It is of great reference value and practical significance to grasp the changing characteristics of spatial and temporal pattern of soil moisture for the comprehensive treatment of ecological environment and the prevention of soil and water loss. A SMOS soil moisture data downscaling method based on DEM correction TVDI was proposed to reduce the spatial scale of SMOS L3 soil moisture products with a spatial resolution of 25km to 1km, and the downscaling results were verified.Then, spatial root mean square error (RMSEδs) and temporal root mean square error (RMSEδt) of soil moisture changes were used to analyze the changing characteristics of spatial and temporal pattern of soil moisture in the research area in 2017. The results showed that the spatial and temporal distribution of soil moisture was not uniform, and the soil moisture content in south and east area was relatively high, while that in north and west area was relatively low. Soil moisture fluctuated with time and was generally higher during rainy season from June to August. In addition, the correlation analysis between the TRMM 3B43 precipitation data and the results of soil moisture downscaling data showed that different rainfall conditions would have significant differences in the correlation coefficient between soil moisture and rainfall.

Taking the average annual flow sequence of Changtan hydrological station in South China from 1961 to 2005 for 45 years as an example，this paper studies catastrophe point of hydrological sequence in Changtan Ｒeservoir by the cumulative anomaly method，Mann－ Kendall mutation analysis method ( MK method) and correlation analysis method． The results show that: ① from the beginning of the 1970s， there was an increasing trend of the annual average flow of Changtan Ｒeservoir，and it had a sudden increase from 1996 to 2001; ② the mutant point of hydrological sequence was in 1975，which was effected by both natural and human activities，and the main driver of mutations was climate change．

Ｒainfall is an important source of recharge for Jinan spring water，and plays a decisive role in spring water gushing． Based on the precipitation data of Jinan City from 1956 to 2017，the trend characteristics of annual precipitation in Jinan City were predicted by Ｒ/ S method and Mann－Kendall analysis，and the prediction results were applied to the groundwater management model of Jinan City． The results show that Jinan will be in a period of more precipitation in the future，mainly in the year of plentiful water． Ecological recharge plays an active role in the exploitation of karst groundwater in the water source area of Jinan City． From the economic point of view，the ecological supplement source has the problems of large water consumption，high cost and low utilization rate of groundwater． Therefore，it is recommended that no karst groundwater be added as much as possible． It can make use of the water supply from the reservoir during the flood season to replenish the river，and scientifically and rationally exploit the karst groundwater to meet the needs of the people of Jinan to drink high－quality groundwater．

Abstract: In order to explore a scientific and reasonable irrigation model and achieve the rational and effective use of brackish water in farmland irrigation, a field experiment was carried out in Zhanhua District, Shandong Province from 2015 to 2017. Four different irrigation treatments by using fresh water and brackish water with a salinity of 3.0g/L were established (T1:80mm fresh water + 80mm fresh water + 80mm fresh water; T2:80mm fresh water + 80mm fresh water; T3:80mm fresh water + 80mm brackish water + 80mm brackish water; T4:80mm fresh water + 80mm brackish water). The results showed that with the same volume of irrigation water, T3 not only could ensure the soil moisture, but also saved the freshwater resources. The final profit and loss of soil salinity was T1 < T3 < T2 < T4, indicating that T3 could ensure the appropriate soil moisture and accumulate less salt. The yield of T1 and T3 was increased by 10%~25% compared with the yield of T2 and T4. The yield of T3 was slightly reduced compared with T1. In terms of water saving significance and yield, the irrigation treatment of T3 was the better one.

Taking the main crops in Xinjiang planting industry as the research object, to study the temporal and spatial distribution of virtual water in main crops by using the Penman-Monteith formula,based on calculating the water demand ,virtual water of the main crops in Xinjiang from 2002 to 2016 is investigated. The results show that: the virtual water content of main crops showed a decreasing trend in time distribution, while the virtual water content (3.78 m3/kg) of cotton is the highest in the six crops, and the virtual water content (0.085 m3/kg) of sugar beet is the lowest,and the highest decline rate was wheat, which was 58.4%.The spatial distribution of crop virtual water content is obviously different, which is higher in the south than that in the north, and higher in the east than that in the west. In addition,there are big differences in the virtual water content of crops in different hydrological years. From the point of view of virtual water, Xinjiang, especially in the extremely dry and water-deficient areas of southern Xinjiang, water resources conditions should be first considered and lay out the crops with low water consumption and high added value to ensure the sustainable development of Xinjiang's economy and ecology.

