The ecological environment is the core and foundation of the sustainable development of the district (stream) domain. And Yunnan is the water source area of the six major rivers in China. Its ecological environment is complex and diverse and highly fragile. On the basis of defining the concept of small watershed, this paper summarizes the natural geographical features of small watershed in Yunnan and the research status of its ecological environment. The results show that: at present, the ecological environment of Yunnan small watershed is 1) the research area is mainly concentrated in Dongchuan, and the research scope is single; 2) the research theme is mainly watershed hydrological effect, soil erosion and soil erosion, natural disturbance and ecological restoration and treatment. The overall situation is in the initial stage; 3) the content of each topic is mainly based on the description of phenomena and causes, and there is no corresponding countermeasure research; 4) The research techniques and means are mainly based on field observation and experiment, lacking models and multi-disciplinary means. Therefore, in addition to strengthening the above-mentioned deficiencies, future research should also focus on: 1) strengthening “local-to-integral-integrated” research; 2) improving observation techniques and methods; and 3) problems from ecological landscapes from the perspective of landscape configuration. Put forward targeted measures. Provide reference for the sustainable development of the ecological environment in the Yunnan Basin.

Based on Mike software, this paper constructs a one-dimensional hydrodynamic model of Pajiang Flood Storage, and calibrates and validates the model. By analyzing the flood encounters of the Beijiang river(Hengshi Station) and the Pajiagn river(Damiaoxia Station), the model is divided into two working conditions, namely the Beijiang River mainly and the Pajiagn river mainly. Comparing the calculation results of catchment area interpolation method and area proportion method, the results of the two methods are very close. The average difference is 0.9 cm of 5%, and the maximum difference is only 4 cm. It is recommended that the area proportion method be used to calculate the surface lines of other frequencies of the Pajiang River. The surface line of the Pajiang River can provide a basis for the operation and management of the Pajiang flood storage, as well as for the design of sluices, pumping stations and dikes.

The Irtysh River Valley Ecosystem is an important strategic water reserve area and an ecological barrier against natural disasters in Xinjiang. Affected by the construction of water conservancy projects, deforestation, overgrazing and other factors, the hydrological regime in the Irtysh River Basin has changed, causing problems such as the migration of migratory fish, the decline of forest and grass area, and the decline of biodiversity. In order to explore the relationship between hydrological regime change and ecological environment change, this study used the IHA-RVA method (Indicators of Hydrologic Alteration-Rang of Variability Approach) to evaluate the hydrological change degree of the BEJ hydrological station in the Irtysh River Basin. Studies have shown that the Irtysh Valley ecosystem is moderately altered and the following measures are recommended: (1) Ensure the demand for ecological water, and the ecological flow should follow the laws of natural abundance, flatness and dry season in the basin; (2) Arranging fish facilities and controlling the number of high and low flow pulse occurrences within a reasonable range; (3) Water conservancy project should cooperate with each other to carry out ecological flooding and dispatching from May to July, and timely replenish groundwater.

The characteristics of environmental factors in flood season are obvious, such as adequate nutrient and high temperature.In order to study the characteristics of algae species in Xiangxi Bay in flood season,the physical and chemical factors were monitored in the flood season of 2017, and the variation of chlorophyll-a and nutrients were analyzed. The results showed that chlorophyll-a was positively correlated with dissolved oxygen,water temperature, and chemical oxygen demand,and was negatively correlated with transparency, total nitrogen and nitrogen-phosphorus ratio, but had no correlation with total phosphorus and pH. In June, the dominant algae was Peridiniopsis which distributed in the upper and middle reaches, while the dominant algae in the downstream were mostly cyanobacteria and green algae.In July, the dominant algae was cyanobacteria, which almost covered the whole Xiangxi Bay. In August, the dominant algae changed into cyanobacteria and green algae, which mainly distributed in the upper and middle reaches.Water temperature was not the main factor affecting the outbreak of Peridiniopsis blooms;phosphorus and hydrodynamic would indirectly affect the growth of Peridiniopsis.Water temperature, hydrodynamics, pH and nutrients,especially nitrogen were all factors affecting the outbreak of cyanobacterial blooms. The environmental factors in August were still suitable for the growth of cyanobacteria one of the reasons why green algae became the dominant algae was the influence of ammonium,another reason was that some green algae produced harmful substance after death and decay, which inhibited the growth of other plants. In August, the chl.a concentration reached the threshold of the outbreak of green algae blooms.

