The existence of black and odorous water body in rural areas has been hindering the development of rural economy and the improvement of rural residents' living quality. In this paper， information is collected from 84 water bodies in rural areas of Henan Province by means of field investigations and questionnaires. It refers to the black smelly degree， water area and pollution type. The black and odorous water in Henan Province in mild black smelly accounts for 27.38%， 53.57% is moderate black smelly， heavy black smelly water accounts for 19.05%，the overall water presents light to moderate black odor characteristics. After analyzing five types of pollution area and the characteristic， it is found that industrial wastewater pollution has a higher positive correlation with population density than other four pollution types. There is a negative correlation between water area and pollution degree. Through understanding the basic information of rural polluted water in Henan Province， it will promote the treatment and restoration of black and odorous water bodies in rural areas in Henan Province.

Soil and water loss is serious in the Loess Plateau， and shallow surface landslides mostly occur in areas with well-developed vegetation after rainfall according to the field investigation. It is speculated that it is related to the disintegration which is the water sensitivity of the loess. In order to explore the mechanism of the disintegration of slope soil and the role of grass roots in disintegration， disintegration tests of root Malan loess and rootless Malan loess under different hydrodynamic conditions are designed. As a result， water enters the Malan loess and expands in the pores， cracks are generated and expanded and extended， and the soil body disintegrates and eventually breaks down. The effect of moving water on soil includes disintegration and transportation. The effect of still water on soil is mainly disintegration. The following conclusions are drawn： ①The disintegration of moving water on the soil is more intense. ② The disintegration of rootless Malan loess is determined by the pore structure. The roots grow along the pores and fissures， which improve permeability， form dominant flow in the soil， and weaken the disintegration of the soil. ③ Under the dynamic and static water environment， the root-bearing soil reduces the disintegration of the soil. Besides， the higher the rooting rate is， the more the disintegration is weakened.

Aiming at the difficulties of “unmanned governance， no money governance， unattended governance， and unorganized governance” in rural pits and ponds， taking the rural revitalization strategy as the ideological guide， combing the focus of the river management system， according to the efficient management of rural ponds， the ecological importance of a livable environment， we create a rural civilization， promoting industrial prosperity， and realizing prosperity for farmers. On this basis， taking the rural pits and ponds in Suixian County， Henan Province as an example， with the goal of comprehensively promoting the long-term development of the rivers and lakes to promote rural revitalization， we organically integrate small and micro-water remediation and rural revitalization， and implement water and river governance. According to the classification of distant village ponds and near village ponds， this paper puts forward corresponding construction models and construction suggestions for rural pits. In addition， from two aspects of “rule of man” and “rule of law”， “consolidate the foundation of human rule and deepen the rule of law” management The model provides a variety of paths for the treatment of rural pits and ponds in the Huanghuai Region and helps rural revitalization.

The Huangshuigou Water Transfer Project has changed the hydrodynamic conditions of Bosten Lake， which causes a different mineralization in Bostan Lake and downstream. To explore the influence and the optimal operation mode of the project， this paper applies MIKE21 software to establish a two-dimensional hydrodynamic water quality model. Duo to the simulation results of five scenarios， the Huangshuigou Water Transfer Project can lower the level of mineralization and the uneven spatial distribution in Bosten Lake. The annual mineralization in Bosten Lake would reduce by 86 mg/L by diverting 3×10⁸ m³/a runoff from Kaidu River to Huangshuigou River， which also leads to the mineralization relocating from Bosten Lake to downstream. Fortunately， the outflow mineralization degree has changed from 912 mg/L to 940 mg/L， which means a small risk to the irrigated area downstream.

The gravel filter effects on suspended matters and the control effect on clogging are analyzed by using storm water gravel infiltration column experiments. Three groups of contrast experiments are used to analyze the influence on controlling clogging of the gravel thickness and the gravel particle difference.The results show that gravel filter plays an important role in controlling clogging and improving recharge efficiency by the great removal ability on the suspended matters in the recharge water. The choices of the thickness and the particle size of the gravel filter played important roles in control effect on clogging， which is manifested as the thicker the graver filter， the better control effect.

