challenges. Taking Feiyunjiang as an example, the variable parameter Budyko equation based on the moving average treatment was constructed to analyze the runoff change in the basin, and the future runoff change trend was predicted qualitatively combined with the CMIP5 model. The results show that the time-varying Budyko model is much better than the constant parameter Budyko model in the simulation of annual runoff. The hydrometeorological elements in Feiyunjiang Basin showed an upward trend after eliminating the influence of cycle. The contribution rate of climate to runoff variation in the Feiyunjiang Basin reached 85.56%, and showed a downward trend. Compared with before 2000, the contribution rate of the underlying surface to runoff change increased by 6% from 2000 to 2020. At the same time, the influence intensity of climate on runoff change changed sharply. The influence of the underlying surface on runoff reduction was weakened. In addition, under the RCP4.5 scenario, the runoff in the Feiyunjiang Basin will show a decreasing trend in the future. The research results can provide theoretical support for regional water resources planning.

With the continuous development of the city, influenced by climate change and human activities, the runoff of urban water system has changed greatly. In order to further research the runoff trend and its main influencing factors brought by urbanization, the application of the comparison of slope change ratio in hydrological change analysis was further innovated, and the contribution rate of underlying surface to runoff change was separated from human activities. Taking Zhengzhou city as an example, combined with Mann-Kendall test method, the contribution rate of climate change factors, underlying surface factors and other human activities to runoff change was calculated. The results indicate that the measured runoff flow showed an upward trend from 1980 to 2019, and a sudden change occurred in 2008. In the impact analysis of runoff, the change of underlying surface and other human activities are the main influencing factors, and their contribution rates are 69.76% and 56.19%. According to the analysis of the main influencing factors, the main reasons are as follows: The hardening of the underlying surface increases runoff yield and flow concentration, and the population increases and the emissions increase.

Based on the runoff data of Buha River Basin and Shaliu River Basin in Qinghai Lake Basin, the annual base-flow index was obtained by using the filter smoothing minimum method. The temporal and spatial variation of precipitation and the evolution law of base flow in this basin were analyzed by TFPW-MK method, and the influencing factors of base flow were analyzed. The results show that the base-flow index of Buha River Basin first increases, then decreases and increases, reaching the maximum in May and the minimum in August; The base flow index of Shaliu River Basin fluctuates and reaches the minimum in April. The annual average runoff in the Buha River Basin and the Shaliu River Basin showed a significant increasing trend, and both the annual average base flow and base flow index showed an insignificant increasing trend; The base flow inclination rate of the Buha River Basin is twice that of the Shaliu River Basin. The base flow sequence of the Buha River Basin and the Shaliu River Basin is greatly affected by precipitation, flow, drought index and evaporation, and the Shaliu River Basin is more significantly affected by evaporation.

With the development of deep learning and image recognition technology, monitoring the water level of urban rivers and lakes through video has become a hot research topic in recent years. In order to realize the comprehensiveness of urban river and lake water level monitoring, a method of river and lake water level identification based on Mask RCNN was proposed. The water level was obtained by the water level characters and their position relations in the video images, and it was verified by the monitoring video of the real water level station in Dongying City, Shandong Province. The results show that the probability that the comparison error between the water level identification result and the measured data was less than 2 cm was 68.5%, the probability of error less than 3 cm is 76.9%, the probability of error less than 5 cm is 93.5%, the average error is 2.1 cm, and the root mean square error (RMSE) is 3.0 cm, which meets the recognition accuracy requirements of video water gauge level in Technical Outline of Digital Twin Watershed Construction (Trial). Therefore, the model has a good recognition effect and a certain application prospect.

The lakes on Tibetan Plateau are expanding continuously, and the frequency and intensity of natural disasters (debris flow, glacial lake outburst) are increasing, which brings a series of challenges to water resources management, water disaster prevention and sustainable development in Tibetan Plateau and its downstream areas. Taking Yigong Lake as the research object, this paper establishes Tableland NDWI (TNDWI) based on 1 101 remote sensing images. Then the water surface morphology of Yigong Lake from 1986 to 2020 is reconstructed to analyze evalution process of historical water surface morphology in lake. The results show that the user accuracy of the TNDWI for the classification of plateau water bodies is higher than 96.70%, the overall accuracy is higher than 98.75%, and the Kappa coefficient is between 0.972 and 0.992, and the classification accuracy and consistency are better than the tranditional NDWI; The 2000 Yigong landslide has a significant impact on the evolution process of water surface morphology of Yigong Lake; Water surface area after dam-break reduces from 14.44±2.70 km² to 10.99±1.94 km²(P <0.001). Mann-Kendall mutation test results show that the change trend of water surface morphology has a mutation in 2000 (except in dry season); Morlet wavelet periodic analysis results show that the periodic oscillation law of lake area has gradually weakened since 2000. This study overcomes the lack of monitoring data of high altitude barrier lake, providing data basis for the ecological restoration and comprehensive treatment project of Yigong Lake as well as new idea for the quantitative study of the ecological environment in the region.

It has great guiding significance of studying the hydrodynamic distribution strong tide for Shenzhen River estuary management. The physical model of Shenzhen River was established to analyze the hydrodynamic distribution characteristics of beach and trough and the neap tide. The spring tide in dry season and typhoon "Hato" were selected as the boundary conditions in tidal optimal estuary. The results show that the tidal power of the main trough of the Shenzhen Estuary is obviously better than that of the middle beach, the flow velocity tends to increase from the downstream to Shenzhen River for the discharge section is narrower in upstream during rising tidal, the power of spring tide and ebb tide in dry season is basically the same, the power of spring tide in dry season is stronger than that of ebb tide, the estuary flow pattern is mostly affected by riverbed morphology during the low water level with a large area of open beach which made the south trough flow only. During the storm surge, the hydrodynamic force of the estuary is strong, the flow velocity of the middle beach is significantly greater than that of the dry season, the middle beach water is not flowing back to the trough for the high water level and the mangroves in the middle beach has a great influence on the flow pattern. According to the hydrodynamic characteristics and flood discharge requirements, the countermeasures for ecological beach consolidation and main channel widening in Shenzhen Estuary were put forward.