In order to improve pollution reduction，this paper takes the Yuxi Ｒiver Basin ( within the territory of Yulin City) as the research object，uses the TMDL model to deal with the distribution of water pollution load by combining the single factor evaluation index model， simple load valuation model，and the deviation and mean square error method，and puts forward some pollution control measures based on the values of TMDL． The results show that the COD and ammonia nitrogen pollutants in Yuxi Ｒiver Basin are mainly from non－point source pollution，and reduce the pollution discharge of scattered livestock and poultry breeding． The model can reasonably improve the present situation of Yuxi Ｒiver water pollution，clarify the deficiency of prevention and control and the key points of improvement，and put forward reasonable suggestions．

The Jianjiang Ｒiver Alluvial Fan is one of the frontal alluvial fan clusters in the Longmen Mountains of Chengdu Plains． To study the content and spatial distribution of groundwater“three nitrogen”( NO－ 3 －N，NO－ 2 －N and NH+ 4 －N) ，feature descriptive statistics are used to analyze the content characteristics of“three nitrogens”，and the spatial distribution characteristics of NO－ 3 －N，NO－ 2 －N and NH+ 4 －N are plotted by ArcGIS spatial analysis function，and single factor and Bayesian water quality are applied． The evaluation method is carried out to evaluate the suitability of irrigation water for drinking water quality evaluation，sodium adsorption ratio，sodium percentage，magnesium hazard and permeability coefficient． The results show that the detection rate of groundwater“three nitrogens”in the study area is higher，and NO－ 3 －N pollution is the most prominent，and both had obvious spatial variability． The water quality evaluation results show that the groundwater meets the drinking water and agricultural irrigation water quality standards，but some water samples have the problem of total E． coli and nitrate exceeding the standard． The groundwater of the alluvial fan of the Minjiang Ｒiver has been polluted by“three nitrogens”，and human activities have a great impact on the quality of groundwater．

Groundwater is one of the important water sources for drinking，agricultural irrigation and industrial and mining． However，human activities have caused groundwater pollution problems． The current groundwater pollution problems have become one of the hot research topics in the field of water environmental protection． In the present studies，groundwater monitoring results of 195 monitoring wells in the Dongting Lake area are taken as research objects，and Fe，Mn，Cr and As are selected as water quality indicators． Based on the content characteristics and statistical analysis of the monitoring results，the inverse distance weighting method is used in ArcGIS to carry out spatial interpolation analysis，and the spatial distribution map of four water quality indicators is obtained． The results show that the order of element over－standard rate is: Mn＞Cr＞Fe＞As，the maximum excess multiple and the average excess multiple order are: Cr＞Mn＞Fe＞As． Fe pollution areas are mainly distributed in some areas of Nanxian，Anxiang，Qixian，Huarong，Hanshou and Dingcheng Districts． Mn pollution is mainly concentrated on the“four－port”river system，Xiang，Zi，Yuan，and Yi“four waters”and the surrounding area of Dongting Lake． The pollution of Cr is mainly concentrated on the surrounding areas of Nanxian，Anxiang，Hanshou，Dingcheng，Xiangyin and Miluo． As is mainly distributed in the areas of Lishui Delta，Minjiang Ｒiver and Xiangyin，there are scattered distributions in other areas．

This work investigates the runoff discharge pattern of pollutants，the event mean concentration ( EMC) and the first flush effect of three rainfall events in the period of August to September 2018． The results show that the roof runoff is seriously polluted in the early stage， with the extension of time the pollutant concentrations would gradually decrease，and finally tend to be stable． And the larger the rainfall intensity is，the more obvious the pollutant concentrations change． By comparing the EMC of various pollutants in three rainfall events with the fifth class value of the surface water quality standards and aesthetic environment use standards，COD concentrations in runoff are higher． The mean TP concentrations ( rainfall eventⅠand rainfall eventⅡ) reach esthetic environment use standard and become a potential energy source for lakes． The results provide data support for water quality evaluation of roof runoff and recycling of urban rainwater resources.