The rigid steel and flexible spring materials are used to model different types of aquatic vegetation. The effects of type and submergence of aquatic vegetation on the vertical flow velocity distributions of rivers are explored by using physical experiments. The results of physical experiments show that the vertical flow velocity distribution of rigid materials under different submergence degrees exhibits a similar trend as that of flexible ones. The vertical flow velocity distributions of both the rigid and flexible materials exhibit stratification phenomena. The critical values of the stratification phenomena for the different types of aquatic vegetation are different. This is due to the different mechanical interaction mechanisms between the aquatic vegetation and the water flow for the different types of aquatic vegetation.

Engineering disturbance seriously damages the original topography and ecological vegetation， exacerbates the deterioration of the ecological environment and the degradation of the ecosystem. In order to reduce soil erosion and shallow landslides， accelerate vegetation restoration and ecological restoration， this paper studies the vegetation community restoration in the engineering disturbance zone meaningful subject. In this study， the Shikui River， which is in a natural recovery period after ecological governance， was selected as the research object. Seasonal monitoring and field investigations were carried out on vegetation restoration at different water levels in the project disturbance area. The types and numbers of vegetation restoration on river slopes， vegetation community types and their Structure. According to survey statistics， there are 43 vegetation types above the normal water level and only 17 species below the normal water level； the Pielou evenness index above the normal water level is 0.774， and the Pielou evenness index below the normal water level is only 0.397； Vertically distributed vegetation community structure， all herbs below normal water level. It shows that the change of water level has a great impact on the vegetation restoration in the project disturbance area. The change of water level not only affects the types and quantity of vegetation restoration， but also affects the vegetation's life form and growth type.

In order to solve the problems of stormwater management model （SWMM） in calibration process， such as complex parameters and tedious process. This paper takes a certain block of Xining city as an example to establish SWMM model. Morris screening method is used to analyze the sensitivity of parameters， and artificial calibration is carried out according to the results of sensitivity analysis. In addition， BP neural network is used to calibrate the model， and parameter sensitivity is combined to optimize it. Through the analysis of three calibration schemes， the results show that the relative sensitivity of hydro-hydraulic module parameters is basically same， among which the more sensitive parameters are sub-catchment Area， Imperv and Destore-imperv. Moreover， the sensitivity of model parameters is different under different rainfall conditions. The optimized BP neural network parameter calibration method has the best simulation effect and the Nash coefficient is the largest. On the one hand， the method which combines with sensitivity to optimize BP neural network can improve the accuracy of BP neural network calibration， on the other hand， it can improve the efficiency of traditional artificial calibration.

Aiming at the randomness of subjective weighting in the evaluation of lattice order theory， the game theory thought is combined with fuzzy analytic hierarchy process and entropy method to construct a lattice order theory evaluation model based on game theory. Taking the optimization of water resources allocation scheme in the starting area of Xiong'an New District as an example， this paper fully considers the uncertainty of future development， four representative schemes under normal scenarios and special scenarios are selected as the research objects， and the game theory combination is weighted. The evaluation results of lattice order theory are compared with the results of fuzzy analytic hierarchy process-lattice order theory evaluation model and entropy value method-lattice order theory evaluation model. The results show that the optimal results of the game theory combination weighting order theory evaluation model have better consistency than other methods， and the evaluation results are scientific.

Taking the Lancun Station to Fenhe Erba Station watershed of Fen River as the study area， the SWAT distributed runoff simulation model in the research area is established. The SUFI-2 algorithm in SWAT-CUP is used for model sensitivity analysis and parameter calibration. Then the calibrated model is further applied to runoff response analysis under the condition of climate change. The results would provide a theoretical basis and technical support for regional water resources management decision. The results of runoff simulation show that all the accuracy evaluation indexes of the simulation period meet the standard class B. SWAT model has good applicability in runoff simulation in the study area. The runoff response analysis under the condition of climate change shows that the runoff change is negatively related to the temperature change， and with the increase in temperature variation， the rate of runoff decrease slows down， and the temperature effect weakens. The runoff change is positively related to the rainfall change， and with the increase in rainfall variation， the runoff increases with the increase in acceleration rate， the effect of precipitation is strengthened. For the same runoff response， the relationship between temperature and rainfall is basically linear， that is to say， the runoff effect of 0.5 ℃ increase in temperature is equivalent to that of 0.49% （range of change 0.38%~0.67%） decrease in rainfall.