In order to explore the mechanism of the effect of biodegradable film covering on farmland irrigation, the indoor soil column test was carried out to compare the water distribution before and after evaporation, the evaporation amount in different periods, and the temperature of different soil layers under common film and three different degradable films and without film covering conditions. A comparative study. The results showed that after the infiltration, the film was re-distributed for 48 h, and each treatment group could maintain water retention effect, effectively improve the soil moisture content of 15-25 cm underground, and BD2 treatment (type B complete biodegradable mulch film, thickness 0.010) Mm, the main component PBAT design degradation induction period 60d) is better than the other two degradable membranes, the film has a significant heat preservation effect on 5~15cm soil temperature. The film can inhibit the evaporation of soil water. The cumulative evaporation of each treatment after 192h increases regularly. The comparison of the three degradable membranes shows that BD2 treatment has obvious inhibition on water evaporation, and its water retention and heat preservation effect is not much different from ordinary film. The degradable film BD2 is optimally processed. This study can determine the law of soil moisture movement of one-dimensional soil column by degradable membrane covering, and provide reference for establishing related models.

Aiming at the lack of basis for the current first three irrigation method for cotton in southern Xinjiang, exploring the effects of different irrigation amount allocations on soil water-salt variation and cotton yield. This experiment was carried out with a fixed irrigation date, setting up three different irrigation quotas to investigate a suitable first three irrigation method in major producing areas of cotton in southern Xinjiang. After three irrigations, there was a certain divergence in the change of soil moisture content in different irrigation treatments, while the soil salinity increased, and the second water irrigation quota is positively correlated with the soil salinity increments. The decrease in first water irrigation quota resulted in late growth of cotton, but it is conducive to the increase of yield and irrigation water use efficiency. Reducing irrigation quota, the first-two water irrigation quotas are 420-600 m3?hm-2, and the irrigation date is June 15 and June 22, it can significantly reduce the accumulation of soil salinity and promote the increase of cotton yield, which is a relatively appropriate water irrigation strategy for cotton in southern Xinjiang.

This paper selects 5 water quality characteristic indexes of total nitrogen，ammonia nitrogen，nitrate nitrogen，total phosphorus and soluble phosphorus as evaluation factors，and then makes multi－layer target decomposition of farmland pollution reduction system by using mutation theory and fuzzy analysis，and finally constructs a theoretical evaluation model of farm non－point sources pollution control measures． Based on the experimental data from Qingshitan Irrigation Scheme of Guilin，Guangxi，this evaluation model is used to evaluate the effect of pollution reduction measures on four lines of defense，i．e． on－farm water－fertilizer regulation，farm－level ditches，constructed wetland and backbone ecological ditch． The evaluation results are in full agreement with the actual situation． Compared with the traditional evaluation method，this method avoids the errors caused by subjective reasons，so the evaluation results are objective and accurate． The method is worthy of popularization and application.

In order to study the effect of different sand mixing ratio on soil evaporation，a micro－infiltrator is used to measure the water evaporation in a field experiment． A complete test is adopted in the test，and two factors，rainfall and sand mixing ratio，are selected，and each of the five levels is treated． That is，five simulated rainfalls ( 6mm，9mm，12mm，15mm，18mm) and five kinds of sand mixing ratios are set ( 0%，25%，50%，75%，100%) soil evaporation test． The results show that the soil moisture content of the soil treated with the same sand mixing ratio increases slightly with the increase in simulated rainfall ( test irrigation amount) ，and the soil water content with different irrigation amount changes with the depth of the soil layer． Compared with bare soil，soil sand － covering can greatly reduce the evaporation of soil moisture． The sand mixing ratio is 25%，50%，75%，100% ( full sand) ． The soil is treated with bare soil ( sand mixture ratio is 0%) ． Cumulative evaporation has decreased by 5．4%，21．0%，36．2%，45．3%，respectively． The larger the sand mixing ratio，the smaller the daily evaporation and cumulative evaporation of the soil，and the sand mixing ratio of 100% is the best to suppress evaporation． It shows that sand and gravel covering can effectively inhibit the evaporation of soil moisture，and this inhibition is closely related to the sand mixing ratio． The research conclusions can provide a necessary guidance for the practice of sand and gravel cover in the arid regions of China， and provide data support for improving the efficient utilization and sustainable development of water resources in the sand control areas．