Based on the sediment of Bayin Ｒiver the effects of sulfides on the denitrification and denitrification efficiency of sediments in urban riverbed is investigated． The nitrification process has no obvious effect． The sulfide concentration of 50 mg /L can promote the autotrophic denitrification process，and the potential sulfur autotrophic denitrification rate ( PASAD ) averages 0． 014 meq/g VSS h． The dominant denitrifying bacteria of the mud are Thiobacillus，Thiobacillus and T． genus． The relative abundances of Thiobacillus and Thiobacillus are 25． 81% and 5． 82%，respectively． Under the control of carbon ratio，the average PASAD is 0． 011 meq/g VSS h，which significantly weakens the promotion of denitrification． The relative abundance of T． cerevisiae is 1．93%; the abundance ratio of dsrB gene is 0．115%，and the ratio of nirs abundance is 0．381%． The addition of carbon source is beneficial to the growth of sulfate－reducing bacteria， and provides a theoretical basis for solving the problem of low total nitrogen removal rate in black and odorous rivers．

Based on the daily precipitation data of 37 rainfall stations in the Beijiang Ｒiver basin from 1956 to 2016 and 6 extreme precipitation indices，the spatial －temporal variation characteristics of extreme precipitation events and the correlation with teleconnection patterns were analyzed by using the Mann－Kendall trend test，wavelet analysis and GEV． The result shows that the extreme precipitation indices in the Beijiang Ｒiver basin demonstrates non－significant increasing trends except the number of consecutive dry days ( CDD) in the past 61 years and mutation can be found during the end of 20th century to the beginning of 21st century． All indices have significant oscillation periods of 2 ～ 4 a． From the spatial distribution characteristics，the stations with increasing trend of extreme precipitation events are mostly concentrated in the middle and upper reaches of the river basin． The GEV distribution can better fit the extreme precipitation in the study area． The calculation results showes that the intensity and frequency of extreme precipitation in the Beijiang river basin have increased significantly in the past three decades，and the return period has great changes in the past and present under the same magnitude of extreme precipitation，and the extreme precipitation showing unsteady characteristics．

Abstract: The demarcation of river management scope in small watersheds with no data area is an important part of river and lake demarcation. However, due to the lack of measured hydrological data, the design flood level of river control sections cannot be derived from the relationship between water level and flow. This paper discusses the application of the inference formula method in the demarcation of river management scope in small watersheds with no data. It is considered that the method can accurately calculate the flood peak flow of each section design, and combine the measured section data to calculate the flood level from the flood peak flow. Finally, this method is applied to the demarcation of the river management scope of the Aojiahe small watershed. The calculated flood peak flow and flood level results are reasonable, and the management scope is successfully determined.

Combining theory with practice to synthetically determine the year of abrupt change in climatic characteristics. And based on the data of sunshine, temperature, wind speed and precipitation of the meteorological stations in the source region of the Yellow River before 2015, the correlation degree model of climatic characteristics in the source region of the Yellow River was constructed by using Rough Sets and Set Pair Analysis theory, and combines Mann-Kendall and R/S methods to explore the changing trend of climatic characteristics in the source region of the Yellow River. The results show that compared with the baseline period before 1990, the climate characteristics of the source area of the Yellow River have a trend of unstable development. Since the end of the 1990s, the implementation of protective measures for the source Region of the Yellow River has curbed the trend of deterioration, and the effect is obvious. However, the effect of changing the overall trend of deterioration in the source region of the Yellow River at the present stage is weak, and the Hurst index is 0.38. The system is counter-persistent, so it still needs a long time to change Time.

Selecting predictors (input variables) is the key for hydrological forecasting based on neural networks. Aiming at the problems that some existing methods cannot fully reflect the complex nonlinear relationship between predictors and predicted runoff and the information overlapping of the predictors can easily lead to overfitting of the forecasting model, a predictor screening method combining information entropy theory and principal component analysis is proposed and applied to the long-term runoff forecast of the Shiyang River Basin. The case study shows that the qualified rate of the long-term runoff forecast model based on the artificial neural networks in the Shiyang River Basin constructed by MI-PCA method is 91.67%, which is better than that based on the mutual information method (83.33%) or the principal component analysis (75.00%) alone. Therefore, The forecast accuracy meets the requirements of relevant standard specifications and can be used as a supporting model for long-term runoff forecast in the Shiyang River Basin.