The comprehensive evaluation of water use efficiency is the basic work evaluating regional water use level and water-saving effect， which is of great significance to implement the policy of “water-saving priority”. In order to scientifically evaluate the regional water use efficiency level and overcome the fuzziness and randomness in the evaluation process， this paper constructs a cloud model based on the game theory and selects evaluation indicators from four aspects of comprehensive， domestic， industrial and agricultural water efficiency to evaluate the water use efficiency level of Jinhua City in 2018. The results show that in 2018， the water use efficiency of Jinhua City and its nine counties are in a state of “high efficiency”， which is consistent with the evaluation results of matter-element analysis method. The model has good applicability and feasibility. The evaluation results can provide a reference for Jinhua City to promote national water-saving social innovation pilot work and related planning research.

The identification of similar floods by statistical methods and the mining of historical flood data in the river basin can be used to prolong the forecast period of floods and thus provide a guidance for the pre-discharge operation of reservoirs. In this paper， watershed runoff characteristics， meteorological causes and seasonal factors that affect flood formation are analyzed. Cumulative rainfall， flood rise time and early average flow are screened out through index clustering to classify historical floods as similarity indexes， and most similar floods are optimized with grey correlation degree and the flood volume is transferred. In Xinfengjiang Reservoir watershed as an object， games during the 212 flood events of 100 flood to validate the proposed method， the results show that in addition to the small scale and a handful of great magnitude of floods， the prediction error of the actual overall slants small， with 59 of flood forecast error is less than 30% of the actual， focuses on the “dragon boat water” period of the second category of floods， the least prediction error in three categories. This method is helpful to predicting flood inflows in advance and has important reference values for flood forecast and operation of multi-year regulated reservoirs in South China.

The water resources in the cold basin with permafrost as the main underlying surface are sensitive to climate change， taking the source area of the Yangtze River for instance， according to the base flow analysis results of runoff from Zhimengda Hydrological Station from 1966 to 2015 by the digital filter method， the variation rules of runoff and its different components in the source area of the Yangtze River are clarified. Furthermore， Granger Causality Test and Cumulative Slope Method are used to analyze the influences of precipitation and temperature on runoff. The results show that in recent 50 years， the total runoff of the Yangtze River presents an increasing trend， after the mutation point in 2004， the annual average runoff increased by 3.649 billion m³， and underground runoff and surface runoff contributed 50% respectively. The continuous increase in temperature in the last 50 years is the Granger cause of runoff variation， which is helpful to the prediction and analysis of runoff composition variation. Comparing before and after the mutation point， the surface runoff is influenced by the changes of precipitation， and also the freezing-thawing process of soil water is changed after infiltration because of the continuous increase in temperature， the contribution rates of temperature for the changes of underground runoff and surface runoff are respectively 90% and 76%， higher than that of 68% and 57% of the change of precipitation. Under the background of climate change， the continuous increase in temperature changes the precipitation form and soil water freezing-thawing process， and which is the main reason for the change in runoff composition in the permafrost area.

Based on the evaluation index of Ningxia water resources system and social adaptive capacity system， a coupling coordination degree model is constructed， and the index weight is determined by using the improved entropy method. The relationship between water vulnerability and social adaptive capacity of Ningxia from 2010 to 2017 is analyzed. Specifically， the following conclusions are drawn： ① From 2010 to 2017， water resource vulnerability in Ningxia showed a trend of reduction. In 2017， the comprehensive evaluation value of social adaptability was the highest， while in 2012， it was the lowest. ② From 2010 to 2017， the coordination degree of water resource vulnerability and social adaptability in Ningxia is basically in four states： high-quality coupling， good coupling， intermediate coupling and primary coupling. ③ From 2010 to 2017， the degree of coupling coordination between water resource vulnerability and social adaptability in Ningxia is in six types： high-quality coupling coordinated development， good coupling coordinated development， intermediate coupling coordinated development， primary coupling coordinated development， reluctant coupling coordinated development， and near imbalance and decline.

