Aquatic ecosystem is an important carbon pool of terrestrial ecosystem， among which peatland is the ecosystem with the highest carbon accumulation in freshwater wetland， storing nearly one-third of the carbon in the global soil carbon pool. As such， under the background of climate warming， the balance of carbon pool in peatland will have a huge change， which will affect the global carbon emissions budget. This paper summarizes and comments on the formation， evolution and carbon accumulation process of peatland in the historical period， the potential carbon emission process mechanism and influencing factors of peatland under the background of climate change at the present stage， and the use of model to predict the dynamic change of peatland carbon pool in the future. The results show that the carbon accumulation of peatland has been rapid since the Holocene， but the carbon storage of peatland has changed significantly due to the influence of global warming. The rising temperature， the change of temporal and spatial distribution pattern of precipitation and the change of environmental vegetation caused by climate change have affected the biogeochemical process driven by microorganisms in peatland， thus affecting the carbon dynamics of peatland， but the dominant factors and interactions require further research. At the same time， as an important way to predict the future carbon dynamics of peatland， models’ prediction results have great uncertainty due to their different parameters and structures. Therefore， how to obtain more measured data， optimize the model structure and improve the accuracy of the results will be urgent problems to be solved in the future. This paper is helpful to explore the impact of climate warming on the carbon cycle of peatland， to estimate the carbon emissions of peatland system in the future， and to provide an important theoretical basis for achieving the goals of “carbon peak” and “carbon neutralization”.

With the development of industrialization and urbanization， the pollution of rivers and lakes is becoming increasingly serious. Reasonable evaluation of the ecological health of rivers and lakes is the basic premise for the restoration of rivers and lakes. Therefore， a study of evaluation system of river and lake ecological health for Tianmen Han Diversion Irrigation District has been carried out， by taking Hanbei River and Bantou Lake as examples. Firstly， the evaluation index system of river and lake ecological health is established， which is composed of 22 indices from five aspects： physical morphology structure， hydrological characteristics， water quality， aquatic organisms and benthos. The classification standard of each index is determined according to five grades： health， near health， sub-health， slightly morbid and morbid. Finally， the evaluation model is established by using analytic hierarchy process and entropy weight method to evaluate the ecological health of the typical river and lake in the Han Diversion Irrigation District. The results show that the water quality， hydrological characteristics， aquatic organisms and benthos of Hanbei River are at the “near healthy” level， and the overall ecological health is good， except that the physical structure of the river is “sub-healthy”. The indicators of Bantou Lake are basically “slightly morbid” or “sub-healthy”， and the overall ecological health is poor. The evaluation results objectively reflect the actual water ecological status of Hanbei River and Bantou Lake in the Han Diversion Irrigation District， and provide a scientific basis for the environmental management and ecological restoration of rivers and lakes in the irrigation area.

A storm water management model （SWMM） is conducted on the basis of model calibration and validation with synchronized monitoring data of rainfall， runoff water quantity and quality in Tianhe Wisdom City. The SWMM model is applied to simulate LID in natural， semi-saturation and saturation conditions of runoff control and contaminant reduction in different rainfall return periods. The results indicate that the runoff control rate of all LID conditions decrease with rainfall return period increasing， the highest runoff control rate is natural LID condition， saturation LID condition shows not significant variation in different rainfall return periods. Compared with natural LID condition， the rate of runoff peak discharge and contaminant control decrease in semi-saturation and saturation LID condition. The investigation of different initial LID conditions can provide guidance for the LID planning， designing and operation management.

When the factors affecting the spatial and temporal variation of nitrogen and phosphorus in rivers of karst watershed are considered， the unique karst geomorphic and its accompanying land use features of underlying surface cannot be ignored. To reveal the effects of karst feature and land use types on nitrogen and phosphorus of the Huixian karst wetland rivers， water samples from Mudong River， Huixian River and Xiangsi River were collected monthly for nitrogen and phosphorus analysis from October 2017 to September 2021. Based on the statistical analysis of river N and P concentration in catchments ranging from 21.79 to 376.42 km²， in combination with Pearson and Grey correlation analysis， the relationship between N， P concentrationof rivers and the area proportion of landuse type， karst landform， as well as the hydrometeorology factors was studied. The results showed that ① During the monitoring period， total nitrogen （TN） pollution was more serious than total phosphorus （TP） pollution. The concentrations of TN and TP varied from 0.30 to 27.55 mg/L and 0.03 to 2.49 mg/L， respectively， with 70.3% of 518 samples had TN > 1.0 mg/L and 35.1% had TP>0.2 mg/L. Under the influence of hydrometeorology， the peak concentrations of TN and TP appeared in the dry season， and the mean concentrations decreased in the wet season. ② The nitrogen and phosphorus in rivers mainly came from agricultural land （include paddy field， dry land， and orchard） which was significantly affected by human activities. Wetland and ponds contribute to nitrogen and phosphorus reduction. The covered karst area has a positive effect on nitrogen and phosphorus emission levels. ③ The correlation between the concentrations of phosphorus （TP and TDP） and precipitation is stronger than that of nitrogen （NH₄ ⁺-N， NO₃ ^-N and TN）， especially in the wet season. This research helps to improve the knowledge about the status and main influence factors of N and P pollution in Huixian karst wetland rivers. It is important to pay attention to nitrogen and phosphorus in karst wetland system for water quality safety and management.

In order to study the infiltration and purification effects of different types of permeable pavement on runoff and rainwater， this paper designs three permeable concrete pavement systems （PCPS） with different structures by using recycled aggregate of construction waste， namely recycled brick aggregate permeable concrete pavement system （PCPS1）， recycled concrete aggregate permeable concrete pavement system （PCPS2） and ordinary permeable concrete pavement system （PCPS0）. The rainwater infiltration capacity and the purification capacity of typical pollutant SS， COD， TP and TN are tested under different rainfall return periods and pollutant concentrations. The results show that the infiltration and purification capacity of PCPS decreases with the increase in rainfall return period and pollutant concentration； the PCPS1 has the best purification capacity of pollutant SS， COD and TN， the maximum purification rates are 98.95%， 56.31% and 34.11% respectively，and the PCPS2 has the best infiltration capacity and purification capacity of pollutant TP，the maximum purification rate is 76.50%. Recycled aggregate PCPS has high internal porosity， and the attachments carried on the surface have adsorption function， which has good infiltration capacity and purification effect on runoff and rainwater， which provides a good way for the reuse of construction waste in the future.