Hangjin Banner has witnessed many explorations and practices in rational development，efficient utilization，effective protection and integrated management of water resources． Focus on ensuring efficient water saving in pastoral areas，water right transformation and agricultural water price reform in yellow river irrigation areas，practical work on industrial water saving，urban domestic water use，ecological environment control and drinking water security for people and livestock in rural and pastoral areas should be carried out． The construction of unconventional water utilization project，cultivation of market system for water trading has been strengthened． In view of the problems existing in the development and utilization of water resources，the strategy of high － efficiency utilization of water resources should be formulated scientifically． The most stringent water resources management system has been implemented，water resources and eco － environmental protection and scientific and technological support for water resources has also been strengthened． The efficient utilization of water resources has been achieved to support sustainable economic and social development．

Abstract: To study the impact of global climate change and large-scale reservoir construction and operation on the change of original precipitation characteristics in the Yangtze River Basin. The precipitation data in the upper reaches of the Yangtze River from 1961 to 2006 were collected and sorted out. The interannual variation, catastrophe analysis and spatial distribution characteristics of precipitation in the upper reaches of the Yangtze River were analyzed by linear regression, SPSS test and M-K test. The spatial isoline distribution map of precipitation in the study area was drawn by using GIS software. The results show that the average precipitation in Jinsha River basin and Yalong River basin shows an upward trend with different ranges, and the average precipitation in Minjiang River basin, Jialing River basin, Wujiang River basin and the upper Yangtze River basin shows a downward trend with different ranges; the distribution of catastrophe time of precipitation in the basin is dispersed; the average precipitation in the upper Yangtze River basin increases gradually from northwest to southeast, and in the Jinsha River basin. With Wudaoliang Station and Litang Station in Yalong River Basin as the center, the trend of annual average precipitation in the whole basin decreases gradually, while Leshan Station in Minjiang River Basin as the center, the trend of annual average precipitation in the whole basin increases gradually.

The rationality and balance of water use structures are prerequisites for the coordinated development of regional socio－economic development． Analyzing the temporal and spatial evolution of water use structure accurately can provide support for mitigating current water use contradictions and improving water allocation efficiency． On the basis of summarizing the spatial and temporal evolution of water structure， water structure driving factors and water structure prediction research status and methods，the shortcomings of current research and the development trend of future water structure research are proposed，which provides a reference for subsequent research．

The region of Beijing-Tianjin-Hebei is short of water resources, but the agricultural parks in the suburban areas of this region are flourishing. If water resources in these agricultural parks are efficiently utilized, more water will be saved and it is of great significance for alleviating the water supply contradiction in this region. On the basis of analyzing the present situation of supply and demand of water resources for the agricultural parks in Beijing-Tianjin-Hebei suburb areas, the connotation of high-efficient utilization of water resources in agricultural parks was given, and the evaluation indexes for the utilization efficiency of water resources in agricultural parks were filtered out. 3 criteria layers and 13 evaluation indexes were filtered out to evaluate the water resources utilization efficiency in agricultural parks. In this paper, the extension analytic hierarchy process is used to determine the index weights of each layer. The fuzzy comprehensive evaluation model is used to determine the membership degree of each indicator utilization efficiency. Finally, the water use efficiency of typical parks is evaluated by layer-by-layer calculation. The evaluation results showed that the comprehensive evaluation value for the year of 2015, 2016 and 2017 were respectively0.2987, 0.3965 and 0.6660, and the increase of the comprehensive evaluation value in theses 3 years gave a much better picture of the agricultural park's attempt in water saving irrigation, rainwater accumulation use. The evaluation method, evaluation indexes, and the weight of the evaluation indexes to water resources utilization efficiency for agricultural parks in Beijing-Tianjin-Hebei suburban area given in this paper achieved high accuracy and can provide references for the scientific evaluation to water resources utilization efficiency of agricultural parks in Beijing-Tianjin-Hebei suburban areas.

With the rapid development of economy and the rapid expansion of population, the problems of water resources shortage, water environmental pollution and water ecological deterioration are becoming more and more serious. Therefore, on the basis of coordinating regional socio-economic development and ecological environment protection, it is an effective way to alleviate water crisis and realize sustainable utilization of water resources to clarify the carrying limit and state of water resources. In this paper, the concept of load balance is discussed. By introducing the coordinated development degree, this paper measured the degree of balanced development of social economy and ecological environment. As a constraint condition, a multi-objective calculation model of water resources carrying capacity is constructed and applied to the Luanhe River Basin. The results show that with the passage of time, the water resources carrying status of Luanhe River Basin shows a general trend of improvement. However, the carrying status of Tangshan area in the basin is worse than other areas, which needs attention of relevant departments.