Based on 18 GCMs of CMIP5， precipitation data is generated by the LARS-WG downscaling model， and 11 extreme precipitation indices are calculated under the two emission scenarios of RCP4.5 and RCP8.5 from 2041 to 2070， which are averaged by the Bayesian model averaging method and compared with the historical data in Zhejiang Province during the baseline period from 1971 to 2000. This study explores the spatial-temporal variations of extreme precipitation in Zhejiang Province. The results are as follows： ① The precipitation in Zhejiang Province tends to be more concentrated， which has an overall trend for increase in extreme precipitation amount and number of rainfall days. The change of R95pTOT and R99pTOT is the most representative with the largest increase related to the reference period. R20 mm and R30 mm increase obviously higher than R10 mm. ②The spatial distribution of precipitation tends to be extreme， and extreme precipitation decreases from the eastern coast to the west. The eastern coast will experience more and stronger precipitation in the future than other regions. ③ The extreme precipitation indices have similar changes under RCP4.5 and RCP8.5 emission scenarios compared with the baseline period. In comparison， the increase in extreme precipitation intensity and frequency under RCP4.5 emission scenario is more obvious， which means the probability of the occurrence of extreme precipitation events is higher under RCP4.5 emission scenario.

Based on the daily precipitation data of 29 meteorological stations in Yunnan from 1960 to 2014， five statistical indexes are calculated， including the Concentration Index （CI）， Precipitation Concentration Index （PCI）， Precipitation Concentration Degree （PCD）， Precipitation Concentration Period （PCP） and Coefficient of Variation （CV）. The relationship between each index is analyzed， and the spatial distribution of each index is discussed. The results show that ① CI ranges from 0.62 to 0.71， with an average of 0.67， and the daily precipitation is highly concentrated. The correlation coefficients between CI and annual precipitation and precipitation days are -0.50 and -0.93， respectively， which have a significant negative correlation （α=0.05）. CI is larger in areas with less annual precipitation and precipitation days. The correlation coefficient between CI and longitude is 0.64， which has a significant positive correlation （α=0.05）. ② PCI ranges from 11.95 to 21.48， in which 3% of the stations are highly concentrated， 52% of the stations are concentrated， and 45% of the stations are moderately concentrated. PCD ranges from 0.30 and 0.74， and PCD in northwestern and southeastern Yunnan is smaller than that in other parts of Yunnan. The results of PCP analysis show that the precipitation in Yunnan is mainly concentrated in July and August. ③ CI， PCI and PCD pay attention to the grade distribution and concentration degree of precipitation respectively， while PCP pays attention to the period of concentration. The spatial distribution of PCI and PCD is basically the same， and the correlation coefficient between the two is 0.90， which has a significant positive correlation （α=0.05）， so they can replace each other to some extent. The annual grade distribution， concentration degree and concentration period of precipitation can be well described by using CI， PCI and PCP. ④ CV is between 0.11 and 0.21， the interannual variation of precipitation decreases with the decrease in latitude and the increase in annual precipitation， the correlation coefficient are 0.39 and -0.74 respectively， while the annual precipitation decreases with the increase of elevation and latitude， the correlation coefficient are -0.45 and -0.53 respectively.

Based on hydrological alteration diagnosis and the inconsistency of hydrological frequency calculation principle， research on distribution of precipitation and temperature in Karst under a changing environment， the trend and key factor are analyzed， and the effects of changing environment are confirmed， the correlation between karst development and precipitation and temperature is discussed. The results show that ① the trend of annual precipitation are down in all stations， the trend of annual mean temperature are rising in most stations， and the series of annual precipitation and annual mean temperature is negative correlation. ② There are alterations in 9 of the all stations on annual precipitation series， there are alterations all of stations on annual mean temperature series. ③ Some reasons lead to the alteration of climate or human activities. ④ The change of annual precipitation and annual mean temptation on different karst development are consistent.

Due to rainwater retention is the main approach to the rainfall-runoff reduction effect of green roof， rainwater retention capacity is an important effective index. Considering the characteristics of rainfall-runoff process and the varying process of rainwater retention capacity during the drought period， a unit hydrograph model to simulate rainfall-runoff process is proposed based on the saturated infiltration theory， and an exponential function of rainwater retention capacity during the drought period is presented based on soil-water evaporation theory. Field rainfall-runoff monitoring on green roof is carried out and the results show that the green roof has a significant impact on runoff volume reduction effect. The runoff volume reduction effects for each rainfall event of green roof are simulated by using the exponential function of rainwater retention capacity during the drought period， and then the rainfall runoff processes are simulated by using the unit hydrograph model. The simulation results show that the trends of the estimated and measured values are consistent.