Aiming at the problems of the current irrigation and fertilization equipment，such as the dispersed assembly of various components，inconvenient selection of engineers，inconvenient use of operators，low degree of automation and low control accuracy，an integrated fertigation machine for small field with integrated irrigation，fertilization，filtration and automatic control in one device is designed． The response time and accuracy of the equipment under different pressure，flow rate and water－fertilizer ratio parameters are tested． Under the test conditions，the results show that，when the flow rate is 20 m3 / h，the set pressure is 0．1，0．2 and 0．3 MPa，the response time of the system to steady state is 13，15 and 18 s respectively; when the working pressure is 0．2 MPa，the set flow rate is 10，20 and 30 m3 / h，and the response time of the system to steady state is 12，15 and 18 s respectively; when the working pressure is 0．2 MPa and the flow rate is 20 m3 / h，the water－fertilizer ratio is set． Examples are 500 ∶ 1 and 100 ∶ 1． The response time of the system to steady state is 20 and 32 s． The equipment achieves full automatic control，fast response speed and high precision． It greatly simplifies the design and installation of the head equipment of the integrated water and fertilizer system，realizes the precise adjustment of water and fertilizer． The machine needs a low investment and has good application prospects．

Water lifting by solar photovoltaic system was an effective way to solve the energy in remote areas． The distribution of content provided of solar radiation，power generation and Water extraction were proposed，and the relationship between solar radiation，power generation and water yield were discussed． The research achievements can provide technical support for water irrigation energy issues for the Guangxi sugarcane producing areas of the solar application of sugarcane． 

In order to clarify the relationship between planting patterns, regulated deficit irrigation and light energy utilization to improve the production capacity of the intercropping system, taking intercropping of young Wolfberry and Alfalfa and only planting Alfalfa as the research object, setting adequate, mild, moderate and heavy water treatment. The photosynthetic characteristics alfalfa leaves and biomass of alfalfa were response to planting patterns and regulated deficit irrigation. The results showed that determine plant treatment, the AQY, Pnmax and LSP of alfalfa are increased, and the LCP and Rd of alfalfa are decreased with rising of irrigation lower limit. The Pn, Tr and Gs of alfalfa first rise and then fall with increasing light intensity. The Ci of alfalfa decreases with the increase of light intensity and then tends to be stable. The Pn, Tr, Gs and Ci of alfalfa decrease with the lowering of the irrigation lower limit, however, Ci is more than a moderately adjusted loss under heavy adjustment. With the lowering of the lower irrigation limit, the water content of the stolon and leave, ratio of stems and leaves, and the biomass of alfalfa decreased. In both planting modes, the aboveground biomass reached a maximum at full irrigation, with J1 being 513.84 g?m-2 and D1 being 518.84 g?m-2. Determine moisture treatment, each index of alfalfa under two cropping patterns are not significant differences. It showed that in the young plantation of Wolfberry Park, the wolfberry has no significant effect on the physiological and biochemical processes and aboveground biomass. Water is the main influencing factor of light energy utilization and production capacity under two planting patterns.

In order to explore the characteristics of precipitation and drought-flood in the Taizi River basin, the mathematical statistics method combined with GIS spatial analysis technology was used in this study. The precipitation anomaly percentage (Pa), standardized rainfall index (SPI), and long-cycle drought-flood abrupt alternation index (LDFAI) were selected to analyze the spatiotemporal evolution of precipitation and drought-flood based on the observed rainfall data of 19 rainfall stations from 1956–2006. The results showed that the precipitation has a non-significant decreasing trend, and the linear tendency rate is -12.96mm/10a. The distribution of precipitation also has an obvious spatial difference. The evolution of drought-flood in the Taizi River Basin has experienced four periods. There is a relative drought period since the 1990s and the frequency of drought is higher than flood. The drought-flood abrupt alternation events in the Taizi River Basin occur frequently and there is a significant difference of intensity in spatial distribution in typical years. In drought-flood abrupt alternation events, the number of flood-drought phenomenon is slightly greater than drought-flood phenomenon. The drought-flood events mostly occur in the lower reaches of the Taizi River Basin, it is necessary to focus on the impact of the drought-flood events.