The shortage of water resources is becoming more and more serious in Urumqi，so it is particularly urgent to optimize the allocation of water resources． Ｒegional water resources allocation is successfully constructed based on the system dynamics theory． Low，medium and high water－saving schemes were worked out． Computer simulation analysis was conducted from 2017 to 2040 in Urumqi． The water shortage of low，medium and high water－saving schemes under the scenarios of multi－year average，high water year，high water year，high water year， normal water year and low water year were calculated，and a better scheme was chosen． It is concluded that Low water－saving schemes are not sustainable，maintaining the status quo of water resources and industrial development is difficult to ensure the demand of economic and social． Medium water－saving schemes are also not feasible． It is still difficult for water resources to meet the needs of economic and social development to properly improve the efficiency of water resources utilization and reduce the speed of population and industrial development． The high water－saving scheme is better． To further improve the utilization efficiency of water resources and reduce the speed of population and industrial development，we still need to increase the intensity of water diversion and the use of water，water resources to ensure the needs of economic and social development in a dry year．

This paper reveals the influence of flow field shape of irrigation ball valve on resistance coefficients and flow coefficients under different opening degree． The flow field of the ball value is displayed by numerical simulation． The steady water pressure of before and after value are measured by experiment． The numerical simulation adopted well with the experiment． The steady－state resistance coefficients and flow coefficients at different opening degree are calculated by CFD． The turbulence in ball valves from relatively small opening degree to large opening degree affects the local resistance coefficient and flow coefficients． The resistance coefficient and flow coefficient formulation of four kinds of ball valves are obtained by summarizing in test and simulation． This conclusion can provide a reference for saving－water agricultural pipe network hydraulic calculation．

The trend and distribution characteristics of water requirements of summer corn and weather factors in their growing season is discussed, and effect of climate change on ETc is analyzed according to weather data of 54 years for 9 weather stations in jinsha river dry-hot valleys Region (Yunnan province).Penman-Monteith formula was used to calculate the reference crop water requirement. The results showed that the monthly average reference crop evapotranspiration was 56.1mm-155.2mm. The annual variation of most stations showed a single-peak curve, while that of Qiaojia and Dongchuan showed a double-peak curve. The average water demand of summer maize during the whole growth period was 425.07mm, with a decreasing trend of 5.84mm/10a. Water deficit exists at different stages of maize growth, especially in the mid-growth stage. Yuanmou and Dongchuan had the largest water demand, Heqing and Yongsheng had the smallest water demand. Summer maize water demand at most stations showed a downward trend, among which Yongren, Yuanmou, Qiaojia and Dongchuan had a significant downward trend; sunshine reduction was the main factor affecting the downward trend of summer maize water demand.

Based on the weather information recorded from 1958 to 2015 by four meteorological stations in Nanning，Beihai，Yulin and Longzhou and the observation data in the cassava growth period from 2014 to 2015，the Penman－Monteith formula is used to calculate the water requirement of cassava in its each growth period． The effective rainfall empirical formula is used to calculate the effective precipitation in the main cassava production area． And the effective precipitation，cassava water requirement and cassava irrigation demand in different hydrological years are analyzed by P－Ⅲ distribution frequency calculation with frequency analysis． The results show that: the average water requirement of cassava growth period is 770．18 mm，and the water requirement in wet year ( P= 25%) ，in median year ( P = 50%) and in dry year ( P= 75%) are 704．91，758．88 and 866．05 mm respectively for the study area． The average annual cassava irrigation demand index ( IDI) for the study area is 0．14，and the cassava irrigation demands in the wet year ( P= 25%) ，in the median year ( P= 50%) and in the dry year ( P= 75%) are 0，0．17 and 0．39 respectively for the study area．