To investigate the spatial and temporal variation of terrestrial water storage in the Yellow River Basin, the inversion of terrestrial water storage in the Yellow River Basin was performed based on the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) gravity satellite data from 2003 to 2020. Besides, the Variable Infiltration Capacity (VIC) hydrological model was used to simulate the soil water changes. The groundwater storage changes between 2003 and 2014 were calculated through the water balance equation. The results show that the overall terrestrial water storage in the Yellow River Basin is in deficit during the study period, with a significant decreasing trend temporally. Spatially, the water storage is reducing from the river source to the downstream. The inversion results show that the spatial and temporal variation of terrestrial water storage in the Yellow River basin is highly correlated with the topography, climate and human activities. The results can provide a scientific basis for water resources planning and allocation in the Yellow River Basin.

The dynamic changes of the water ecological footprint and carrying capacity of the representative cities along the first Phase Project of South-to-North Water Diversion East Route Project from 2010 to 2020 were analyzed based on the water ecological footprint and carrying capacity model. The SVR model was used to predict the water ecological condition of these cities from 2021 to 2025. The results show that the per capita water ecological footprint of Shandong displays a general uptrend, and the per capita water ecological footprint of the south section of Luoma Lake and Jiaodong Peninsula is at a high level. The per capita water ecological carrying capacity in the north of Luoma Lake and Jiaodong Peninsula shows an upward trend, while in the south of Luoma Lake and across the Yellow River, it shows a downward trend, among which the south of Luoma Lake is at a high level. The water ecological deficit or surplus of the representative cities along the line began to improve in 2013, indicating that the implementation of the project has a positive effect on the improvement of ecological environment. From 2021 to 2025, the water ecological footprint of Jiangsu section will increase and the water ecological carrying capacity will decrease. With the continuous increase of water consumption in various industries, the sustainable development of this region will face a great threat. Although the water ecological situation in Shandong section is developing well, it will continue to be in a state of water ecological deficit for a period of time, and the situation of water ecological pressure is severe.

In order to evaluate the water use efficiency of the central Yunnan urban agglomeration accurately, 14 indicators were selected from five aspects of comprehensive, industrial, agricultural, living and ecological water use, and the evaluation index system was constructed. The subjective weights were obtained by analytic hierarchy process. The entropy weight method was used to determine objective weights. The game theory method was adopted to get the combination weight. The TOPSIS evaluation model was established to calculate the relative closeness degree of water use efficiency and the closeness degree of each criterion layer in central Yunnan urban agglomeration from 2011 to 2020, and the national average data was added to the evaluation sample as the criterion for judging the results. The results show that in terms of spatial distribution, Kunming has the highest water use efficiency, followed by Qujing and Yuxi, both of which are at a good level, and Honghe and Chuxiong have the lowest water use efficiency, both of which are lower than the national average water use efficiency, at a poor level; In terms of time series, except for Qujing City, the overall water use efficiency shows an upward trend. Qujing City shows a downward trend before 2016 and slowly recovers in 2016. By analyzing the causes of the changes, this paper put forward the shortcomings of water use efficiency in each city, which can provide reference for improving water use structure and water use efficiency in central Yunnan urban agglomeration.

The spatial and temporal variations of water quality in Wuxi water area of Taihu Lake are important for regional eutrophication control and water pollution control. Based on the monthly water quality data of Wuxi water area of Taihu Lake and the water quantity data of rivers entering the lake from 2010 to 2020, the spatial and temporal variation characteristics of water quality and eutrophication status of the lake were evaluated using the integrated pollution index and integrated nutrient status index. The inter-annual variation pattern and spatial pattern of major water quality indicators were analyzed, and the correlation between the water quality of the lake and the concentration and flux of pollutants in rivers entering the lake was investigated. The results show that the water quality of Wuxi water area of Taihu Lake improved significantly from 2010 to 2020, and the integrated pollution index and integrated nutrient status index of the whole lake decreased by 25% and 10%, respectively. Except for the concentration of total phosphorus concentration with no obvious change trend, the concentration of other water quality factors in the lake area all showed a downward trend. In terms of seasonal changes, permanganate index, total phosphorus, and chlorophyll-a concentrations maintained higher values in summer and autumn, while total nitrogen and ammonia nitrogen concentrations maintained higher values in winter and spring. Spatially, nutrient concentrations decreased from the northwestern and northern lakes to the southeastern and eastern lakes. The changes in water quality of rivers entering the lake from 2013 to 2020 are basically consistent with the trends of water quality in the lake area. The concentration of total nitrogen and ammonia nitrogen in the lake area are significantly positively correlated with the concentration of total nitrogen in inflow river and the flux of ammonia nitrogen into the lake, respectively. The spatial pattern response is consistent, and the exogenous input of the inflow river is an important factor affecting the spatial and temporal changes of water quality in the lake area.