Considering the limitation that univariate drought characteristics analysis cannot fully describe the nature of drought events，this paper takes Xixian watershed in the upper reaches of Huaihe Ｒiver as the study area． The meteorological drought index SPI is calculated by using the daily precipitation data of 42 rainfall stations from 1976 to 2016． The three drought characteristic variables of drought duration， drought intensity and drought intensity peak are extracted by run theory，and their two－dimensional and three－dimensional joint distributions are constructed based on four types of symmetric Archimedean Copula functions to deduce the combined return period． The results show that three－parameter gamma distribution fit the marginal distribution of drought duration best，while on the marginal distribution of drought intensity and drought peak intensity，three－parameter weibull distribution fit best． The Frank Copula function is best fitting for the joint distributions of two－dimensional and three－dimensional drought characteristic variables． It is estimated that in the combined return period， the joint return period can be the lower limit of the univariate return period under the same frequency and the co－occurrence return period can be the upper limit． The results can provide a reference for the drought prevention and disaster reduction in Huaihe Ｒiver Basin and for the analysis of drought characteristics in other basins．

Researches on evolution of drought play an important role in ensuring the safety of water resources and economic and social development. Nowadays, Copulas are used in the multivariate drought analysis considering duration and severity， but duration fitting methods could affect the results. In this paper, about 100-years-long monthly precipitation data of Beijing and Shanghai was used to compare parametric (exponential distribution) and nonparametric (run-length theory) fitting methods. The results indicate that these fitting methods are all reasonable, but non-parametric methods need extrapolation when dealing with extreme drought duration, so parameter methods are better in this case. The risk evaluated by using the run-length theory is always lower than the one using exponential distribution no matter which bivariate return period is used as the standard. For "and" and "or" return periods, the influences of duration fitting and severity fitting on the isolines are independent, whereas for conditional return periods, the effects are not independent.

The article comparative analysis the trend,abrupt change and periodicity of maximum flood discharge sequence from 1950 to 2016 in Minhe station of Huangshui basin control station,using the methods of Linear trend regression test, Kendall rank test, Spear man rank test, sliding T test, ordered clustering, rescaled range analysis(R/S analysis method), Mann-Kendall rank test and wavelet analysis. The results show that the annual maximum flood peak discharge at Minhe Station shows a significant downward trend. The year 2000 is a sudden change year. The variation characteristics of annual maximum flood peak discharge are controlled by the periodic fluctuation of four time scales (or the central scale of the period). Among them, the main period, which may exceed 32 years, is relatively evenly distributed in the entire time domain. Due to the change of the underlying surface and the implementation of water conservancy and soil and water conservation engineering measures, the water resources situation of the basin was changed directly or indirectly to a great extent, which led to the decrease of the measured flood peak flow and measured runoff in the Huangshui Basin

Channel confluences are common in natural rivers and hydraulic engineering, it has great significance to study the flow characteristic in open channel junctions for river regulation and urban water environment beautification. Thus numerical simulation which is based on Mike21 and validated by flume experiment is carried out to model open-channel confluence. And then, the flow characteristic variation under the condition of different discharge ratio and vegetation influence in a right-angled open-channel junction were systematically analyzed. The results show both the water level of main river upstream and the fluctuation of downstream increase with the increase of discharge ratio and it brings a deviation of the high velocity zone and increase of distance from low velocity zone to conjunction angle, and the velocity at the center of the separation zone decreases. To a confluence flow with vegetation, both the water level of the upstream and downstream increase, and it has a greater impact on the water level in the separation zone. Meanwhile, the distance from the starting position of the branch channel velocity deflection to conjunction angle increases. The research results can reference significance for development of irrigation and drainage engineering, urban environmental hydraulic engineering and ecological revetment .