Abstract：In order to reveal the effects of biochar addition and irrigation mode on diurnal variation of soil respiration of paddy fields, diurnal variations of soil respiration rate of paddy fields under water-saving irrigation with different biochar addition rates were analyzed, and diurnal variations of soil respiration rate of paddy fields under different irrigation modes with biochar addition at a rate of 40 t?ha?1 were also analyzed based on field experiment. The results showed that diurnal variations of soil respiration rate of paddy fields during tillering stage, jointing-booting stage and milk stage all had several apices. With progress of rice growth, soil respiration rate of paddy fields under water-saving irrigation firstly increased and then decreased. Biochar addition increased soil respiration rate of paddy fields under water-saving irrigation, and the increasing effect of biochar addition at a rate of 40 t?ha?1 was better than those of the other treatments. The mean value of soil respiration rate of diurnal variation with biochar addition at a rate of 20 t?ha?1 and at a rate of 40 t?ha?1 were 2.85%~17.80% and 9.36%~30.58% higher than that without biochar addition, respectively. Apart from biochar addition, irrigation mode was also identified as an influencing factor. Controlled irrigation (CI) increased soil respiration rate of paddy fields compared with flooded irrigation (FI). The mean value of soil respiration rate of diurnal variation for CI was 2.03%~62.61% higher than that for FI. In addition, rangeability of diurnal variations of soil respiration rate of CI paddy fields was larger than that of FI paddy fields during three rice growth periods. The results of this paper can perfect theory of water-saving irrigation for paddy fields and provide a scientific basis for increasing carbonsequestration in paddy field ecosystem.

Through field trials. The regularity of soil moisture content, water consumption, LAI and yield of spring wheat under different irrigation quota and irrigation times was studied. The results showed that under the same irrigation quota, with the increase of irrigation times, the soil moisture content in the 0～40cm tillage layer increased successively, and the soil moisture content in the 40～100cm tillage layer decreased successively. LAI and yield of wheat showed 9 times > 7times > 5 times. Under the same irrigation number and different irrigation quota, the water consumption of wheat is shown as M400 > M350 > M300. Both LAI and yield increase first and then decrease, and the maximum is reached at the irrigation quota of 350mm. Compared with M350N7 and M350N5 treatments, LAI of wheat increased by 9.7% and 15.8%, and yield increased by 1.6% and 10.2%. The interaction effect of irrigation quota and irrigation times of micro-sprinkler irrigation on wheat yield was obvious. When irrigation quota was 350mm and irrigation times were 9 times, the yield and water utilization efficiency of spring wheat of micro-sprinkler irrigation reached the maximum (7943 kg/hm2, 1.96kg/m3).

The deformation and stability of the large artificial excavation slope on the left bank of Jinping I Hydropower Station are directly related to the normal operation of the hydropower station during the storage period and the operation period． In order to study the deformation response characteristics of the left bank slope after impoundment，this paper divides the left bank slope into three different deformation regions through an analysis of abundant geological data in the early stage，and then the deformation data of monitoring points in each region are collated and analyzed on the basis of the reservoir water level diachronic curve． The results show that there is a strong correlation between the continuous deformation of the left bank slope and the reservoir water level，but different deformation regions have their own characteristics． The deformation of the high－level toppling deformation area maintains a stable growth after an impoundment，and the curve of horizontal displacement and vertical displacement presents the characteristics of peak － valley correspondence． At present，although the deformation rate of monitoring points in each region is not very high，it still has not converged，and needs continuous monitoring and attention and further research．

At large unit discharges, low energy dissipation rate and cavitation damage are common problems in stepped spillway, and relevant studies have been conducted to address these issues by investigating the size and layout of the steps, with little focus on the step configurations. Therefore, the current paper aims to examine the effects of step configurations on the flow field, vortex structure, air concentration and pressure distribution by using Realizable k-? model for mixture flows. The simulated results suggested that 1) installing pool weirs can decrease the interfacial velocity and increase the vortex intensity; 2) the air concentrations for all cases presented S-shaped variations, but step modifications cannot improve the aeration performance compared with the traditional configuration; 3) the pressure distributions on the horizontal step surfaces of the configurations with pool weirs illustrated U-shaped variations, while the pressure distributions displayed S-shaped variations for the flat stepped models; installing pool weirs and upward inclining step faces can increase the pressures on the vertical surfaces, but downward inclining the steps increased the areas with negative pressures; 4) compared with the conventional model, the energy dissipation rate for pooled stepped spillway and upward inclined stepped spillway were respectively 10% and 6% higher, however, the case with downward inclined steps showed a 10% decrease.