A large number of small reservoirs built in the basin may change the natural characteristics of the flood， and the data of small reservoirs are often missing or incomplete， which makes it difficult to consider the regulation and storage function in flood forecasting， and brings difficulties to flood forecasting. Based on RS， GIS and SVR algorithm， the relationship model of topography and geomorphology parameters and reservoir capacity is constructed to calculate the small reservoir capacity information in the area where the reservoir data is missing. Based on the quantitative generalization of the impact of small reservoirs on flood detention， the XAJ-reservoir （XAJ-R） model is established. The results show that： ① there is a strong correlation between the total storage capacity of small reservoirs and the characteristics of topography and geomorphology， and the established model of topography and geomorphology parameters and reservoir storage capacity has a high accuracy， which can be used to calculate the storage capacity of small reservoirs with missing data. ② After adding the reservoir retention module， the flood prediction accuracy of XAJ model is improved to a certain extent. The research findings can be used as a reference for real-time flood prediction in the area affected by small-scale water conservancy projects.

Water and fertilizer， two major factors affecting rice yields， have always been the focus of researchers. Zhanghe Irrigation District of Hubei Province is selected as the research area， and the rice variety Quanzaoyousimiao is used as the test material， and the barrels are used for cultivation. The main treatments are W1 （CF， continuous flooding irrigation） and W2 （AWD， alternate wetting and drying irrigation）， and the secondary treatment are traditional fertilizer and slow-release fertilizer with different levels. Experimental studies on rice barrel cultivation under different irrigation modes coupled with traditional fertilizer N1 and fertilization levels ［F（0.5），F（0.75），F（1），F（1.25），F（1.5）］ of slow-release fertilizer are carried out from June to September in 2019. The results show that different water and fertilizer treatments have no significant effect on rice plant height， chlorophyll SPAD value， but plant height and chlorophyll SPAD value are positively correlated with slow-release fertilizer levels in a certain range in general， and under alternate wetting and drying irrigation mode， the plant height and chlorophyll SPAD value of N2F（1.5） is significantly different from N2F（1）’s and N2F（0.75）’s， specifically， the N2F（1.5） level is significantly higher than N2F（1），N2F（0.75） levels by 71% and 91%， respectively. Different water and fertilizer treatments have a significant effect on yield， and the highest yield， continuous flooding slow-release fertilizer treatment W1N2F（1） could reach 18 170.29 kg/hm²， treatment of alternate wetting and drying traditional fertilizer W2N1 followed by 17 826.86 kg/hm². The yield of continuous flooding irrigation model is 6.43% higher than that of alternate wetting and drying irrigation. Under traditional fertilizer， the yield of alternate wetting and drying irrigation is 3.7% higher than that of continuous flooding irrigation， and the effect of slow-release fertilizer on yield is the most significant. The continuous flooding irrigation mode is more suitable when applying slow-release fertilizer in rice cultivation.

In order to study the effects of different lower limits of soil water content on the growth， water consumption， yield and water productivity of industrial tomatoes in Xinjiang province，a pit test is carried out with industrial tomatoes as the research object. The results show that the irrigation times and total irrigation number of industrial tomatoes increase with the increase in the lower limit of soil water content. When the planned wet layer is set to a fixed depth of 40 cm， the irrigation quota increases with the decrease in the lower limit of soil moisture content. Plant height， leaf area index and chlorophyll content of industrial tomatoes increase first and then decrease during the growth period. The lower limit of soil moisture content suitable for industrial tomatoes physiological indexes is 65%， corresponding water consumption was 405.0 mm， irrigation times are 7， and irrigation quota is 57.8 mm.

In order to solve the problem of applying nitrogen fertilizer in sandy soil in Heilonggang Area of Hebei Province， no nitrogen fertilizer is applied， and the total nitrogen application rate is 240 kg/hm² nitrogen base-topdressing ratio treatments at 3∶7， 4∶6， 5∶5， 6∶4 and 7∶3， respectively. The water and nitrogen use efficiency of wheat and the dynamic changes of soil water content， water storage and nitrogen are studied. The results show that the highest water use efficiency （Wue） and nitrogen production efficiency （Nue） of sandy soil at 3∶7 are 21.00 kg/（hm²·mm） and 24.36 kg/kg， respectively. Soil water content increases with the increase in soil depth and accumulates at 60~80 cm. The soil water storage， NH₄ ⁺-N and NO₃ ^--N of the treatment with nitrogen base-topdressing ratio of 3∶7 had higher values in the growth period of wheat， which could provide sufficient water and nitrogen nutrition for the growth and development of wheat. The accumulation of NO₃ ^--N is the highest in 0~100 cm soil layer at jointing stage， and there is a risk of downward leaching of NO₃ ^--N， but the accumulation of NO₃ ^--N decreases with the growth of wheat. Therefore， it is relatively reasonable to choose the nitrogen fertilizer base-topdressing ratio of 3∶7.