Lakes are highly susceptible to eutrophication due to their long-term closed or semi-closed status and poor hydrodynamic conditions. This paper constructed a hydrodynamic-convective diffusion model with MIKE21 software by considering the influence of rainfall on the spatial and temporal distribution of TN concentration in the Yilong Lake. The model simulated the hydrodynamic conditions under different inlet opening and closing conditions and different flow diversion schemes. The improvement of TN concentration based on the flow velocity distribution of the lake flow field was discussed. The results show that the hydrodynamic conditions and the water quality of the lake can be effectively improved by setting up water diversion inlets and increasing water diversion flow. The overall effect of diverting water from the Chenghe alone is better than diverting water from the Chenghe and Longgang River together. Under the scheme of separate diversion from the Chenghe, when the water diversion flow was double, the overall flow rate of the lake was increased by 44.04% and the TN concentration decreased by 52.78%, with the best effect of hydrodynamic optimization and water quality improvement, but the efficiency of water quality improvement per unit of water recharge is reduced. This research could provide some references for similar projects.

Urban water bodies play a vital role in maintaining the urban environment and development. In order to solve the problem of low transparency of its water body, taking Yaojiang River as the research object, the effects of solar radiation, turbidity, suspended solids concentration and particle size on water transparency were analyzed by means of comparative ratio, Pearson correlation analysis, and curve fitting calculation. The results show that the light intensity, solar elevation angle and azimuth angle affect the transparency monitoring. The stronger the light is, the greater the monitoring result of transparency is. Transparency (SD) is negatively correlated with turbidity (TUB) and suspended solids concentration (SS). Pearson correlation coefficients are -0.880, -0.570. After monitoring and calculation, the median particle size (d_50%) of Yaojiang River is between 15.5 and 61.3 μm. Filtration through a filter with a pore size of 10 μm can control the turbidity of the water body within 9.7 NTU and the concentration of suspended solids within 13.4 mg/L. The transparency of the Yaojiang River can reach 80 cm, which is the minimum requirement to maintain a normal aquatic environment.

In order to explore the water quality and pollution characteristics of the main water system in Chengde area, the monitoring data of 29 sections of Chengde surface water quality monitoring station from 2017 to 2020 were selected, and the water environment quality of the main water system in Chengde area was comprehensively evaluated by single factor evaluation, comprehensive pollution index and principal component analysis. The evaluation results show that generally speaking, the overall water quality of the main water system in Chengde is good from 2017 to 2020; From the perspective of time, the water quality of the main water system in Chengde in 2019 and 2020 was significantly improved compared with 2017 and 2018; From the perspective of space, the section pollution of Gonghou and Chenggang bridges is relatively serious. The water quality of the main water system in Chengde is mainly affected by the total phosphorus, COD and permanganate index.

In order to research the growth adaptability and engineering applicability plants in the floodplain ecological restoration area in the lower reaches of the Three Gorges dam area under flooded environment, four kinds of shrub plants such as distylium chinense, myricaria laxiflora, salix variegata and rosa sp were planted and observed in the floodplain area at the same water level in the lower reaches of the Three Gorges dam area. Four shrub plants experienced a certain degree of flooding period. The results show that the survival rates of the four shrub plants were different under flooding conditions, and the plant preservation rates from high to low were as follows: salix variegata, distylium chinense, myricaria laxiflora and rosa sp. The morphological changes, plant height growth and recovery growth were observed. Among them, salix variegata, distylium chinense and myricaria laxiflora showed better flooding adaptability under flooding stress. The applicability of ecological restoration engineering of 4 Shrub plants was evaluated by weighted scoring method. The scores from high to low are distylium chinense, myricaria laxiflora, rosa sp and myricaria laxiflora. It is determined that distylium chinense can be used as the main shrub plant in the floodplain ecological restoration project.

Based on the runoff duration data of the basin in the past 50 years, the spatial-temporal evolution and ecological effects of hydrological variation in the Zuli River basin in arid and semi-arid region were studied by using cumulative anomaly analysis, M-K nonparametric mutation test, and runoff ecological index analysis with flow duration curve. The results show that since 1970, the surface runoff of the study basin was strongly affected by climate, and its runoff appeared sudden change in 1995. After studying the variation of runoff in the basin, the surface runoff decreased significantly, and the runoff in flood season and annual runoff decreased 36.9 million m³ and 32.12 million m³, respectively. After runoff variation, the ecological deficit in the study basin was obvious, and the annual proportion of runoff ecological indexes in non-flood season increased.

This paper aims at the complex flow response relationship in the short-term joint operation of Jindong-Guandi cascade hydropower stations in Yalong River basin. In order to predict the inflow response process of the Guandi hydropower station, the random forest (RF) model and support vector regression (SVR) model were combined to mine the nonlinear relationship, and compared with the traditional lag-time model and the Muskingum model. On this basis, two simulation dispatching models were established to test the applicability of each model in the short-term operation of cascade hydropower stations. The result shows that the RF-SVR model has a higher fitting ability for the flow response relationship between hydropower stations, which can reduce the errors in the formulation of short-term dispatching plan, and effectively reduce the deviation of daily generation and the risk of water level violation. The research results can provide a reference for making short-term dispatching schemes of cascade power stations under complex hydraulic connections.

As a large number of water conservancy projects have been put into use in recent years, water conservancy departments have accumulated a large amount of information about reservoir scheduling regulations. This paper analyzed the existing reservoir scheduling regulations, and proposed a construction method of reservoir scheduling regulations knowledge graph based on DataG. In the design of the ontology model, the top-down method of disassembling the ontology twice was adopted on the reservoir scheduling mode. The differentiated knowledge extraction was performed on the structured and unstructured data. In the knowledge reasoning, the reasoning path of preconditions, scheduling measures and scheduling objectives were analyzed and defined. Finally, the visualization of the reservoir scheduling regulation knowledge graph was introduced for the Three Gorges Reservoir. The knowledge graph of reservoir scheduling regulation meets the needs of spatiotemporal dimension, solves the problem of multi-source heterogeneous data extraction, and realizes intelligent retrieval and recommendation in the field of reservoir operation.