Urban lakes are important surface water resources， which are of great significance for regulating runoff and maintaining ecological environment.Through the construction of water diversion project， the pollution of urban lakes can be effectively alleviated by improving the hydrodynamic and water quality conditions. In this paper， Balihu， an urban lake with serious water pollution in Jiujiang City， is taken as the research object. Aiming at the water pollution problem of urban lakes， the water quality status and main pollution sources of Balihu are found out through field water quality detection. The two-dimensional hydrodynamic water quality model of Balihu Lake based on DEM is established， and the parameters are calibrated and verified. Finally， based on the model， the improvement effect of the diversion project is analyzed， and the optimal diversion flow of Balihu is determined by using the cost and benefit evaluation method. The results show that the optimal diversion flow of Balihu is 70 m3/s. The corresponding working condition is working condition 4 （Xinkai River diversion 50 m3/s， Saicheng Lake diversion 20 m3/s）. The net benefit is 589 800 yuan/time when it runs for 8 days.

The adverse effects of climate change and urbanization on extreme rainfall and urban environment have brought great pressure to urban drainage infrastructure and seriously threatened the water security and environment in urban areas. The urban drainage system， which collects and transports rainwater and sewage， is an important infrastructure to ensure urban water safety and water environment. The comprehensive reduction of inundation risk and black and odorous water cannot be separated from the reasonably integrated operation of urban drainage pipe network， wastewater treatment plant and river. This paper reviews the research progress of integrated modeling and operation of plant， network and river， demonstrates the necessity of integrated operation of plants， networks and rivers， and puts forward the key points of future research on the current technical problems.

The implementation of river （Lake） shoreline demarcation is not only an important content of implementing the reform of ecological civilization system in China， but also an important guarantee for the full implementation of the river （lake） leader system. Due to the unclear boundary of most river and lake management boundaries， some river and lake management and protection boundaries have been arbitrarily occupied， which interferes with the normal water management order and destroys the river and lake ecological environment. By studying the relevant documents such as national and local rules and regulations， analyzing the ideas of other provinces to determine the demarcation standards， and based on the situation of Jiangxi Province， this paper puts forward the river and lake demarcation standards.The river and lake demarcation standards in Jiangxi Province are determined separately according to whether there is a dike or not. With reference to the management regulations and standard requirements， rivers and lakes with embankments are divided into three grades： Grade 1~2， grade 3~4 and grade 5 according to the dike grade. Rivers and lakes without embankments are mainly determined according to the historical highest flood level or design flood level.The determination of river and lake demarcation standards lays a working foundation for river and lake demarcation in the province， and also has a reference value for river and lake demarcation in China.

As an ecological ecotone between land and water area， nitrification-denitrification is two important processes of nitrogen cycle in riparian zone. The potential and influencing factors of nitrification and denitrification in riparian zone during flooding period and dry period are explored. It provides a certain scientific basis for nitrogen pollution control of water body. In this study， the riparian zone of Xia jiasi was selected as the research object， the soil samples of riparian zone were collected in flooding period and dry period respectively， and the nitrification and denitrification intensity of riparian zone in dry and wet environment were measured by indoor culture experiment. The results show that： ① the maximum content of EC， pH， SOC， \mathrm{N} {{\mathrm{H}}_{\mathrm{4}}}^{+} - \mathrm{N}、 \mathrm{N} {{\mathrm{O}}_{\mathrm{3}}}^{-} - \mathrm{N} and TN appear in surface soil no matter during the flooding period or during the drying period. ② the maximum nitrification rate and nitrification activity of all layers of soil in riparian zone during flooding period were （1.81，0.44，0.83） mg/（kg·d）， （86.18，22.38，40.38）%. The maximum nitrification rate and nitrification activity of each layer during the drying period were （3.00，2.05，0.48） mg/（kg·d）， （138.97， 96.92，24.45）%. The maximum nitrification potential of the riparian zone appeared in the topsoil， and the average nitrification potential in the dry period was higher than that in the flooding period. ③ the denitrification rate decreased with the increase of soil depth， and the denitrification rate of topsoil reached the maximum， which was （69.98，63.91） mg/（kg·d）， respectively. The average denitrification rate of riparian zone in dry period ［24.23 mg/（kg·d）］ was higher than that in flooding period ［24.02 mg/（kg·d）］. The denitrification activity in flooding period reached the maximum value of 99.07% in 10 days after culture， and it reached up to 101.91% in 6 days after culture in dry period. ④ the differences in nitrification potential and denitrification potential in flooding and dry period were related to soil environmental factors. The nitrification potential in flooded period was positively correlated with SOC， \mathrm{N} {{\mathrm{H}}_{\mathrm{4}}}^{+} - \mathrm{N} and pH content， and nitrification potential in dry period was positively correlated with TN. There was a significant positive correlation between denitrification potential and SOC， \mathrm{N} {{\mathrm{H}}_{\mathrm{4}}}^{+} - \mathrm{N} content in dry period. It was found that carbon source and nitrogen were the main factors affecting nitrification and denitrification potential in riparian zone.