Seepage stabilization and slope stability of type section of Xinji reservoir homogeneous earth dam were simulated using finite element method. Tree dam drainage designs, including well drainage within the dam, prism drainage at dam-toe and drainage on embankment slope, were studied under four typical unfavorable working conditions. The results indicated that three drainage schemes can meet the demands of seepage stabilization and slope stability, and the well drainage within the dam was optimal scheme, then prism drainage at dam-toe and drainage on embankment slope. Parametric sensitivity analysis of well drainage within the dam scheme showed that, after partial failure or complete failure, the safety factor of anti-slip stability of downstream dam slope were inferior to prism drainage at dam-toe. Based on comprehensive consideration of reliability of the structure, construction and stability of seepage and dam slope, prism drainage at dam-toe were recommended for Xinji reservoir homogeneous earth dam. The results of this study can provide a well reference for drainage design of homogeneous earth dam for small and medium-sized reservoirs.

To study the rough energy dissipation on the reduction of the energy flow process in curved spillway, using the method of model experiment combined with numerical simulation study of generalized spillway model, using water power dissipation rate, flow velocity uniformity, mainstream area as evaluation index of spillway flow improvement, the results showed that, the rough energy dissipation can reduce the flow energy, lower the downstream flow rate and increase the downstream water depth; rough energy dissipation makes cross section velocity evenly distributed and reduces the straight section adjustment distance at the outlet of the bend; rough energy dissipation can guide the mainstream area that is inclined to convex bank to the axis of spillway and restrain the shock wave propagation to the downstream straight section.

Monitoring data is an intuitive means to reflect the safety of the dam, and the accuracy of data sequence has a great impact on the safety evaluation and early warning. The traditional Pauta criterion for monitoring data gross error identification is only accurate for data sequences with specific distribution (normal or approximate normal distribution), while it is prone to miss out for sequences with more outliers. Accordingly, an improved Pauta criterion based on M-estimation was proposed. The control function is constructed by replacing the mean and standard deviation with the location M-estimator and the scale estimator based on location M-estimation, which effectively overcomes the problems that the accuracy of the traditional identification method is susceptible to the outliers and missing judgement of outliers. The improved Pauta criterion was applied to different types of monitoring sequences of the Gengda Hydropower Station. The application results show that the improved accuracy and applicability of the Pauta criterion based on the M-estimation is significantly improved compared with the traditional Pauta criterion.

Fractal theory is used to quantify the degree of fragmentation which is caused by compact energy． 4 kinds of compaction energy and 5 moisture contents are set to explore the change law of dry density under different energy loaded on grained soil by modified compaction tests． Then particle size distribution before and after compaction is obtained according to the particle sieving test． Characteristics of size fractal curves are analyzed and change laws of fractal dimension are summed up according to that distribution，which is applied to explain the micro －mechanism of particle breakage caused by external energy and moisture content． An analysis of test results shows that dry density reaches maximum when the moisture content is 8% in compaction tests of standard energy． Linear relationship of grain size fractal curves，the concentration degree of which is affected by moisture content，is significant with different compaction energy． The fractal dimension of grained soil decreases firstly and then increases with the increase in moisture content and the degree of particle breakage increases with the increase in compaction energy． Moisture contents change from 10% to 8% with the compaction energy increases under the condition that fractal dimension is minimized． It is suggested that the water content should be controlled and the compaction energy should be no less than the work of modified compaction standard tests during the compacted engineering process．

Inlet channel is an important component spillway, the flow state in it has an importane influence on the discharge capacity. Based on a bank spillway model of actual project, an experimental study on discharge capacity effected by type of guide wall, such as linear type, curve type and elliptic curve type,was procceed. The results show that guide wall closed to the dam play a very important role in flood process. When guide wall closed to dam was set, the flow state into the gate had been greatly improved,as well as the dischage capacity, because the lateral stream disappeared. And the longer the guide wall, the better the flow state. Thereinto, an elliptic curve guide wall with golden section ratio of long and short axes could adjust flow state and improve the discharge capacity most obviously.