In order to improve the search efficiency of the NSGA-Ⅱ algorithm, this paper introduced an arithmetic crossover operator with stronger global search ability and faster convergence speed to replace the simulated binary crossover operator used in the original NSGA-Ⅱ algorithm. Based on this, an improved NSGA-Ⅱ algorithm was proposed, the G_D index was used to evaluate the convergence capability of the multi-objective Pareto solution set. The method was applied to the research of Fenhe Reservoir water supply and ecological collaborative optimal scheduling to verify its effectiveness. By comparing the Pareto solution sets generated by different algorithms and various indicators of reservoir operation, and compared with the traditional algorithm, the number of iterations to reach the convergence state after the improved algorithm was reduced by 100 generations and the convergence time is shortened by 7.76%. The water shortage rate of each department under the condition of non-optimization was decreased, of which the effect of agricultural water shortage rate is the most significant, decreasing by 13.20% to 14.52%, and the total water supply increased by 0.268 to 0.303 million cubic meters. This paper verified the effectiveness of the improved algorithm and optimized scheduling, and provides an optional new idea for multi-objective optimal scheduling of reservoirs.

Xiangjiaba Hydropower Station has six functions: power generation, navigation, flood control, irrigation, reverse regulation, sediment retaining. Since the project was put into operation in 2012, all other benefits except irrigation have begun to show gradually. With the completion of the first water intaking tunnel project of the north and south main canal of Xiangjiaba, and the comprehensive construction of the first phase project of the north general irrigation area, the research on the impact of irrigation water intaking on the power generation of Xiangjiaba hydropower station is an urgent work. Based on the adjustment calculation of 43 years series runoff during 1970-2013, inflow variation of Xiangjiaba hydropower station was calculated by considering the impact of the six large reservoirs regulation and storage in the upstream and water diversion in the Yunnan province. On this basis, the impact of water intaking after the first phase of north irrigation area, north second phase of irrigation area, and irrigation district being completed on the power generation of the Xiangjiaba Hydropower Station was analyzed. The research shows that irrigation water intaking reduces the power generation of Xiangjiaba, which is 1.78×10⁸ kW·h, 2.84×10⁸ kW·h and 3.78×10⁸ kW·h, respectively, compared with that before water intaking, and mainly in the dry season. After the intake of water in each period, the water discharge can be reduced by 109 m³/s at most, the annual average output can be reduced by 105 MW at most, and the number of installed hours can be reduced by 63 h at most.

In order to realize the sustainable utilization and maintain the healthy development of river and reservoir ecosystem, this paper applied energy value analysis to reservoir ecological operation for discussing the energy optimal operation of reservoir ecological service value. With the objective of maximizing the service energy of Manwan Reservoir and the constraints of ecological water demand and social economic water consumption, an optimal operation model of reservoir ecosystem service energy was established, and the ant colony algorithm was used to solve the model. The results show that the total service energy of Manwan Reservoir is 2.10×10²² sej in high flow year, 1.79×10²² sej in normal year, 1.58×10²² sej in dry year. Main service values are ecological regulation, water supply and ecological support, material production followed, cultural entertainment is the minimum. The results have practical value and important significance for maintaining the healthy development of the Lancang River basin, especially for the ecosystem of the Manwan Reservoir Region.

Taking the self- and cross-correlation of the multi-station streamflow series of the main and tributary of the basin as the starting point, a multi-site flood series simulation method based on the conditional resampling theory was proposed, and simulate the flood series of Pingshan, Cuntan and Yichang station on the main stream of Changjiang River. The simulation results were compared with the results of the multi-station seasonal autoregressive model (MSAR) for verification and analysis. The results show that compared with the traditional model, the proposed method can not only satisfy the basic statistical characteristics of the runoff series and the higher-order self- and cross-correlation structures of the series, but also further consider the historical extreme flood characteristic, and could generate multi-station simulated flood scenarios with different design frequency.

Ganjiang river trail channel is affected by both upstream water and the backwater effect of Poyang Lake during the flood season. The study of the water level changes has guiding significance for river flood control and shipping. Based on the measured data from 1990 to 2019 at the hydrological station in the Ganjiang river trail channel, this paper adopted the Mann-Kendall trend test and the Pettitt test to analyze the trend of the characteristic water level during the flood season (flood season and backwater of Poyang Lake season). The results show that the water level of the Ganjiang river trail channel had a significant downward trend. The interannual variation of the water level during the flood season was relatively uniform, while it showed a fluctuating shape during the backwater of Poyang Lake season. The mutation years were all around 2002. The main reason for the decline of the water level during the flood period is the erosion of the riverbed. The downward trend of the riverbed has slowed down significantly after 2013, so water level during the flood period stabilized after 2016. The water level during the backwater of Poyang Lake season is mainly affected by the erosion of the riverbed, and the change of the downstream water level will also have a certain impact.

In recent years, urban rainstorm disasters have occurred frequently in China. The community, as an important component of the city, is exposed to urban flooding. In view of the imperfection of the waterlogging prevention and control system, this paper briefly analyzes the characteristics and prevention methods of urban flooding, and summarizes the limitations of the current system. A waterlogging prevention system based on micro system, minor system and major system is constructed from a drainage perspective. The waterlogging prevention and control methods based on site elevation, terrain slope, and water-retaining measure is established. A design method system including design points, design process, design diagram, and key design parameters is formed, which provides reference for the planning and design of sponge communities in new era.