The common comprehensive water quality models have high requirements for hydrological data and water quality data， and a large amount of measured water-quality data is needed to set initial conditions and boundary conditions during simulation. In addition， their index system is inconsistent with the water quality indicator required by China’s actual management. Practical application of these models is difficult. In order to solve the problem of inconsistency between the commonly used comprehensive water-quality model index system and water quality index required by China’s actual management， and to improve its practicability and usability， focusing on the growth and metabolism of chlorophyll-a and the balance of dissolved oxygen， and comprehensively considering the interaction of five water quality components including total phosphorus， ammonia nitrogen， permanganate index and so on， a 5X comprehensive water-quality model which is suitable for water environment management requirement in China is built. This model is systematically reconstructed and generalized on the basis of QUAL-II model to reduce the data demand for initial conditions. At the same time， the comprehensive water-quality model is coupled with a two-dimensional hydrodynamic model under the DEM grid. The coupled model conforms to the geographic information system standard and has strong portability. In this paper， the finite volume method is used to discretize the model equations， and the SIMPLEC algorithm is used to solve the flow field. Finally， the tridiagonal matrix algorithm （TDMA） and the alternate direction implicit method （ADI） are used to solve the discrete equations to get numerical solution results. Taking Bali Lake in Jiujiang City as the research object， this model is calibrated and validated. The PBIAS （percentage deviation） method is used to judge the performance of hydrodynamic and water-quality simulation. The results show that the hydrodynamic simulation PBIAS value of this model is 0.95%， which has excellent simulation effect. The simulation performance of several water-quality components such as dissolved oxygen， permanganate index and total phosphorous is excellent. The simulation effect of ammonia nitrogen is good， and the simulation effect of other water-quality indicators is satisfactory. In general， the model meets the actual requirements of China’s water environment management. Its mechanism is clear and it has strong usability and the value of further development. It is applied to the comprehensive simulator of the urban water cycle and water environment with the characteristics of “mountain-city-stream-lake-river” in Jiujiang City and good results have been achieved. It has a guiding significance for the realization of ecological civilization construction and the Yangtze River conservation strategy.

In order to explore the flow characteristics of open channels with composite submerged vegetation， round wooden sticks are used to simulate rigid vegetation and plastic model grasses are used to simulate flexible vegetation. Based on the laboratory flume， water flow experiments under two layout patterns of rigid-flexible and flexible-rigid are carried out. The velocity distribution along the route， the vertical velocity distribution， the water level along the route and the relative turbulence intensity changes in the vertical direction are discussed. The results show that the flow velocity along the way fluctuates gently in the rigid area under the two patterns， and the change is greater in the flexible area， with the maximum value basically appearing at the end of the flexible area. The vertical velocity distribution in the vegetation area is basically an “S” or “C” distribution. The fluctuation of flexible vegetation is greater than that of rigid vegetation. The water level changes along the way are basically the same in the two patterns， and the water level is high under the influence of water blocking inside the vegetation. The vertical relative turbulence intensity distribution trend under the two patterns is also similar， the turbulence intensity from the bottom to the water surface increases first， then decreases and then increases. The relative turbulence intensity is the largest in the top layer of the plant.

Based on the daily precipitation data of 622 stations， the change and trend predictions of extreme precipitation events in China are explored by using the Mann-Kendall test， Sen’s slope， R/S analysis and other methods. The results show that： ① Over the past 60 years， the extreme precipitation index in China has shown a no significant increase （p>0.05）， and the maximum day precipitation （RX1day）， the maximum five-day precipitation （RX5day）， the heavy precipitation （R95p） and the total precipitation （PRCPTOT） have increased by 0.52， 0.10， 0.64 and 6.00 mm/10 a， respectively. The extreme precipitation intensity index （SDII） increased significantly at a rate of 0.13 （mm/d）/10 a （p<0.05）， while the extreme precipitation day index shows no significant increase （p>0.05）， with R20 and R50 increasing at rates of 0.13 and 0.06 d/10 a， respectively. ② From the perspective of different regions， in addition to continuous wet days （CWD）， other indices of extreme precipitation events show a significant increase in Southern， Central， Northwest and Southwest China （p<0.05）， and a significant decrease in Northeast and Northern China （p<0.05）. Thereinto， the increase rates of RX1day are 0.62， 0.52， 0.21 and 0.49 mm/10 a in Southern， Central， Northwest and Southwest China， respectively. The decrease rates of RX1day are -0.48 and -0.63 mm/10 a in Northeast and Northern China， respectively. Outside of Southern China， CWD decreases significantly at rates below 0.05 d/10 a （p<0.05）. ③ In addition to R95p and PRCPTOT， other extreme precipitation indexes will continue their historical trend in the future （H>0.5）. Both the extreme precipitation index and the extreme precipitation intensity index will show a sustained growth trend， and the significant increase will continue in Southern， Central， Northwest and Southwest China. Although the extreme precipitation daily index is generally an upward trend， the CWD will still show a strong downward outside southern China. The results can provide a reference for rainstorm disaster warnings and regional water resource utilization in China.

The multi-step forecast accuracy of daily runoff time series is improved. Based on the wavelet packet decomposition （WPD） method， the elephant group optimization （EHO） algorithm and the extreme learning machine （ELM） and deep extreme learning machine （DELM） two predictors， the WPD-EHO-ELM， WPD-EHO-DELM daily runoff time series mixed forecast model， and applied to the multi-step forecast of daily runoff time series at Jingdong Hydrological Station in Yunnan Province. Firstly， the two-layer WPD is used to decompose the daily runoff time series data into 4 sub-sequence components to reduce the complexity and instability of the daily runoff series data. Secondly， when the delay time is 1， the Cao method is used to determine each sub-sequence component. Finally， this paper introduces the principle of EHO algorithm， uses EHO to optimize ELM， DELM input layer weights and hidden layer biases， and establishes WPD-EHO-ELM and WPD-EHO-DELM models to perform multi-step prediction of each sub-sequence component. And the prediction results are added and reconstructed to obtain the final multi-step forecast results of daily runoff. And the WD-EHO-ELM and WD-EHO-DELM models are constructed based on the wavelet （WD） decomposition and the undecomposed EHO-ELM and EHO-DELM models as comparative analysis models. The results show that： ①WPD-EHO-ELM and WPD-EHO-DELM models have an average absolute percentage error of daily runoff forecast from 1d to 5 d for an example forecast period of ≤9.44%， pass rate ≥89.2%， and certainty coefficient ≥0.99， The accuracy grades are all Grade A， and the forecasting effects are better than other models such as WD-EHO-ELM. Among them， the forecast period is 1~3 d. The average absolute percentage error of daily runoff forecast is less than or equal to 1.81%， the pass rate is 100%， and the certainty coefficient is greater than or equal to 0.999 6. The forecast effect is the most ideal. ②WPD-EHO-ELM and WPD-EHO-DELM models can give full play to the advantages of WPD decomposition， EHO algorithm and ELM and DELM networks， and show high forecast accuracy and stability. The forecast accuracy increases with the number of days in the forecast period. ③Models and methods can provide a new approach for realizing the multi-step forecasts and precise forecasts of daily runoff time series.