In order to study the strength and microstructure characteristics of sandstones in the Paise Ｒiver，triaxial shear tests and CT scan tests were carried out for sandstones of different grain grades． The strength and microstructure characteristics of sandstone with different grain size were obtained． The results show that the strength of sandstone sample decreases with the increase in grain size in triaxial shear test． The two－dimensional and three－dimensional reconstruction images of sandstone samples were obtained by using CT scanning． It was found that the porosity and average pore radius of sandstone increased with the increase in particle size． The strength of sandstone had obvious“particle size effect”． With the particle size of sandstone becomes smaller，the number and sizes of pores decreases and the density of the sample become bigger． Therefore，the strength of the soft sandstone sample changes with the variation of particle sizes．

To study the applicability of the random forest intelligent algorithm to the prediction model of sand liquefaction prediction, based on comprehensive consideration of seismic factors, six factors including earthquake magnitude, depth of penetration, overburden pressure, cone resistance, normalized peak horizontal acceleration at ground surface and effective overburden pressure are selected as the evaluating indices to build the Seismic liquefaction discriminant model. Based on engineering examples, compared the results from random forest sand liquefaction discrimination model and normative method. The comparison results show that the random forest sand liquefaction discrimination model has high prediction accuracy and is a feasible new sand liquefaction discrimination method.

This paper takes Gaotang Lake as the research object then analyzes water quality． The water nutrition status is evaluated in the study area．The nutrient status index method and the comprehensive nutritional status index method are used to evaluate the nutritional status of the water in study area． Arcgis is used to generate eutrophication spatial distribution map in whole lake． Ｒesearch results show that ①Total phosphorus ( TP) is in inferior V water body，the concentration of CODMn in dry season ＞ flat water period ＞ abundant water period，the concentration of TN has little difference in different water stages，the concentration of Chla in wet season ＞ dry season ＞ flat water period， Transparency value in dry season ＞ flat water period ＞ high water period． ②The water is in a mild－moderate eutrophication level when evaluated by the nutritional status index method． Among them，the proportion of water in moderate eutrophication is 19．91%． Ｒegardless of the method used for eutrophication evaluation，the results in the wet and dry seasons are basically the same． ③When water body data is scarce，the concentration of Chla is not representative． The correlation between other factors and Chla concentration is not obvious． The nutritional status index method is used to evaluate the water eutrophication level results more realistically

Abstract: Oasis is a specific landscape in arid and semi-arid areas, which sustain the survival and development of human beings. The objectives of this paper is to build a suitable oasis scale mathematical model, combined with field investigation, historical statistical data, the characteristics of ecological environment and water quantity balance method and water and heat balance method, to evaluate the suitable development scale of Qiemo Oasis. The results showed that scale of oasis and cultivated land are 992.16 and 336.59 km2 in the Qiemo Oasis currently, respectively. A result obtained from the water quantity balance method indicates that the suitable scale of oasis and cultivated land are 1062.67 and 336.59 km2. The suitable scale of oasis and cultivated land less than the suitable scale, the oasis area of 70.51 km2 and the cultivated area of 185.71 km2 can be increased, and the area of the oasis can be expanded without being stability. A suitable oasis scale computation model obtained from water and heat balance indicates that the suitable oasis scale is 609.22-812.29 km2 and cultivated land is 92.66-123.55 km2. The existing oasis area and cultivated land larger than the suitable scale, which is beyond the size of suitable oasis and suitable cultivated land area of 0.2 and 0.6 times respectively. Therefore, oasis area should not be expanded. Through the relevant research and the actual situation in Qiemo oasis, the suitability index of oasis scale is 0.5358 in a metastable state, showing a trend of ecosystem degradation. It is need to pay more attention to oasis scale in order to maintain stability of oasis. The mathematical model for suitable oasis scale based on water and heat balance can be applied to evaluate the suitable scale of Qiemo oasis, which can provide a strategic decision for the sustainable utilization and management of water resources in Qiemo Oasis.