As a special structure connecting core wall and foundation of asphalt concrete rockfill dam, its stress state is very important to the stability of the dam. Taking the asphalt concrete core rockfill dam of Chongqing Miaotang under construction as an example, the maximum section of the dam was selected to establish a two-dimensional model for finite element calculation, and the stress distribution of the foundation under three different forms of unembedded bedrock, semi-embedded bedrock and fully embedded bedrock was discussed. The results show that there is a strong correlation between the embedment depth of the base in the bedrock and the tensile stress inside the base. During the period of water storage, the difference of tensile stress between different arrangement forms can reach up to 334%. Meanwhile, as the corridor was affected by the larger tensile stress inside the base during the period of water storage, it was easy to cause tensile damage. By changing the position of the corridor in the base, the tensile stress around the corridor can be reduced to avoid the damage of the corridor. After the location of the corridor is changed, the surrounding tensile stress can be reduced by up to 87% compared with the original.

The excavation of the foundation, the process of dam construction and the water level variation in foundation have significant effects on the displacement of the foundation and structure of a sluice dam on deep overburden. A finite element simulation method for the coupling of seepage and deformation during the whole process of the dam construction and operation was proposed to treat the foundation of a dam in Jinsha River. The results show that the foundation settlement caused by the dead weight of the filled concrete body of about 1 m height can be offset by 3 m height groundwater level rising in the foundation during the sluice construction. The change of groundwater level has a significant impact on the displacement increment of sluice dam during the construction period. The coupling simulation of seepage and deformation of the sluice dam in the whole construction and operation process was realized, which has supported the engineering design of the dam foundation treatment.

In order to study the surge wave characteristics of pumped storage power station with upstream and downstream surge chambers under small fluctuations, the mathematical model of small fluctuations in a pumped storage power station with this type of arrangement was derived based on the state-space method. The time-domain process of surge wave in the upstream and downstream surge chambers was solved by numerical simulation. The frequency-domain process of surge wave in the upstream and downstream surge chambers was obtained by the fast Fourier transform (FFT). Without considering the hydraulic coupling between the speed regulating system and the surge chamber system, the transfer function between the pressure pipeline flow and the water level of the surge chamber was established to obtain the amplitude-frequency characteristics of the surge chamber systems. The results show that the input signal frequency corresponding to the maximum amplitude of the surge wave in the upstream and downstream surge chambers is similar to the natural frequency of the surge chamber system, and the surge wave oscillation frequency in the surge chamber corresponds to the tail wave oscillation frequency of the unit speed. The surge wave characteristics of the surge chamber are closely related to the area of the surge chamber and the head loss coefficient of the water delivery tunnel. Increasing the area of two surge chambers can reduce the frequency and amplitude of surge wave in the upstream and downstream surge chambers, and enhance the stability of the system. The variation of head loss coefficient of the tunnel has no impact on the oscillation frequency of surge wave in the upstream and downstream surge chambers, but has a great impact on surge wave amplitude in the upstream and downstream surge chambers. The larger the head loss coefficient is, the smaller surge amplitude is, the system stability is better.

In view of the short water hammer control distance of a single air valve in long-distance and low lift water delivery projects, which can not effectively suppress the vacuum in the pipe, a new water hammer control scheme of combined protection of air-valve surge tank and air valve was proposed. Taking a practical project as an example, a comparative analysis of the hydraulic transient process was carried out for the air valve protection and the combined protection scheme of air-valve surge tank and air valve. The results show that the water column separation occurs in the main pipe when the air valve is used for protection, and a large impact water hammer is caused by the rapid exhaust. The combined protection scheme of air-valve surge tank and air valve can not only effectively suppress the vacuum in the main pipe, but also effectively alleviate the impact water hammer caused by exhaust. It is an economic and effective water hammer protection scheme, and can provide a reference for the water hammer protection of other long-distance and low-lift water delivery projects.

In order to alleviate the waste of resources caused by the leakage of urban water supply networks, taking predictive classification as the basic idea, the monitoring data after wavelet noise reduction processing was used in the prediction model of PSO seeking least squares support vector machine algorithm, and the prediction model was trained and evaluated, then combined with the model prediction error distribution law, the estimation method of threshold value and leakage volume was introduced for leakage detection. The results show that the average error between the model prediction and the actual water volume is low, the stability is high, and the combination of the prediction-threshold classification method can detect sudden leakage in a timely manner and estimate the leakage volume relatively accurately.

Aiming at the leakage problem of urban water supply network, the traditional leakage location model is solved by single objective optimization method. Its objective function is composed of the weighted sum of optimization objectives. Improper value of weight factor will degrade the model positioning result. This paper proposed a multi-objective optimization model for leakage location of water supply network based on NSGA-Ⅱ. In this model, the number of leakage point and diffuser coefficient were taken as decision variables, and the minimum error between the actual monitoring value and the simulation value of pressure and flow monitoring point was taken as the optimization objective, and NSGA-Ⅱ algorithm was used to find the optimal solution. In order to verify the effectiveness of the model, it was applied to the actual water supply network in a residential area. Considering the common fault conditions in the actual operation of the pipe network, the leakage accidents of single node and two nodes were respectively simulated and located. Compared with the two widely used leak location models, the results show that the multi-objective optimization model based on NSGA-Ⅱ can accurately and stably locate the nearby area where the actual leak occurs.

When the diffusion angle of each side of the wing wall in the gate is 12°, the horizontal distribution of outlet velocity of single-stage stilling basin is easy to be uneven in the medium and low water level period. To solve this problem, based on the physical model test, the law of horizontal distribution of outlet velocity of two-stage stilling basin was studied. The results show that with the decrease of downstream water level, the outlet velocity at the left and right banks of the second stage stilling basin changes in four stages: decrease- increase-decrease-increase, and the initial water level and water level range of each stage were closely related to the Fr. The smaller the incoming flow Fr is, the stronger the horizontal diffusion ability of hydraulic jump in the second stage stilling basin is, and it will be less disturbed by the backflow on both sides of the first stage stilling basin. The range of water level in the second stage will be larger, and it is more suitable for the medium and low water levels. The closer the downstream water level is to the end water level of the second stage, the greater the outlet velocity at both sides of the second stage stilling basin is, and the horizontal distribution of outlet velocity is more uniform. When the incoming flow Fr is the same, the regulating effect of the second stage stilling basin is more significant at low water level, and the energy dissipation rate is greater. The results can be used as a reference for the design of energy dissipation facilities under the gate and the operation management of the gate.