With the comprehensive reform of agricultural water price in our country， the mechanism of agricultural water price has been gradually formed in some places， but many places are still exploring it. As an experimental area of comprehensive reform of agricultural water price in Fengshui Area of South China， Jingmen has been exploring for more than three years， the agricultural water price mechanism consists mainly of agricultural water right system， water pricing model， pricing method， water charge collection and management， and water-saving reward， etc. . On this basis， the paper puts forward relevant countermeasures and suggestions， aiming to provide a reference for the formation mechanism of agricultural water price under the complex geomorphologic conditions in the south water-rich area.

Based on Luanhe downstream irrigation area， the underground water simulation model （GBM） and optimum model were set up. Through model verification， model coupling and optimization control calculation， the groundwater dynamic variables， reasonable groundwater regulation， land optimal use and crop optimization layout scheme were achieved. The results show that from 2015 to 2030， the net groundwater storage would recover 10×10⁴ m³/ years， which will recover to 79.2%. It is predicted that the groundwater drop will be basically restored by 2030. The results of crop optimization in the irrigation area show that the benefit of crop planting would be 3.332 61 billion yuan by 2030. Compared with the traditional planting pattern， the total income from crop cultivation has more than doubled. The ecological environment， social and economic benefits are very remarkable. The research methods can be used as a reference for formulating agricultural water management strategies.

In order to reveal the mechanism of straw cover on the water and salt regulation of coastal saline soil， the effects of different straw coverage （0， 0.3， 0.6， 0.9 and 1.2 kg/m²， denoted by CK， straw A， straw B， straw C and straw D， respectively） on soil water and salt transport and evaporation rate are studied through indoor simulation experiments. The results show that straw mulching increases the moisture content of the surface layer and soil profile， and the effect of increasing soil moisture increases with the increase in straw coverage. The average moisture content of straw A， straw B， straw C and straw D profiles are higher than CK by 41.2%， 52.3%， 65.7% and 58.5% during the experiment； straw mulching can suppress the accumulation of surface soil salt and effectively regulate the soil profile salt distribution. The lower the salt content， the more balanced the salt distribution in the soil profile： the electrical conductivity of 0~2 cm soil on the surface of CK， straw A， straw B， straw C and straw D is 246.3%， 242.8%， 138.4%， 40.5% and 47.6% higher than the 3~5 cm conductivity， respectively. At the end of the experiment； the soil evaporation rate and cumulative evaporation decrease with the increase in straw coverage. During the experiment， the average evaporation rate of CK， straw A， straw B， straw C and straw D treatments are 1.79×10^-3， 1.64×10^-3， 0.93×10^-3， 1.35×10^-3 and 0.76×10^-3 mm/min， the cumulative evaporation is 17.79， 20.30， 14.20， 14.57 and 10.27 mm， and the effect of straw coverage on the evaporation rate and cumulative evaporation is more obvious in the early stage of evaporation.

Samples of surface water and groundwater were collected from typical agricultural areas in the Huaxi River Basin during the normal and dry seasons. Combined hydrogen and oxygen isotope tracer technique with land use type， the supplying sources of in different water， seasonal changes and its influence factors are analyzed. Based on spatial interpolation， the main hydrological processes under the influence of different land use types are expounded. The results show that： ① different waters in the research area are mainly supplied by local atmospheric precipitation， the Moon Lake Reservoir is remarkably affected by evaporation， and δD and δ ¹⁸O values of surface water and groundwater in the normal season are generally higher than those in the dry season. ② The δD and δ ¹⁸O of groundwater show obvious spatial differentiation characteristics during the dry and normal seasons. The paddy field and water reservoir in the west area are flourished in δD and δ ¹⁸O， but the dry land concentrated area in the east are depleted in δD and δ ¹⁸O， thus the land use has a significant impact on environmental hydrological processes in this research area. The results of this study are helpful to catching on the impact of surface water on groundwater under different land uses and provide a scientific basis for watershed management.