Isotopes are adopted to label different water bodies to test and analyze the stable isotopes in the Hanbei River Basin. The transformation relationship and conversion ratio of atmospheric precipitation， rivers， soil water and groundwater bodies in the study area are explored to provide technical support for the sustainable management of water resources in the study area. The results show that the regional precipitation line is δD=8.44δ¹⁸O+7.88. Compared with the global precipitation line， the slope and intercept of the precipitation line in the Hanbei Basin are offset to a certain extent， and precipitation is obviously affected by evaporation. The results show that the proportion of atmospheric precipitation， soil water and groundwater in the river water of Hanbei Basin is 38.2%， 15.8% and 19.3%， respectively.

Reservoir operation is an important driver to river flow regime alteration. Aiming at the problem of separating the influence of single factors of reservoir operation on flow regime from the compound influence of multiple factors， this paper proposes a way to quantify the influence of the reservoir operation on flow regime alteration. The daily runoff of downstream section of reservoirs with the absence of the reservoir is simulated. Indicators of Hydrologic Alteration （IHA） and Range of Variability Approach （RVA） is used to quantify flow regime alteration under the two scenarios of the presence or absence of the reservoir during the assessment period compared with the near-natural period. The influence of the reservoir on flow regime can be quantified by comparing the flow regime alteration differences. The influence of the Xiaolangdi Reservoir on the flow regime of Huayuankou section and Lijin section is evaluated. Results show that： compared with the near-natural period， the flow regime in the Lower Yellow River is altered sharply， featured by the decrease and flattening of runoff. Under irrigation， flood control， water and sediment regulation and other operating tasks， the Xiaolangdi Reservoir ensures no drying up in the Lower Yellow River continuously， increases the monthly average flow in January and March to July， decreases the magnitude of annual maxima 1-day means and 3-day means， and increases the magnitude of annual maxima 1-day means， 3-day means， 7-day means， 30-day means and 90-day means， and decreases the number of highly-changed and medium-changed IHA. Compared with the near-natural period， the engineering conditions， water consumption and natural runoff of the Yellow River has changed significantly from 2000 to 2019， which jointly led to the flow regime alteration in the Lower Yellow River. Therefore， the influence of the Xiaolangdi reservoir operation on flow regime is not completely consistent with the measured flow regime alteration. The results of this paper reveal that when the IHA – RVA is used to study the impact of reservoir operation on flow regime， it is necessary to eliminate the impact of climate change， water use change and other factors， so as to ensure the accuracy of the results.

Exploring the extent to which the construction and operation of the reservoir changes the hydrological regime of the river will help to deepen the understanding of the ecological impact of the reservoir and provide directions for the optimal operation of the reservoir. In this study， the measured hydrological data of the inbound station and the outbound station of the reservoir are proposed as the comparison object， with the help of index of hydrologic alternation and the range of variability approach proposed by Richer et al. to assess the influence of reservoir operation on river hydrological regime. Compared with the common method of using the measured hydrological data at the downstream hydrological stations before and after the completion of the reservoir as the comparison object， the suggested method can effectively avoid the disadvantages of confusing upstream human activities with the impact of the reservoir and a lack of data. Two representative reservoirs on the main stream of the Yellow River， Longyangxia and Xiaolangdi， are selected to calculate the influence of reservoir operation on the hydrological regime of the river. By the comparison of the calculation results with the commonly used method， the reliability of the calculation method proposed in this paper is confirmed. The results show that the operation of Longyangxia Reservoir has a great impact on runoff， the comprehensive change degree is 0.71. The indicators with small changes are mostly indicative of high flow， such as the monthly average flow in the flood season， the occurrence date of the annual maximum daily flow， and the number of high pulse occurrences per year， etc. The operation of Xiaolangdi Reservoir has moderate impacts on runoff and sediment， the comprehensive change degrees are 0.43 and 0.35， respectively. The impact on runoff is mainly reflected in the average flow in August， the annual minimum daily flow and the date of occurrence of the annual minimum daily flow. The impact on sediment is mainly concentrated in sediment content in the flood season， high sediment content events and changes in sediment contents. The research results can provide a certain reference for the optimal operation of the two reservoirs. It also points out the importance of constructing a multi-objective optimization model to find a scheduling plan that takes into account both reservoir operation goals and river ecological protection.

Evapotranspiration （ET） is an important variable in the hydrological cycle and is becoming an alternative variable to replace the observed streamflow for parameter calibration in the hydrological models. In this study， the streamflow simulations produced by the SWAT （Soil and Water Assessment Tool）model based on two different calibration strategies， which use observed streamflow and ET as the calibration variable respectively， are compared to investigate the impact of parameter calibration based on ET on the streamflow simulation in the upper and middle part of the Xiang River Basin. Besides， the differences brought by the basin are analyzed. Multisource ET is used in the study， including the ET products from Moderate Resolution Imaging Spectroradiometer （MODIS） （named MOD16A2）， Global Land Amsterdam Model （GLEAM） and Global Land Assimilation Data System （GLDAS）. The results show that the SWAT model based on the parameter calibration using GLEAM， GLDAS and MOD16 can generate satisfactory streamflow simulation performances. For the calibration based on the three ET products， the NSE values of simulated streamflow are close to that calibrated based on the observed streamflow in the calibration period. In particular， the NSE values of the simulated streamflow are more than 0.50 at the Shuangpai Station and more than 0.70 at the Hengyang Station. Additionally， in the validation period， the NSE values of simulated streamflow obtained at the Shuangpai Station are more than 0.58， which are comparable to that calibrated based on the observed streamflow （0.60）. At Hengyang Station， the streamflow simulation performance generated from the parameter calibration based on ET is slightly better than that based on observed streamflow. It is worth mentioning that the SWAT model calibrated based on GLDAS and MOD16 can generate streamflow simulation with NSE of 0.72， which are significantly more than that calibrated based on the observed streamflow （NSE=0.6）. This study shows that remote sensing ET product has great potential for parameter calibration of hydrological models， and is more suitable for basins with larger areas. The strategy in this study can provide an insight into hydrological modeling in those ungauged regions.

