Abstract:Based on the space-for-time method,the 1,4 and 8-year plant communities of abandoned cropland were selected to investigate infiltration process and characteristics using Disc infiltrometer(Z-700).One artificial community(Cargana korshinkii) and one natural community(Sophora davidii) were chosen as control.We found that:(1) stable infiltration rate under Sophora davidii communities was less than that under Cargana korshinkii communities.It may relate with soil perturbation and the higher root biomass of artificial Cargana korshinkii.(2) The average infiltration rate and saturated hydraulic conductivity of abandoned cropland were increased with theabandoned time.Soil saturated hydraulic conductivities(SHC) of 1,4 and 8-year abandoned croplands were 52%,74% and 98% of the SHC under nature Sophora davidii communities respectively,while stable infiltration rates of 1,4 and 8-year abandoned cropland were 57%,88% and 91%.It indicated that infiltration rate increased with plant restoration.(3) Soil infiltration characteristics were influenced by soil physical and chemical properties,such as soil porosity,bulk density,texture,compaction,moisture and organic matter content.With plant restoration,plant can generate a large amount of root.

Abstract:Canonical correlation analysis is used to analyze spatial heterogeneity and standing condition differentia of eight communities in early succession stage of abandoned arable land.Results show that spatial heterogeneities between communities are greater than those within communities.Spatial heterogeneities between communities have a positive relationship with most of standing condition differentia,both of which imply environments can act on community composition and structure of the early succession stage.Further canonical correlation analysis shows that environment differentia accounts for 49.6% of heterogeneities between communities.Heterogeneities between communities and nitrogen differentia show a strong positive relationship,which implies that nitrogen is the main factor acting on heterogeneities between communities.Besides nitrogen,soil phosphorus and potassium show a significant positive relationship,and therefore fertilizer,especially nitrogen should be fertilized in revegetated abandoned land.

Abstract:The purpose of this research was to estimate the response of surface soil organic carbon and soil nutrition to the combining actions of grazing and vegetation restoration.A grazed hillslope with four types of vegetation in the Majiasongpo catchment,Xichang,Sichuan Province was investigated to understand the effects of grazing on surface soil organic carbon(SOC),available nitrogen(N) and bulk density.The 0-5 cm surface soil samples at top,upper,middle and lower positions of the eroded hillslope were collected respectively.There were four treatments of tree-growth area,shrub-growth area,natural-grass re-growth area, and bareland at each slope position.Results show that surface SOC and available N are enhanced with restoration of vegetation.The improving effect of the vegetation ranks in the ascendant order of tree,grass and shrub.Grass and shrub can significantly improve the content of available N,while there is no significant difference found between tree and bare land.Differences in SOC and available N between slope positions are not significant.Treatments,in terms of increased soil bulk density,are shrub,tree,grass and bare land in turn.Significant difference exists between shrub and bare land,and there are no significant differences among other treatments.The response of surface soil to the combining actions is different.Surface SOC and available N are significantly decreased by grazing under the tree,while there are no significant influences under the shrub and grass.

Abstract:The biomass,soil characteristics and root distribution of 17-year-old pure Platycladus orientalis stand and Hippophae rhamnoides × Platycladus orientalis mixed stand were studied in Yongshou County,Shaanxi Province on the Loess Plateau.Results showed that mean height,diameter of breast hight and stand biomass in the mixed stand were 25.80%,36.88% and 128.23 % higher than those in the pure stand,respectively. Total biomass of each part in the mixed stand was higher than that in the pure stand.Compared with the pure stand,soil bulk density in the mixed stand was reduced.On the contrary,soil porosity,water capacity and moisture capacity were increased to a certain extent.Platycladus orientalis root system(diameter≤1 mm and 1～3 mm) in the pure stand was mainly distributed in the upper 60 cm of soil,yet those in the mixed stand were distributed more deeply and evenly.Distribution of Platycladus orientalis root system(diameter≥3 mm) in the mixed stand was close to that in the pure stand.Horizontal distribution area of Platycladus orientalis root(diameter≤1 mm and 1～3 mm) in the mixed stand was broader than that in the pure stand,while for root diameter greater than 3 mm,the distribution in the mixed stand was narrower than that in the pure stand.

Abstract:The mechanic characteristic of reinforced slope is analyzed by considering the coupling between fluid and solid of foundation,and the mechanism of the coupling is illuminated by Biot consolidation theory.Then thevariety of lateral displacements,settlements in the soil and the strain of reinforcement are compared by numerical calculation considering the coupling or not.Outcomes from the calculation are compared with obtained data of a test road.The conclusion is that the outcomes which consider the coupling are more consistent with the real circumstance.So,the coupling between fluid and solid of foundation should be considered as much as possible when analyzing the mechanic characteristic of reinforced slope henceforth.This can be used to guide practical reinforced slope engineering.