With the development of economy and society and advancement of urbanization， great changes have taken place in China's rural land structure， population structure， planting structure and rural capital. The large-scale circulation of agricultural land promotes the rise of new management entities. In the south of China， influenced by natural conditions and traditional ideas， farmers’ cooperation and participation in water management are not enough， the endogenous power and cohesion of water organization and the terminal water management system are relatively weak， which cannot meet the high-quality requirements of new management entities for water supply services. Meanwhile， the terminal water management of southern gravity irrigation area ushers in opportunities and challenges. Based on the operating characteristics of new management entities， the influence on the management of terminal water management in southern gravity irrigation area is analyzed from the aspects of the construction and management of farmland water conservancy， water management and so on. At the same time， scientific and effective management suggestions are put forward from the angle of encouraging the participation of new management entities， strengthening the construction of grassroots water management teams and improving the water fee calculation and collection mechanism.

The bank slope of the reservoir is affected by seepage erosion caused by the reciprocating movement of water flow for a long time， such as atmospheric circulation and water level regulation. Especially in the water conservancy project in the red bed area in southwest China， the long-term water immersion and the dry-wet cycle result in the serious deterioration of the red bed mudstone characteristics. Based on a reservoir in the red bed area of southwest Sichuan Province， the hydration characteristics of red bed mudstone and progressive damage and failure under dry and wet cycles are deeply studied through laboratory tests and theoretical analysis. The results show that the microstructure of red bed mudstone becomes looser after water-rock interaction. The expansion and deformation of red mudstone in the initial stage of flooding is significant， and the vertical deformation of rock mass is further aggravated by the dry-wet cycle. The compressive strength and cohesion of the red-bed mudstone decrease linearly with the number of dry and wet cycles and decrease with the concave quadratic function respectively， and the angle of internal friction increase slightly with the increase in the number of cycles. Both confining pressure and the number of dry and wet cycles have a great adverse effect on the progressive damage accumulation of red-bed mudstone. When the cycles are over 3 times， the damage variable value of samples under different working conditions generally exceeds 60%， the strength of the rock mass is greatly reduced.

Taking the flow and pressure regulating valve with piston sleeve of DN200 type as the research object， based on FLUENT and Realizable k-ε turbulence model， the three-dimensional flow characteristics in the valve with different opening are studied. The results show that there is a sudden change of pressure gradient at the orifice， and the pressure in the orifice firstly decreases and then gradually recovers from the inlet to the outlet. At the same time， there is a symmetrical circumfluence area near the wall of the downstream pipeline， and eddies of different strength appear in the valve. With the increase in opening， the vortex near the downstream pipe wall moves to the upstream， and the strength of vortex in the valve decreases gradually. In addition， a jet forms at the downstream of the orifice， and a “low-speed cavity area” appears at the center of the sleeve. With the increase in the opening， the maximum velocity in the orifice increases， and the jet extends to the downstream further. There is a high vorticity region with asymmetric distribution near the wall of the orifice， and the region with wall attached vortex is the potential location of cavitation. The linearity of flow characteristic is superior and the effect of energy dissipation and depressurization is obvious at small openings.

The structure of water use reflects the demand difference of water resources for regional economic and social development in a certain period. Based on the data of water use in Hainan Province from 2000 to 2016， this paper uses the theory of information entropy to analyze the spatiotemporal evolution characteristics of island water utilization structure in Hainan. The results show that， in the past 17 years， the information entropy of water utilization structure in Hainan Province is on the rise， and the stability and equilibrium of water use system are enhanced. The spatial evolution of water utilization structure shows significant regional differences. The information entropy value gradually increases from the central mountain areas to the surrounding coastal areas. The stability of water use structure system increases from the central mountain areas to the surrounding areas， especially to the north and south end， which is basically consistent with the unique topography， water resource endowment and economic and social development characteristics of Hainan Island.

Model tests are conducted to obtain the failure mode of the retaining wall with soilbags and the slip surface of the backfilled soil. Based on this， a velocity field is established. The angle of the slip surface is then solved using limit analysis upper bound method. Afterwards the slip angle is used to calculate the critical height of the wall and the earth pressure acting on the wall. The calculation results are verified by model test results， and it is found that the calculated critical height of retaining wall and the earth pressure behind the wall are basically consistent with the test results， which show that the calculated results using limit analysis upper bound method are reliable.