As an important resource for human survival and social development， the carrying capacity of water resources plays an important role in enhancing regional strength and coordinating development. Aiming at the problems that it is difficult to present spatial relationship and inaccurate quantitative evaluation in the evaluation of water resources carrying capacity， this paper takes Wuhu City as an example and selects 16 evaluation indexes such as per capita water resources， water production modulus and rainfall from three aspects of water resources， economy and ecology. DEMATEL is used to determine the influence relationship between each element. Aiming at the defects of traditional entropy weight method， the traditional entropy weight method is improved and its objective weight is calculated. The subjective weight of each index is determined by using network analytic hierarchy process， and the subjective and objective weights are combined by multiplication synthesis method. Finally， the fuzzy comprehensive evaluation method is used to calculate the evaluation value of regional water resources carrying capacity to construct the evaluation system of water resources carrying capacity in Wuhu City. Taking the data of Wuhu City from 2006 to 2016 as an example， the results show that the evaluation value of water resources carrying capacity in Wuhu City ranges from 0.407 1 to 0.637 0， with the lowest value in 2006 （0.407 1） and the highest value in 2016 （0.637 0）. The water resources carrying capacity in this area increased except in 2011 and 2013， and the water resources carrying capacity is in a critical state. This method better considers the characteristics of the network relationship between the evaluation indexes of water resources carrying capacity， improves the defects of the traditional entropy weight method， and combines the subjective and objective weights to evaluate the water resources carrying capacity more reliably and accurately. The research results can provide certain reference for the development and utilization of water resources in the region.

Groundwater depth prediction plays an important role in regional water resources management and utilization ecological environment protection and economic and social development. Groundwater is affected by many factors， and its dynamic change has the characteristics of non-stationary， random and hysteresis. In order to accurately predict the depth of shallow groundwater， five prediction models， including multiple linear regression， gray GM（1，1）， gray GM（1，1） based on Markov chain optimization， BP neural network and BP neural network based on genetic algorithm optimization， are selected to take Zhaozhou County， Heilongjiang Province as an example， and the data from 1980 to 2009 are taken as training samples. Data from 2010 to 2019 are used as test samples， precipitation， evaporation， groundwater exploitation and early stage water level are used as input layers， and groundwater depth is used as the output layer. Absolute error， relative error， mean absolute error， mean absolute percentage error， mean square error and root mean square error are selected as evaluation indexes. The results show that： The average absolute error of BP neural network model optimized by genetic algorithm is 0.13m， the average absolute percentage error is 1.58%， the mean square error is 0.02， and the root mean square error is 0.15. The prediction accuracy is high and the fitting effect is good. Compared with the other four models， it can better simulate the dynamic change of groundwater depth. It provides reference for rational development and utilization of groundwater in Zhaozhou County. The optimization of genetic algorithm improves the training efficiency and stability of BP neural network， and the Markov chain theory makes up for the lack of fluctuation of gray GM（1，1）. The combined prediction model combines the two models， complementing each other’s advantages and significantly improving the prediction performance. Compared with the single model， the prediction result is more accurate， which can provide a new idea for the establishment of groundwater depth prediction model.

Aiming at the problem of lack of systematic study on the whole process of extreme storm flood disasters， this paper puts forward a GIS-based urban storm flood simulation analysis method. Based on the division of sub-watersheds， the “7·20” torrential rain disaster in Zhengzhou City， Henan Province is simulated in the order of rainfall-runoff-inundation， and the disaster situation of buildings and traffic in the study area is evaluated. By comparing the calculation results of the model with satellite image data， it shows that it is basically consistent with the actual range and depth of the flood. It can be seen that the model proposed in this paper can quickly deduce and simulate the large-scale flood inundation in Shifo Town， Zhengzhou City under the emergent situation of missing or low-accuracy data， so as to provide reference for the simulation of urban extreme storm flood disasters， and has practical application values.

In view of the complex terrain environment， wide range of expertise， difficulty in planning and site selection， and problems of inaccurate terrain data acquisition， low coordination efficiency， and schedule management in the water conservancy project， a full life cycle construction application framework based on BIM+GIS technology is proposed. BIM technology is used to establish a refined model， GIS provides real three-dimensional terrain scene information， analyzes the two data fusion problems， and studies the method of integrating BIM models， oblique photographic data and other multi-source data into the three-dimensional GIS platform for integration. The multi-level and multi-dimensional information fusion combining micro and macro， virtual and reality is realized， and a three-dimensional visualized interactive environment is built. Taking a pumped storage power station as an example， it is applied in the planning， design， construction， operation and maintenance stages of a water conservancy project to achieve accurate and coordinated expression of project information such as progress， cost， quality， and safety， which is the full life cycle of a large water conservancy project management application provides a new way of thinking and improves the level of digital construction of water conservancy projects.

Now the analysis of slope stability generally adopts the small deformation finite element method， and the failure criterion is still controversial. Based on the coupled Eulerian-Lagrangian （CEL） approach， a large deformation finite element method， the stability of soil slope is investigated. The effects of mesh size， step time， initial geostatic stress on the calculating results are quantified. The applicability of energy aberration criterion and plastic failure zone criterion is discussed. By comparing the published numerical results， the effectiveness of the CEL model is verified. By comparing the results from different failure criterions， the energy aberration criterion is recommended for the CEL approach. For the plastic failure zone criterion， the critical cumulative plastic strain （P _c） is proposed， which quantifies the determination of stability factor. With the 113 calculated results from the parametric study， an empirical formula is established to calculate the stability factor of soil slopes， whose efficiency is also verified.