In view of the problem that the current 180° turning pool of the fishway has poor flow condition and affects the fish's upward tracing, the water flow condition was improved by extending the length of the upstream and downstream of the turning section and adding the staggered guide plate. Based on the study of a certain vertical slot fishway, numerical simulation was used to research on the distribution of flow regime, velocity, turbulent kinetic energy and turbulent dissipation rate of four turning pool structures. The results indicate that extending the length of the upstream and downstream of the turning section and adding the staggered guide plate can effectively guide the mainstream to center, maintain the stability of the mainstream and avoid the formation of a large-scale recirculation zone, and it is beneficial to migratory fish. The results of this study can provide reference for the reconstruction and design of fishway.

The vertical slit fishway has the capacity to better cope with the fluctuation of water level in both upper and lower sections and favorable water flow conditions. Three schemes were designed for the shape of the fishway tank chamber of a certain project fishway. The physical models verified with a 1∶5 scales were used to investigate the impact of the tank chamber's structure on the flow pattern, maximum flow velocity, and hydraulic properties of mainstream region under different size and type of baffle and guide plates. This was done through numerical simulation calculation. They performed a test of the physical model on the optimal shape with scale of 1∶5. The physical model of the overall with scale 1∶20 was used to analyze the maximum velocity along the water depth and the vertical slit, and the diversion flow of the fishway under different water depth conditions was proposed, providing reference and reference for similar projects.

The structure of fishway is the major factor that fish migrates successfully. The impact of pier head structure and horizontal interval of baffles on the hydraulic characteristics of a vertical slot fishway pool were researched. Twelve different working conditions were composed of two factors, namely, the diversion angle of pier head and the relative position of baffles. The RNG κ-ε turbulence model was used to simulate the hydraulic characteristics of fishway. The results indicate that the influence of pier head structure on hydraulic characteristics is mainly reflected on velocity and turbulent energy, and the smaller the diversion Angle, the smaller the velocity and turbulent energy are. The distance between flow deflector and baffler plate changed the mainstream flow pattern and area size, and then affected the distribution of flow velocity. When the relative position of b₀/L=0.15 or so, the flow pattern in the pool was reasonable, which met the basic requirements of fish migration.

To accurately evaluate the comprehensive utility tunnel under river shield tunnel construction safety, reduce the safety accidents in the construction process, based on the method of risk breakdown structure (RBS), risk evaluation index system of four first-level indicators was constructed including engineering geological risk and comprehensive utility tunnel itself risk, environment risk, construction risk management. Based on the linear combination of interval number analytic hierarchy process (AHP) and indicator correlation method (CRITIC), the comprehensive weight was determined. Based on matter element theory, the weighted average relation degree was calculated to determine the final evaluation result. This method was applied to the comprehensive pipe corridor project of Yueyang Avenue sewage treatment at the Wangjia River section. Monte Carlo method was used to analyze the sensitivity of 15 basic indexes based on matter-element theory. The research results show that the construction project of Yueyang Avenue sewage treatment comprehensive pipe corridor at Wangjia River section is medium-risk, which is consistent with the actual situation. The sensitivity analysis shows that the surrounding rock strength and the buried depth of tunnel are more sensitive. The research results can provide a basis for the safety control decision and measure making of the project.

Affected by the construction progress and other objective factors, the rock anchor beam may undergo loading with incomplete support, which seriously threatens the structural stability. In this paper, the rock anchored beam of a large hydropower station was taken as the research object. The three-dimensional nonlinear finite element simulation method was used to simulate the excavation of the main powerhouse and the filling of the rock anchored beam according to the actual excavation sequence. The continuous medium cementation element was introduced to simulate the weak contact between the beam concrete and the rock mass wall seat. The simulation results show that the load condition has a little impact on the stress and deformation of surrounding rocks, the initial support structure, and the rock anchor beam. The cementation surface between the surrounding rock and the rock anchor beam has a tendency to open, but it does not behavior obvious opening. The monitoring data such as the stress of the rock anchor beam and the deformation of the joint between the anchor beam and the rock wall remain basically unchanged, and no abnormal data are found, proving that the working state of the anchor beam is normal.

In view of the current problems such as less research on the combined support of anchor cable and frame lattice beam in slope reinforcement, the actual project of slope support on the left bank of a hydropower station was taken as the background. The stability of the original slope was analyzed by combining the limit equilibrium method and the finite element strength reduction method. The combined support scheme of anchor cables and frame lattice beams was studied. It mainly included anchor cable anchoring force calculation, anchor cable arrangement spacing, anchor cable length, optimal incidence anchoring angle and frame lattice beam size, etc. Finally, the support effect was studied by combining with numerical simulation. The results show that the original slope needs to be reinforced and supported. The error of the original slope safety coefficient obtained by the finite element strength reduction method is less than 1.5%-2.0% with the limit equilibrium method. The temperature loading method was used to simulate anchor cable prestressing for stability analysis of slope with combined support of anchor cable and frame lattice beams, and the combined support is effective and no obvious slip crack surface appears after the support. The study can provide reference for similar slope support projects.