Abstract:A filed study on soil nutrient loss of different slope landuse types in the Xiaolangdi Gorges Reservoir area was conducted under simulated rainfall.Results showed that available K and NO3-1 content were higher in surface runoff in slope cropland and intercrop land between crop and forestry than those in fallow land,intercrop land between forest and grass and afforestation land.Nutrient content in surface runoff and sediment was highest in the beginning of surface runoff,and then became stable.There was an enrichment of different forms of nutrients in sediment.The value of enrichment ratio was between 1.01 and 1.43,and there was no significant difference in the value of the six landuse types.

Abstract:The N and P accumulation characteristics of soil in Songhuaba Reservoir are studied.Results show that the average content of total N of soil(0-20 cm) in the whole reservoir is 1.79 g/kg;NH₄-N,13.55 mg/kg;and NO₃-N,7.29 mg/kg.Landuses ranked from the high content of total N to the low are in turn the agricultural land,fruit land and vegetable land;NH₄-N,in turn the fruit land,agricultural land and vegetable land;and NO3-N,in turn the fruit land,vegetable land and agricultural land.The average content of total P of soil(0-20 cm)is 1.60 g/kg,and available phosphate,10.36 mg/kg.Landuses ranked from the high content of total P to the low are in turn the agricultural land,fruit land and vegetable land;available phosphate,in turn the vegetable land,agricultural land and fruit land.The content of total N in the rivers entering the reservoir is in the 2nd grade,but falls into the 5th grade near the reservoir.The content of total P of the rivers is in the 2nd grade,and the highest content of total P is in the 3rd grade.However,the water quality falls into the 3rd grade near the reservoir.

Abstract:Soil erosion,as one of the major global environmental concerns,is usually the result from both natural and human factors.Sediment in lakes and reservoirs can continuously record the history of soil erosion with a high resolution in drainage basins of those water bodies,and therefore analyses of it have been becoming an important approach of investigation of occurrence and persistence of soil erosion.Furthermore,an understanding of the process and mechanism of material migration within a lake-watershed system,interactions of lake evolution with human activities and their quantitative distinction is the focus of limnology.This paper reviews the development of applications of radioactive trace isotopes,magnetic minerals,particle size,carbon,nitrogen and other chemical elements of lake/reservoir sediment in soil erosion investigations,and elucidates their further utilizations and advances.

Abstract:Dianchi Lake has been listed as the focus of national river bodies harnessing,which attracts special attention in the conservation of the nine major plateau lakes in Yun'nan Province.Non-point source pollution is regarded as the primary cause of pollution of Dianchi Lake,whereas soil erosion,which accounts to 80% of the pollution amount,is the source of non-point source pollution. This paper introduced the integration of GIS with USLE,and usage of the spatial analysis of GIS and the algorithm of each factor of USLE to estimate the amount of soil erosion in the Baoxiang watershed.Results showed the annually averaged amount of soil erosion was 983.51 t/km²,which was in the category of low-grade erosion.The none or slightly eroded area occupied 91.5% of the watershed area,and contributed 52.80% sediment in watershed.The middle and the upwards eroded area only occupied 8.5% of the watershed area,but contributed 47.2% sediment.

Abstract:The information method principle was applied in the mathematical evaluation model of landslide erosion.The first step of it was to analyze the factors affecting landslide process,and determine the main factors by calculating and comparing their contributions to landslide erosion.After section division for the research region,the second step was to summarize the information of selected factors to reflect the degree of landslide erosion on each section,and then set up a quantitative evaluation model for landslide erosion,which was applied for landslide erosion evaluation in Tongchuan City.Results indicated that in the research region of 82.5 km²,the area of highly intensive erosion was 13.0 km², accounting for 15.76% of the total;the area of intensive erosion was 20.0 km², accounting for 21.24% of the total;the area of moderate erosion was 25.25 km²,accounting for 30.61% of the total;the area of light erosion was 6.0 km²,accounting for 7.27% of the total;and the area of slight erosion was 18.25 km²,accounting for 22.12% of the total.Thus the area of landslide erosion above middle class was 58.25 km²,accounting for 70.61% of the total area,which implies that landslide erosion in Tongchuan City is serious.