The South-to-North Water Diversion Middle Route Project is a strategic infrastructure to alleviate the shortage of water resources in the north， and the project has played a huge comprehensive benefit. The water transmission line of the project is long and there are many river canal crossing buildings. With the increase in project operation time， affected by adverse factors such as freeze-thaw change， concrete carbonization and sediment deposition， the unevenness of the overflow surface of water transmission buildings increases gradually， which may pose a certain risk to the overflow capacity of the water transmission system. Combined with the characteristics of the middle line project， this paper selects the typical water conveyance aqueduct as the test object， and explores and studies the spraying of a non-toxic， harmless and stable nano material on the surface of the building， in order to protect the concrete and reduce the surface roughness of the building at the same time. According to the actual operation of the project， the cooperation scheme of test flow measurement， detection and dispatching is proposed， which is successfully implemented on the premise of ensuring normal and safe water supply. The flow pattern comparison before and after the test and hydraulic simulation calculation is carried out， and the test effect is analyzed and evaluated. The results show that this method can improve the water flow pattern of aqueduct， reduce the surface roughness of aqueduct and improve the flow capacity. The study can be used as a reference for roughness reduction and protection of similar long-distance water transfer projects.

Submersible tubular pump stations are widely used because of their compact structures， straight flow channels and high efficiency. However， it will also produce excessive vibration and noise during operation， which will bring harm to pump station operators， instruments and equipment. With the continuous improvement of our requirements for environmental protection of pump stations， it is necessary to reasonably formulate the acoustic environment control objectives and treatment technical paths of pump stations. The noise of the pump unit of a submersible tubular pump station under multiple working conditions is tested. It is found that the noise distribution characteristics of each working face of the pump station are obvious， and the degrees of exceeding the relevant national standards are different. The excessive noise frequency is mainly concentrated in medium and low frequency. The foundation pit of the pump station can be regarded as a relatively steady-state sound source emitting a large number of medium and low-frequency excessive noises. The study reveals the noise distribution law and sound source characteristics of different working faces of this type of pump station. It provides a basis for the noise research and later treatment of the pump station. It also has scientific guiding significance for improving the operation environment， operation efficiency and modern management level of the pump station.

Pointing to the starting phenomenon of axial flow pump when the outlet water level is higher than the bottom elevation of the hump， this paper selects three influencing factors such as gate opening time， gate pre-opening and super hump height to establish an orthogonal test scheme， and the starting characteristics of pumps are studied in combination with transient flow theory. The research shows that under the super hump condition， the pump head first quickly increases to the maximum， and then gradually decreases to the stable value； the pumping flow starts a back flow， then quickly changes to positive within 3s， and gradually reaches the stable value. The maximum starting head is mainly affected by the hydraulic loss at the gate， so the gate pre-opening has the greatest impact， the gate opening time has the least impact.The maximum backflow flow is also most affected by gate pre-opening，and the other have little influence and the same weight. At last， “the gate opened in 240 s and pre-opened by 30%” determines the optimal starting scheme of the pump.

In order to explore the changes of dissolved oxygen and pH value in shrimp ditches and its effect on crayfish production in shrimp-rice co-cropping， a shrimp-rice co-cropping field is carried out in the shrimp-rice co-cropping field in Yajiao Village， Hubei Province. The experiment took the shrimp-rice symbiosis period from July to September in 2019 and 2020 as the main observation period， and monitored the dissolved oxygen content and pH value of the shrimp ditch in 9 shrimp paddy fields. Through the experiment， it is concluded that the dissolved oxygen contents in the shrimp-rice co-cropping field is related to the aquatic plants in the shrimp ditch， rainfall， and artificial treatment measures. Excessive duckweed in shrimp ditches and long-lasting heavy rain will reduce the dissolved oxygen contents in shrimp ditches. The production of crayfish is positively correlated with the contents of dissolved oxygen as a whole. When the dissolved oxygen is lower than 2 mg/L， the production of crayfish will decrease significantly. The pH value in the shrimp ditch generally varies between 7.3~8.4， and the average pH value of the shrimp ditch in 2020 is lower than in 2019. By comparing the yields， when the pH fluctuates around 7.7， the average yield of crayfish is at a relatively high level.

The RNG k-? turbulence model and VOF gas-liquid two-phase flow model are used to numerically simulate the exhaust process of the air masses at the top of the large-diameter square pipe siphon outlet channel， and calculating the minimum hump average flow velocity v_a required for humps with different aspect ratios to take away the air masses at one time and the average hump flow velocity v_b and discharge time t_b required for air masses fragmentation to completely exhausted.The results show that as the hump aspect ratio decreases， the flow velocity v_a required to discharge the hump air masses at one time also decreases. When the hump aspect ratio decreases from 0.4 to 0.3， the corresponding v_a decreases by 11.6%， but the flow rate is still large. Under a smaller hump flow rate， the whole process of crushing and discharging the air masses is simulated. After a period of time， all the air masses can be broken and discharged， and finally a stable siphon is formed.Within a certain range， the longer the exhaust time， the smaller the flow velocity at the hump. When t_b increases from 120s to 180s， the corresponding v_b decreases by 16.67%.This study is of great significance to the design of the hump section size of the siphon outlet channel and the stable operation of the pumping station.

Henan is an important core area of grain production in China. Improving the modernization level of farmland and water conservancy in Henan is of great significance to ensure food security and national security. According to the five categories of irrigation and drainage， management technology， ecological environment， economic benefits and development support， this paper divides five main indicators and 18 sub-indicators， which constitute the comprehensive evaluation index system of farmland water conservancy modernization level in Henan Province. Based on the entropy weight model and spatial analysis method， the spatial-temporal evolution of farmland water conservancy modernization level in Henan Province is analyzed by using the data of five consecutive years from 2015 to 2019. The results show that from the comprehensive level， the index weight of irrigation and drainage level is the largest. Among prefecture level cities， Zhoukou has the highest level of farmland water conservancy modernization， while Jiyuan has the lowest level. From the perspective of spatial distribution， the spatial distribution of farmland water conservancy modernization level in Henan Province has a significant spatial positive correlation and small spatial heterogeneity. The “insignificant” type area is dominant （more than 50%）， and the HH and ll type areas account for about 35%. In terms of landform， the modernization level of farmland water conservancy in plain areas is generally higher than that in hilly areas. At present， only Zhoukou district， Luohe district and Hebi district have reached the preliminary modernization stage， and the rest of Henan is still in the stage to be strengthened.