In order to study the degradation of mica-quartz schist under the action of dry-wet cycles, which widely distributed in Shiyan, Hubei province was taken as the research object. The hydroscopicity test, wave velocity test and scanning electron microscope test were carried out on the samples under the action of dry-wet cycles, respectively, to reveal the law and mechanism of physical deterioration. The test results show that the water absorption increases greatly, the wave velocity decreases and gradually tends to be stable with the increase of the number of dry-wet cycles. Besides, the surface of the sample was gradually disseminated into reddish-brown, and the foliation was gradually cracked and connected. Finally, the flake particles became more, round and granulated, the number of cracks increased and the micro-fractures gradually expanded, so the water absorption rate increased and wave speed decreased of mica-quartz schist under the action of dry-wet cycles.

Since the mechanical properties of dam materials can directly affect the settlement deformation and structural stability of core wall DAMS, it is necessary to explore the mechanical properties of soil-rock mixture and the internal deformation and failure mechanism by means of macro and micro in order. Taking the Rumei Hydropower Station in Tibet in Lancang River as research background, particle flow code (PFC) method based on discrete element was used to carry out large-scale triaxial numerical simulation test. The results show that with irregular enhancement in the form of block stone, the stress peak nodes was in advance, peak strength increased obviously with significant softening characteristics, shear shrinkage was not obvious, and the dilatancy is prominent; The shear zone evolved from a single “工” shape to a complex “工” shape. The thickness increases from 45 mm to 105 mm, and the final swelling failure area increases exponentially to 35 000 mm². The extreme value and the number of force chain strength increased. Increasing the stone content was the key to improve the peak strength of the sample. When the rock content was low, the shear shrinkage characteristic was prominent, and the dilatancy characteristic was not obvious. With the increase of the stone content, the “gear” effect of the block stone was enhanced, and the shear zone failure mode was transitioned from smooth reverse “S” shape to multiple irregular shear zones, with the thickness increasing from 47.5 mm to 105 mm, the swelling failure area evolving from 12 800 to 35 000 mm², and the number of strong chains increased. The extreme strength of the force chain was increased from 10.49 kN to 164.30 kN. In conclusion, it is suggested to select blocks with high irregularity and increase the stone content to enhance the structural strength stability. The research can provide reference for the stability evaluation of the project in the later stage and the work of the proposed dam.

The study of the effect of water vapour on soil heat and moisture migration patterns at different heat source temperatures is of great significance for the application of soil heat storage and ground source heat pump technology. In this paper, a numerical model of one-dimensional unsaturated soil water-vapour-thermal coupling migration was constructed by Hydrus-1D software, and the numerical simulation study of sandy soils with and without water vapour migration at different heat source temperatures was carried out. The results show that for soil heat migration, taking into account water vapour migration increases the radius of influence of the heat source from 60 cm to 78 cm, an increase of 30%; For soil moisture migration, the radius of influence of the heat source increases from 78 cm to 100 cm, an increase of 28.21%. Compared with not considering water vapor migration, considering water vapor migration can reduce the temperature loss during soil heat storage, and the decrease of temperature loss increases with the increase of heat source temperature. When the temperature of the heat source is above 70 ℃, the temperature and moisture fields of the soil change unsteadily and dryness may occur in the vicinity of the heat source.

In order to study the influence of loading rate on the damage evolution of hydraulic concrete, notched cubic specimens with side lengths of 300 mm and 450 mm were tested by wedge splitting test with different loading rates of 0.1 mm/s, 0.01 mm/s, 0.001 mm/s. Acoustic emission technology was used to monitor the acoustic emission signals of concrete in the damage process. Test results show that the variation of AE event rate during failure process of concrete can be divided into quiet, active, and attenuation period, among these the active period increases with the decrease of loading rate. The damage was defined according to the AE events, and it is found that the damage process of hydraulic concrete can be divided into three stages: crack initiation, acceleration and failure. The smaller the loading rate is, the faster the growth rate of the acceleration stage is. The damage evolution model based on the AE event obeys Weibull distribution, which can better reflect the influence of loading rates on the damage evolution of hydraulic concrete.

In order to study the damage behavior of fiber reinforced concrete at high temperature, the acoustic characteristics of hybrid fiber reinforced concrete (PVA fiber and basalt fiber) at different temperatures were tested, and the mechanism was explained from the microscopic level by combining the results of the SEM. The results show that with the rising of temperature, the degree of ultrasonic waveform distortion is more significant, and the attenuation of waveform amplitude is gradually intensified; The incorporation of fiber or the increase of temperature will reduce the amplitude of the dominant frequency of the waveform and increase the energy dissipation caused by the ultrasonic penetration of the specimen. At high temperature, after PVA fiber is melted, a large number of pores remain and gradually form connecting pores, which promote the release of pore steam pressure and alleviate high-temperature damage, while basalt fiber continues to play a bridging effect to inhibit the continuous development of high-temperature cracks.

Pump device is the core of pump station, it is very important to carry out optimization research of pump unit. Taking the uniformity of axial velocity and the weighted average angle of velocity as optimization objectives, the hydraulic performance of inlet and outlet channels of a large vertical axial flow pump under pump mode and reverse power generation mode was optimized under all working conditions. Through the multi-scheme modeling of the inlet and outlet flow channels of the vertical axial flow pump device, the size of each section and the outer inverted line of the elbow section of the inlet and outlet flow channels were changed without changing the initial surface and the shape of the outlet section. The numerical simulation results of different inlet and outlet flow channels were compared. The distribution uniformity of flow velocity at inlet and outlet section of impeller, the average angle of weighted velocity, the hydraulic loss at inlet and outlet channel, and the variation rule of external characteristics and performance of axial flow pump device were analyzed in detail under pump mode and reverse power generation mode. The research results show that the hydraulic design of the flow channel under pump condition and reverse power generation condition can be considered comprehensively to improve the hydraulic performance of the pump unit under various operating modes in the design stage of the pump device for pump station. The research results provide theoretical support and engineering practice reference for hydraulic design and optimization of pump device in pump station.