The variation characteristics of regional soil erosion is explored to provide the basis for the benefit evaluation of regional soil and water conservation and soil erosion control． Based on GIS and ＲS technology and by using rainfall data，DEM data，soil data and remote sensing image data，and ＲUSLE model，the spatial－temporal characteristics of soil erosion in Ji Ｒiver Demonstration Zone from 1997 to 2015 were quantitatively analyzed． The results showed that the soil erosion modulus of the four periods was 1 326．18，2 790．39，2 025． 23 and 1 366．32 t /( km2 ·a) ，respectively，the tendency was going from bad to worse at first and was then improving． Soil erosion was mainly micro erosion and slight erosion． Before 2005，soil erosion was transferred to higher erosion grade，and after 2005 to lower erosion grade． With the increase in slope，soil erosion tended to be serious first and then moderate． The slope of 15 ° ～ 45 °is the main slope section of soil erosion distribution in the study area． At different elevations，soil erosion increased first and then decreased with elevation． Soil erosion in middle altitude area ( 1 562 ～ 1 782 m) and middle－low altitude area ( 1 335 ～ 1 562 m) was the most widely distributed and the intensity was the largest． This kind of area is the key area of soil erosion control in Ji Ｒiver Demonstration Zone．

Baiyangdian is the study area. Taking GF-2 and the water quality parameters of sixteen monitoring points as the data source. Using maximum likelihood method, we can receive 8 kinds of land use types. The study utilizes spatial analysis to obtain buffers of 100m, 300m and 500m and obtains the area proportion of land use types. Pearson correlation analysis is used to explore the relationship. The results indicate that the pollution of TN in the study area is serious. The water and reed land are the main land use types. Instead, bare land and cultivated land occupy insignificant proportion of the area. Living land is an important local source of TP. Reed land can purify water quality. The water with more aquatic plants has significant correlation of COD, while water with less aquatic plants can dilute TP and TN. There is a possibility that NH3-N is contaminated by external sources.

The main issues to be solved in this paper are the comprehensive evaluation of the development level and the analysis of spatial pattern evolution of rural hydropower at the provincial level in China． Through the dimension of time and space，the development level evaluation indicator system was built from economy，society，ecological environment and resources fields ( 15 indicators) ． Based on the provincial panel data from 1990 to 2015，through entropy weight TOPSIS method and coupling coordination model，the development level of national，regional and provincial rural hydropower was calculated． On this base，the spatial pattern evolution of provincial rural hydropower was studied through cluster analysis． According to the cluster analysis results，the spatial pattern evolution of provincial rural hydropower can be divided into highly coordinated area，relative coordination area and poor coordination area． There are three main development periods of rural hydropower，namely: undulation development，unbalanced，uncoordinated development and steady development periods． On the basis of characteristics of provincial rural hydropower，some policy suggestions are put forward． 

In this study, three-dimensional numerical simulation was carried out for the flow characteristics of HLA351-LJ-275 turbine in the guide vane end clearance of Xiate Hydropower Station in Xinjiang under the condition of small flow rate, especially the cavitation flow.The results show that the pressure distribution in a single flow channel becomes uniform with the increase of the end clearance and the increase of the velocity at the clearance.In the process of gradually increasing the end face clearance from 0.5 to 1.5mm, the cavitation area increased and the bubble volume fraction increased.When the end face clearance is greater than 1.5mm, as the end face clearance further increases, the area over the active guide vane decreases, and the bubble volume fraction decreases.The cavitation erosion condition of guide vane end surface of 1.5mm is given through the test, the research results are of guiding significance for the design and installation of water guide mechanism of turbine in high?head hydropower station.

A new type of surge chamber called damped impedance surge chamber is proposed based on the structure of throttled surge chamber． The structure characteristics and operation principle of this damped impedance surge chamber are introduced． Hydraulic performance especially in surge fluctuation and water hammer of the traditional throttled surge chamber and this new damped impedance surge chamber are analyzed and compared by using an experimental model to test． Compared to the traditional throttled surge chamber，the experimental results show that this new damped impedance surge chamber will appropriately increase the water hammer pressure in penstock and reduce the amplitude greatly between maximum water level and minimum water level of surge chamber after load rejection，which makes the water fluctuation duration decline and shorter，reducing the height of designed surge chamber，improving the operation stability and save cost of the surge chamber．