Abstract:Soil and Water Assessment Tool(SWAT) model is an advanced distributed hydrological model which is based on physics mechanism and integrated with Remote Sensing(RS),Geographic Information System(GIS) and Digital Elevation Model(DEM) techniques.In order to study temporal and spatial tendency of hydrological processes and find out a relationship among hydrological temporal and spatial process,meteorology and physiographic characteristics of river basin,yearly and monthly runoff simulations(1981-1985) were applied to Madao catchment located in the upper reaches of the Han River.After ascertaining the optimal parameters,satisfied simulation results were obtained with the accuracy of 0.9427 for Nash-Sutcliffe coefficient over the 5 year continuous monthly simulations on discharges,which suggest an excellent modeling performance of SWAT2000 in the study area.6 referenced sub-drainage basins were selected in the upper reaches of the Madao main river way,and topographic parameters were obtained using software of River Tools in each sub-drainage.Monthly runoff simulations were then applied to them with the same parameters as Madao catchment,the responses of runoff simulation to topographic parameters were studied,and the Normalization of Runoff-total Length Index(NRLI) were presented.Analyses indicate that NRLI is influenced by source density.NRLI fluctuates tempestuously as source density decreases sharply.Nevertheless,it still trends towards the constant 1 in Madao catchment.

Abstract:The research aimed at the anchor cable framework method for strengthening high side slope.Successful use of the design and construction techniques in practice has proved the method to be rational in economy and feasible in technology.In addition,the authors illustrate the validity of anchor cable framework in strengthening high side slope,and provide the credible experience for protection design and construction of high side slope.

Abstract:Based on runoff plot monitoring for different measures,the Sanchahe small watershed with the typical black earth in Binxian County,Heilongjiang Province was chosen as a research object.Six plots which include buffer strips,shrub barrier,contour cultivation,horizontal pit(planting tree in pit),denuded land and the ridge along slope were observed for two years.Results show that the amounts of soil erosion by horizontal pit,shrub barrier,contour cultivation,buffer strips,and the ridge along slope are reduced by 99.14%,97.65%,90.66%,87.7% and 58.72%,respectively,compared with denuded land.The horizontal pit is the best of all the soil and water conservation measures,whereas the ridge along slope is the worst.Runoff curve numbers are calculated for different soil utilizations.The study has provided a scientific basis for comprehensively preventing soil and water loss,choosing measures and protecting ecological environment in the future.

Abstract:Change of cultivated land is the core of land cover change,and also the change and its trend may reflect basic state of economy.Data obtained from statistical sources are used to analyze spatial and temporal change of cultivated land and driving forces by using relevance analysis,principal component analysis and regression analysis.The result indicates that besides total population and the amount of livestock,policy is also the dominant factor for change of cultivated land in Haiyan County.Countermeasures for sustainable use of land resources are discussed.The study will offer a reference to the protection of cultivated land in Haiyan County.

Abstract:Comprehensive evaluation of geological environment is important to urban environmental management and urban planning.Based on the systematic analysis of the chief factors influencing the urban geological environment in Xianyang City and the combined information diffusion with fuzzy integrated evaluation,a comprehensive evaluation model of geological environment was constructed,and then urban geological environment in Xianyang City was comprehensively evaluated.The evaluation model was propounded for regional geological environment by considering the effects of surrounding cells.In the model,the analytic hierarchy process(AHP) was used to found the influence factor weight.The fuzzy integrated evaluation was adopted to determine the effects of various factors on geological environment.

Abstract:The growth parameters such as height growth,diameter growth and the divaricates of the 2-year-old nursery stocks of Pinus edulis were analyzed, and different growth stages to height growth are determined by sequence cluster analysis.The result showed that height growth of the Pinus edulis was evidently characterized by the twice rapid growth stages.However,the considerable 5.64 cm increment of height growth occurs in the first rapid growth stage(April 11-June 30),and the increment at this stage accounts for 70.4% of the total increment in the whole year.It is the most important stage of fostering high quality nursery stocks of Pinus edulis.The diameter growth resembles and cooperates with the height growth.

Abstract:On the basis of the analyses of twenty year data observed in Jiuyuangou watershed on the Loess Plateau,a model of sediment yield of watershed under single rainfall is propounded through the application of back propagition artificial neural network.The network model is trained and predicted by input rainfall,average rainfall intensity,runoff depth and flood-peak modulus.The predicted results show that the network model has good precision and accurately reflects the laws of nonlinear sediment yield of watershed under single rainfall.It provides a new foundation to establish the predicted model of sediment yield of watershed under single rainfall on the Losses Plateau.

Abstract:The Yimeng mountainous area is the most serious area suffering from soil and water loss in the Huaihe basin.The occurrence and development of soil and water loss for a long time have formed the special erosion environment.The application of computer and GIS has brought enormous efficiency in soil erosion investigation and evaluation.Referring to remote sensing images and investigated data of soil erosion,the thesis sets up a soil erosion sensitivity appraisal system based on the universal soil loss equation(USLE).The appraisal system includes rainfall erosion,terrain factor,soil erodibility and vegetation cover,and each of the factors that influence soil erosion sensitivity is calculated using the GIS method.Then the thesis appraises the soil erosion sensitivity in the Yimeng mountainous area using the spatial method,and divides it into the extremely sensitive area,the highly sensitive area,the moderately sensitive area,the mildly sensitive area and the generally sensitive area.On this basis,the spatial distribution of soil erosion sensitivity is analyzed too.