By analyzing and studying the characteristics and movement rules of the slope flow and accurately simulating and predicting the confluence process of the slope flow, the scientific basis can be provided for the prevention and control of disastrous rainstorm floods in the region, the soil and water control in the basin and the construction of water conservancy projects. The multi-flow flow distribution algorithm is an improvement on the current simulation of rainstorm flood process, which cannot take into account the spatial variation of surface resistance in all directions. By simulating the spatial distribution of vegetation, it was segmented into segments, and the flow resistance was analyzed based on the flow characteristics of each segment. A hydraulic model test was established to study the difference in the flow resistance of slope flow in different directions. Conclusion: under the same water depth, the smaller the Angle of water flow through equidistant vegetation, the larger the water flow velocity, and vice versa. Under the same horizontal velocity of water flow, the smaller the Angle of water flow through equidistant vegetation, the larger the flow resistance, and vice versa.

Design and calculations of buttress of pressure pipes elbow curved downward are introduced in a variety of documents． It can be checked in the standard atlas and obtain the size of the buttress directly． However，the standard atlas has the following features: The atlas takes up a large space and the range of parameters is limited． When the actual parameters are outside the scope of the atlas the butt size can not be found． When the actual parameters are not equal to the parameters in the standard atlas，only the approximate value of the buttress size can be obtained and the error is large． The shape of the pier is not reasonable． Only the average base stress is checked without the unevenness of the base stress． But the former is not required to check and the latter is the key． No anti－overturn stability of the buttress is checked and there is no pier positioning size． This paper introduces the design and calculations of buttress of pressure pipes elbow curved downward． It overcomes the defects above and can directly solve the equation without a trial． The method in this paper is comprehensive，reasonable and simple．

The effects of four factors，such as water－cement ratio，aggregate particle size，slag content and silica fume content，on the effective porosity，plane porosity，average equivalent pore diameter，permeability coefficient and compressive strength of pervious concrete are studied by means of orthogonal test under the condition of 20% target porosity． The test results show that the water－cement ratio is the main significant factor affecting the permeability and strength of pervious concrete，and the aggregate particle size is the significant factor affecting the internal pore size． Water －cement ratio and aggregate particle size affect the physical and mechanical properties of pervious concrete by affecting the pore size distribution and pore size． The image method can better characterize the plane pore structure of pervious concrete．

In this paper, the transient analysis type of FEM is applied to imitate the pouring process of side slope concrete in the plunge pool of Wudongde hydropower station. The effects on the temperature and termal stress are compared under the solar radiation is taken in account or not. The results indicate that insulation measures are obliged to be taken to deal with the adverse impacts on the surface pulling stress of early-age concrete structures caused by solar radiation.

During the design and construction stage of hydro-engineering project, the drainage hole curtain is a vital seepage control measure. The accuracy of the numerical simulation process has a direct impact on the design and safety of the project. In this paper, drainage holes are simulated by the rod element which get widely used in engineering practice combing with the elliptic Signorini-type variational inequality finite element method. The calculated results based on several simple seepage cases and an example of Xiaowan project are compared and analyzed. It’s shown that: 1. The cone of depression is formed around the drainage holes and the simulated drainage holes in this paper are effective in water draining and pressure releasing; 2. In the seepage cases, compared with the results of the same process of the air element method, the suggested method has better accuracy; 3. In the example of Xiaowan project, the deviation of seepage field calculated results is small compared with the monitoring data of project, which also demonstrates the reliability and veracity of the this method. It provides a feasible solution to solve the three-dimensional seepage problem of rock and soil with complex drainage structure.

A structural reliability analysis method based on monitoring data and non － intrusive stochastic finite element method is put forward，and it is applied to the structural reliability analysis of gravity dams． Before solving the structural reliability，the mean values of stochastic variables can be obtained by the back analysis using monitoring data，which can reflect the performance of structures．

In view of the existing problems of reservoir management model in Jiangxi Province，the calculation method of dam vulnerability is introduced in detail，the construction principle of dam risk index system is put forward，and the index system of dam risk index is constructed． Based on four earth－rock dams in Dayu County，the risk index of reservoir group is calculated． According to the distribution of risk indices at all levels，engineering defects are still the main risks at present，while management defects are relatively weak． Based on the ranking of risk indices at four levels，targeted risk prevention and control measures and suggestions are put forward． This paper provides technical methods for improving reservoir risk management level．