Irrigation water price accounting can provide a scientific basis for irrigation water pricing and government subsidies， and is of great significance to ensuring national food security， promoting the healthy operation of irrigation areas and improving agricultural water use efficiency. Taking Baojixia Irrigation District in Shaanxi Province as the research area， with agricultural water volume of water rights as the control， starting from the cost-benefit theory， based on the fixed operating cost and variable operating cost of the irrigation area，this paper constructs a two-part irrigation water price accounting model with basic water price and metered water price. According to the water volume of water rights， planting structure and irrigation quota in the irrigation area， the stepped water consumption nodes are determined， and with the goal of saving water， a three-level stepped water price billing model is established with water-saving water price， conventional water price and excess water price. The results show that the basic water consumption， saving-water consumption and conventional water consumption nodes of Baojixia Irrigation Area are 686， 1 841 and 2 419 m³/hm² respectively， and the basic water price， water-saving water price， conventional water price and excess water price are 409.99 yuan/hm²， 0.405 yuan/m³， 0.598 yuan/m³ and 0.986 yuan/m³ respectively. The research can provide a reference for the formulation of scientific and reasonable agricultural water prices in large-scale irrigation areas in Shaanxi Province.

The coarse particles with particle diameter in millimeter or even centimeter levels will inevitably be sucked into the pipe when the pipeline conveying technology is applied， which will increase the energy loss of pipe flow， decrease the efficiency of pipe transport. Then， the coarse particles tend to deposit in the pipe， which will threaten the safety of pipe transport. The study of the fluid and coarse particle hydraulic conveying in the pipe is very significant for the efficiency and safety improvement of pipe transport. Combined with the latest research trends at home and abroad， this paper reviews the basic theories of fluid and solid movements， physical experiments， the mutual feedback between fluid and solid， and numerical simulations. The characteristics of the sliding and sedimentation movements of coarse particles via physical experiments and the studies of numerical simulations based on the CFD-DEM coupling methods are deeply analyzed. Based on an overview of current research results， it is pointed out that the future studies should focus on the evolutionary law of key parameters of theoretical equations， the movement mechanisms of pebbles and high sediment concentration flow in the pipe， complex particle shape modeling， determination of numerical simulation parameters， the effect of flexible boundary condition of pipeline， the transport law of cohesive and crushable particles， the relationship between the energy evolutions of fluid and those of solid， the application of high precision turbulence model in numerical simulation.

The hydro-turbine regulating system plays a key role in the safe and stable operation of hydropower plants. Improper regulation parameters can weaken the damping of the system and induce hydropower unit power angle oscillation behavior. In order to ensure the stable operation of hydropower units， this paper proposes a fuzzy sliding mode control strategy based on improved reaching law and sliding manifold. Firstly， considering the mutual influence between the transient characteristics of hydraulic and electromechanical systems， a hydro-turbine regulating system containing the internal characteristics of the hydraulic turbine with elastic water hammer and the third-order generator model is established， and the oscillation characteristics of the system under different operating conditions are analyzed. Secondly， the stability of the system rotor angle is enhanced by introducing Δδ and ΔV _t into the sliding manifold to improve the influence of the controller output on the system damping. On this basis， taking the mechanical power of the system as the reference index， a variable speed reaching law based on the exponential law adjustment is designed， so that the convergence speed can be adjusted in time with the change of working conditions. Simulation results under different working conditions show that the proposed control law can effectively improve the power-angle oscillation behavior of the hydropower unit and suppress the occurrence of low-frequency oscillation of the system when the system is subject to power disturbance， which enhances the stability of the system and the robustness of the controller.

This paper studies the dynamic efficiency of hydropower by decomposing the Malmquist index of hydropower in the Yangtze River mainstream region from 2014 to 2017， and uses the two-hierarchy Meta-frontier DEA model to conduct a static study on the technology gap ratio of hydropower in the Yangtze River mainstream region in 2017. The results show that the technology progress efficiency of hydropower in the Yangtze River mainstream region from 2014 to 2017 is generally on the rise， and the scale efficiency and total factor productivity of hydropower in the upper stream are lower than those in the middle stream and lower stream. In 2017， the technology gap ratio in the lower stream of the Yangtze River was lower than that in the upper stream and middle stream， and the geographical conditions were the main causes of the low technology gap ratio in the lower stream of the Yangtze River.

In order to realize the feedback analysis of reinforcement effect from seepage monitoring data of the earth rock dam， taking a reservoir main dam as an example， a three-dimensional seepage model is established for finite element calculation， and the seepage condition of earth-rock dam under normal storage level and design flood level is simulated and analyzed. The analysis of monitoring data shows that the finite element calculation results can reflect the relatively real seepage field of the earth rock dam. The overall anti-seepage effect of the earth rock dam after danger removal and reinforcement is good. There are potential seepage overflow points in the downstream of the right bank of the dam and the upper part of the ridge drainage. The calculation results of the seepage field of the main dam of the reservoir accord with the seepage law of earth-rock dam. The results provide a reliable scientific basis for the analysis of dam seepage.

The coastline of the Three Gorges Reservoir area has many functions and is an important carrier for the construction of national economic facilities such as ports， wharves， roads and Bridges. The scientific and rational use of coastline resources is particularly important for regional economic development. Through the analysis， the main categories of shoreline utilization projects in the Three Gorges Reservoir area are clarified， and the benefit evaluation systems of port shoreline utilization projects， flood control and bank protection and ecological improvement projects in the Three Gorges Reservoir area are constructed respectively， and the corresponding benefit quantitative calculation models and estimation methods are put forward. The benefit quantitative evaluation and analysis of port shoreline utilization projects flood control and bank protection and ecological improvement projects in typical districts and counties of the Three Gorges Reservoir area are realized. This method system can provide reference for scientific planning， high quality and efficient development and utilization of the reservoir shoreline resources， ensuring the good ecological environment and promoting the sustainable development of the reservoir society and economy.