Because in some medium and small-scale hydropower stations， the runner blades of their hydro-generator sets often have cavitation， which affects the safe and reliable operation of hydropower units to a large extent. This paper starts from the problem of runner blades cavitation in a hydropower station. Firstly， the three-dimensional modeling of the Francis turbine is performed and then the full passage numerical simulation is carried out. Under different guide vane openings， the distribution of pressure and vapor volume on the runner blades surface are analyzed. It is found that with the increase in the head， the area of low pressure on the suction side of the blade expands further. Especially at 40 percent vane opening， the area of the low-pressure area of the suction side of the blade increases the most， and as the head continues to increase， the low-pressure area tends to move toward the middle of the blade. Meanwhile， the surface cavitation of the runner blade is greatly affected by the head under 40 percent vane opening. However， it is not greatly affected by the head under 100 percent vane opening. Meanwhile， as the opening of the vane increases， the surface of the blade becomes more prone to cavitation. The cavitation of the suction side of the blade which is near the lower ring is more obvious. The research results can provide a theoretical reference for the safe and stable operation of the hydro-generator units.

The structure and maintenance process of pumped storage units are complex. Based on digital technology， a digital maintenance platform is built for pumped storage units and realizing the hoisting and deducing of units are hot topics in the field of intelligent maintenance. In this paper， the digital lifting technology is put forward， and the lifting operation scheme of the unit is previewed by means of digitalization of the operation process and visualization of risk warning. Through the integration of multi-source data of the equipment with three-dimensional digital model， the two-dimensional lifting simulation service and spatial data analysis service are generated， and the digital maintenance lifting operation platform of the unit is built to realize the lifting operation simulation and two-dimensional and three-dimensional scene linkage. And risk identification makes the hoisting operation process have traceability and risk predictability， and assisting the decision of the best operation plan， improving the quality and efficiency of the maintenance operation of pumped storage units， has a good engineering application value.

In order to study the influence of filling method on the stability of cofferdam which has grain-containing clay on the inside and block stone on the outside based on the 1st earth-rock cofferdam of Yongning Water Conservancy Project， this paper firstly proposes the filling method of“block stone dike first， grain-containing clay follow-up” and determines the formula for calculating the intrusion distance of grain-containing clay according to the geometric relationship between the slope of block stone and the grain-containing clay and the follow-up distance. Secondly， based on the fluid-solid coupling theory， it studies the cofferdam working state influenced by seepage field and stress field under different drainage velocity of the foundation pit and combined ABAQUS with finite element strength reduction method to calculate the cofferdam in which grain-containing clay has intruded to the bottom of the dike. The results show that with the increase in reduction coefficients， the plastic zone develops from the bottom of the outside and gradually forms a penetrating plastic zone， and the maximum deformation appears at the bottom of the outside. The stability of the cofferdam is less influenced by the follow-up distance of grain-containing clay when it is more than or equal to the critical value of 16.22 m.When the follow-up distance is less than 16.22 m， the amount of grain-containing clay intrusion into the bottom of the dike is too large， which leads to the decrease in the bearing capacity of the cofferdam， and the stability of the cofferdam is threatened. In order to ensure the safety and stability of the cofferdam， it is recommended to control the follow-up distance of the grain-containing clay to be around 17 m.

Cascade reservoir operation optimization plays a vital role in improving water allocation and promoting hydropower system management. The Improved Kidney Algorithm （IKA） provides an effective approach to the cascade reservoir operation model. The Kidney Algorithm （KA） is a novel nature-inspired optimization algorithm as well as widely applied and approved owing to its fewer parameters， superior search efficiency and robustness. In this paper， the optimization mechanism of KA is presented. To overcome the drawbacks of low diversity in population and inferior convergence， scaling factor-based movement strategy and adaptive strategy are introduced to configure the IKA. The feasibility and effectiveness of IKA is tested by solving cascade reservoir operation model. The results point out that： the IKA could significantly increase the hydropower generation （320 million kWh） of the cascade reservoir by 4.03% and largely decrease the spilled water volume by 17.54% in comparison to the KA. Mmeanwhile， the integrated strategies could effectively conquer the prematurity of the standard KA algorithm as well as lift the population diversity and algorithm convergence.