In order to qualitatively and quantitatively grasp the influence of the installation elevation of horizontal water stops at transverse joints on the structural stress of the bulb tubular power house, taking a certain engineering project as an example, a three-dimensional finite element model of the powerhouse was established to analyze the stress of the structure on the condition of the horizontal water stops changing within a certain range. The results show that the installation height of horizontal waterstops has a significant impact on the stress of structure, and an appropriate installation height of horizontal waterstops can improve stress of structure. Taking into account various factors, the optimal horizontal water stop installation height is 70% of the installable height, which can provide a reference for the design of the transverse joint water stop of the bulb tubular power house.

Due to the long-term operation in the low-load area, the hydropower unit deviates from the optimal operation area, resulting in large vibration of the unit, poor flow state of water flow, and other adverse consequences, such as cracks in runner blades and serious cavitation of the unit. In view of the complex flow conditions in the draft tube, this paper proposes two improvement schemes. Based on RANS equation, the standard SST κ-ω turbulence model is adopted to calculate the steady and unsteady solutions for three operating conditions of 0.45P_r(P_r is rated output), 0.60P_r, and 0.75P_r. The results show that the installation of the guiding device can effectively reduce the eccentric vortex band of the draft tube, and greatly reduce the pressure pulsation amplitude, so as to reduce the vibration of the unit. Considering the streamline of draft tube, vortex zone of draft pipe, turbine efficiency and pressure pulsation amplitude, especially the importance of pressure pulsation intensity to the stable operation of the turbine, it is concluded that the symmetrical arrangement of two diversion plates at the inlet of the draft tube has the better improvement effect on the Francis turbine. The results provide a certain theoretical basis for the safe operation of the hydraulic turbine unit under low load.

At present, in the region of China Southern Power Grid, there is a case that the actual load adjustment amount of primary frequency control of some hydropower units cannot reach the theoretical value under certain working conditions, resulting in the assessment of primary frequency regulation. This paper processed the original operation data of a unit, and calculated the actual load adjustment amount and actual adjustment rate of primary frequency regulation. Compared with the theoretical value, the qualified working condition area of the primary frequency regulation process was found out. The characteristic operating points were selected in the qualified working condition area, and the multi-objective particle swarm optimization algorithm based on Pareto optimization criterion was used to find the optimal PID parameters. The simulation results show that the optimized PID parameters can make the unit have better primary frequency regulation performance index than the actual parameters of the governor.

The performance of thrust bearing is very important to the energy conversion efficiency and stable operation of hydro-generator unit. Therefore, the thrust bearing of a hydropower station was taken as the research object. The characteristics of thrust bearing oil film under different rotating speed conditions were studied. The pressure, speed and temperature distribution inside the oil film were analyzed. The influence law of rotating speed on the performance of thrust bearing was clarified. The results show that the rotational speed cannot change the pressure distribution on the thrust pad surface, but with the increase of rotational speed, the relationship between the maximum pressure and rotational speed is almost linear; The high temperature zone on the thrust pad surface moves away from the main shaft towards the oil outlet side with the increase of the rotating speed, and the average temperature difference and the maximum temperature difference show an upward trend. At runaway speed, the thrust bearing needs to bear much higher pressure than the rated speed, and also needs to bear local high temperature. The maximum temperature difference at runaway speed is more than 40 K, which is easy to cause bearing bush burning. The research results provide theoretical support for the operation and optimal design of thrust bearings in hydropower stations.

In view of the problem of inconsistency and lack of real-time synchronization of data in each security zone with the increase of specialty system, this paper analyzed the cross-regional synchronization requirements of the Yalong River integrated hydropower management and control platform system, and proposed a simple, stable and reliable cross-regional synchronization system architecture based on the characteristics of unified construction and deployment of all specialty system based on the integrated platform. Real-time synchronization was achieved by intercepting the write operation context through the platform service gateway. The design realized the unified communication management and synchronization optimization of the professional data of the Yalong River integrated control platform system, effectively improved the performance and reliability of the system, and adapted to the future development of integrated system business of water, electric power and new energy dispatch.

Long distance and concealment of underground cable in hydropower station result in difficulties in cable fault location. Due to the simple wiring, the impulse high-voltage flashover method is commonly used to locate cable faults, which needs technicians with rich waveform analysis experience to locate fault accurately. For the above situation, by studying the fault positioning principle and waveform analysis method of impact high voltage flashover, a cable fault location technology based on traveling wave cross-correlation method was proposed. The simulation analysis results show that the proposed method can effectively realize automatic cable fault location. Finally, the analysis steps and procedures of power cable fault location has been practiced in Houziyan Power Generation in Dadu River and realized high-precision positioning of 10 kV cable fault point, which reduced the cable fault locating workload and working hours while improving the efficiency of cable fault location.

At present, the existing speed relays on the market only collect single signal source, poor anti-interference. It is easy to disorder the signal of the speed node output caused by measurement signal distortion and measuring channel fault. In order to improve the reliability and accuracy of the speed relay, two channels of residual voltage signals and two channels of sprocket speed measurement signals were respectively connected. Then the dual-probe tooth sequential speed measurement method was combined with the logic of selecting one out of three speed signals. The judgment method selected one speed signal as the main signal. In the signal output process of the rotational speed node, the limiting average filtering method and the method of retrieval interference output blocking were applied to eliminate the distortion in the signal output process. Through the simulation test bench test and the application in the actual generator set, the anti-interference ability of the acquisition signal loop, the signal measurement accuracy, and the reliability of the output action of the speed node have been significantly improved.