The change of moisture content has a great influence on soil properties in practical engineering. In order to determine the influence of water content on mechanical properties of eco-bag reinforced soil and parameters of Duncan-Zhang Model， eco-bag reinforced soil with different water content is taken as the research object. The variation of Duncan-Zhang Model parameters with water content of eco-bag reinforced soil is studied by the triaxial compression test. The experimental results are as follows. Firstly， the stress-strain relationship curves of eco-bag reinforced soil under different water contents show hyperbolic characteristics. Deviational stress with axial strain of 15% is selected as failure strength value for the test. It is found that the failure strength decreases with the increase in water contents. Secondly， the variation of water content has different degrees of the influence on the parameters of Duncan-Zhang Model. With the increase in water contents， the cohesion decreases in a quadratic function relation， and the internal friction Angle， K value and n value all decrease in a linear relation. The failure ratio ranges from 0.828 to 0.990. Thirdly， the initial tangent modulus reflects the resistance of soil to deformation at the initial stage of the stress-strain relationship curve. And the initial tangent modulus of eco-bag reinforced soil decreases with the increase in water contents. At the same time， the empirical formula of initial tangent modulus with water content is obtained.Fourthly， the applicability of the research results is found by analyzing the sample size effect. These conclusions provide a theoretical basis and parameter support for the design and numerical simulation of ecological bag slope protection engineering.

In view of centralized access problems of a large number of small hydropower stations， in-depth analysis of provincial power grid business characteristics， an improved business-driven load balancing task allocation algorithm is de-signed. Adopting master-slave database server plus load balancing technology， the algorithm is designed which used power grid data storage access control policy and IP_hash combined with Fair. This algorithm effectively separates read and write operations， strengthen effective acceptance rate of first request during task peak period， and greatly improve the response efficiency of data reporting and query. It not only completely solved the problem of web page jammed， but also stabilized the response time for centralized access from 30 seconds to less than 5 seconds， greatly improves the user experience and the operating efficiency of the system.

Crest cracking is one of the most common damage types for high core rockfill dams. Cracking risk of dam crest is closely related to the duration of abnormal deformation state. In this paper， a methodology for dynamic risk evaluation and early warning of crest cracking for high earth-rockfill dams is proposed. The abnormal state of the dam crest is identified by the settlement inclination method. The exponential distribution is adopted to represent the probability distribution of the duration TAS of abnormal state before crest cracking. The dam crest cracking risk assessment model is constructed to realize real-time analysis of dam crest cracking risk and probability-based cracking time estimation. Bayesian estimation and updating of probability distribution of the parameter λ in the risk model， according to observed durations of abnormal state before crest cracking. Validity of the methodology is illustrated and verified by the case study for a high core rockfill dam. Based on the dam crest cracking observed at the time of the high water level over the years， the parameter λ of risk model is updated to gradually reduce the dispersion of the probability distribution， and the confidence interval of the dam crest cracking probability estimation is also reduced. The dam cracking time is predicted by the statistical analysis of the corresponding cracking probability when the dam crest is cracked， and the early warning of crest cracking is issued based on the lower limit of the confidence interval of the cracking time estimation. The result shows that the method can predict the cracking time of the dam crest accurately and issues an early warning of crest cracking more than 20 days in advance.

The vertical slot fishway is one of the main forms of fish migration assistance structure in the application of hydraulic engineering. Compared with the traditional fishway （eg.weir-flow fishway， Daniel fishway）， this kind of fishway is easier to create flow patterns that facilitate fish migration， and it’s suitable not only for small streams but also for large watersheds. Furthermore， it is eco-friendly to all kinds of fish species， including those with weak swimming ability or small size. As an important parameter in fishway design， slope gradient directly affects the hydraulic characteristics in the chamber of the fishway and is also related to the construction cost. In the present study， based on the RNG k - \epsilon model derived from Navier-Stokes equations， the effect of the slope gradient of the vertical slot fishway on the velocity and total kinetic turbulence is studied numerically. Moreover， the variation of velocity and turbulent kinetic energy distribution with different slope gradients is systematically studied. The results indicate that， with the slope gradient of the fishway increases， the recirculation zone of h_s is reduced by the extrusion range of the jet， and its value decreases from the initial 55.11% to 15.22%， leading to a significant reduction of the left return zone， which is very unfavorable for fish to rest during migration. The flow pattern in the h_b plane， on the other hand， is less affected by the slope gradient and does not change much. The flow field is less affected in h_s and h_b planes when the slope changes from 1.5% to 4.2%. However， when the slope gradient increases to 6.67%， the area of the low-speed recirculation zone in the h_s plane decreases significantly compared with that in the h_b plane， due to the inflow of the high-speed mainstream. Especially for the left recirculation zone， the size decreases by nearly 20% while the slope gradient increases to 6.67%， and the simultaneous change of flow velocity and flow pattern reflect the three-dimensional characteristics that emerge under this kind of slope gradients. The maximum flow velocity at the vertical slot varies with the slope and exceeds 2 m/s with a slope gradient of 8.33%. Under this kind of slope gradients， the difference in flow velocity between the main flow area and the recirculation area is extremely increasing， and the maximum velocity in the main flow zone increases from 0.84 to 1.78 m/s. However， the minimum flow velocity and the maximum flow velocity in the recirculation area are less affected by variation of the slope gradient. The magnitude and distribution of turbulent kinetic energy at 1.5% and 4.2% are more suitable for fish migration than the other two larger slopes. The results also indicate that the h_s plane has fewer areas with high turbulent energy unsuitable for fish migration （>0.05 m²/s²） at larger slopes than h_b due to the dispersion of the mainstream. Meanwhile， the average turbulent kinetic energy also increases with the slope gradient， and the corresponding maximum value reaches 0.035 1 m²/s² at the slope gradient of 8.33%.

In order to improve the identification accuracy of vibration faults of hydropower units， a vibration fault diagnosis method based on CEEMDAN-ELM-Adaboost is proposed in this paper. Firstly， the original vibration signal of the unit is denoised by fully adaptive noise ensemble empirical mode decomposition （CEEMDAN）， and the sample entropy of the main IMF component is extracted. Then， the hybrid feature vector is constructed by combining the conventional time-domain and frequency-domain features. Finally， the extracted mixed feature vectors are input into ELM-Adaboost to build an intelligent fault diagnosis model for hydropower units， so as to realize high-precision classification diagnosis of vibration faults of hydropower units. Taking the rub-impact fault of the runner room of a hydropower station as an example， this paper proves that the proposed fault diagnosis model based on CEEMDAN-ELM-Adaboost has advantages over the traditional model.