Abstract:Based on the data of the Tarim River in 2003,the method of assessing virtual water was briefly introduced.Virtual water for the main primary farm products and total virtual water consumed by citizens were calculated.The results showed that virtual water for the main primary farm products in the region was lower as compared with other regions in Northwest China.In terms of total virtual water expenditure,there was no significant difference between urban and rural residents.However,for the consumptions such as food supply,pork,poultry,egg,cake,fish,there was a significant difference between urban and rural residents.The total amount of consumed virtual water was estimated to be 7.01×109 m³,and the total amount of the virtual water for production,2.20×1010 m³.This indicates that the total amount of virtual water for production is much more than that for consumption.

Abstract:In terms of the characteristics of water resource compound system and the conditions of water resources,an evaluation system of sustainable water resource utilization has been established according to the principles of sustainability.Projection pursuit model(PPM) and real coding based genetic algorithm(RGA) have been used in the evaluation,which can synthesize the multiple factors into a single pursuit value and attain an optimal scheme.The result shows that it is effective to solve the weighted human interference,and fulfill the evaluation of sustainable water resource utilization by an optimized sequence.

Abstract:To study the law of wind erosion on highway side slopes,the highway from Tongxin to Guyuan was selected as an experimental site.The average amount of wind soil in different side slopes was analyzed,and the law of wind erosion on different side slopes was studied based on wind erosion data of ten observation plots.Results showed that soil water content could evidently reduce soil loss by wind on side slope.The amount of soil loss on different side slopes was significantly different,and the amount of soil loss on the dumping ground without any measure adopted was greater than that on other slopes.Effect of hexagon brick was the best in preventing wind erosion,and the second was arch frame-saw.Effect of mechanical press was worst in preventing wind erosion.A correlation between wind erosion intension and wind speed was founded through analyses.Hexagon brick was more effective than arch frame-saw in lowering initial wind speed.

Abstract:Based on the RS images of Landsat TM in 1994 and Landsat ETM+ in 2002, information on landuse in different periods is extracted,and changes in landuse and landscape pattern of Pingdingshan City are studied.The main tendency of landuse change was that the areas of cultivated land and wood land decreased greatly,and however,the areas of urban land,industry and mining land and weed land increased greatly.The comprehensive landuse index decreased remarkably.Landscape structure and landscape heterogeneity also changed greatly,for patches density,diversity index,dominance index and the evenness increased.The largest patch index and the landscape shape index decreased.At last,the countermeasures for sustainable ecological development are brought forward.

Abstract:In order to improve water quality,it is essential to identify non-point source risk areas for pollution control when the point sources have been controlled.Modified USLE model was used to identify the risk areas of the Hangbu-Fengle watershed with the help of the spatial analysis tool of GIS.The risk maps were classified.Results show that the high risk areas are mainly distributed around the upper area of Longhekou reservoir.The upper and middle areas of Fengle watershed and the lower area of Hangbu watershed near Longhekou reservoir are critical for eutrophication of Chao Lake.The regions with the risk bigger than average cover less than 5.62% of the total watershed area,in which the agricultural landuse accounts for 86.47%.This indicates that agricultural landuse has higher risk.

Abstract:Jieliucun watershed in the hilly area of central Sichuan Basin was chosen as the typical study area.Based on field survey,geographic information system(GIS) software and Arc/Info,geographical database of the watershed,including digital elevation model(DEM),landuse,soil and vegetation,was built.The watershed was divided into some uniform grids(10 m×10 m) in accordance with the GIS's function of raster spatial analysis.Integrated with GIS,Universal Soil Loss Equation(USLE) was applied to predict the amount of soil erosion in the watershed after studying the reasonable method for calculating factor values of USLE.Results show that the annual average mount of soil erosion is 1 244.7 t/(km²·a),which is in the category of lightly eroded area.Sloping land covers 44.17% of the total area,but the amount of its soil erosion accounts for 77.93% of that in the watershed.The study demonstrates that sloping land is the major source of soil loss,and therefore rational sloping land use is the key to soil loss control.The case study of Jieliucun watershed indicates that the model is reliable compared with other related studies.

Abstract:The traditional descriptions of soil and water loss are mostly the definite approaches based on the current equation(USLE).In fact,soil erosion is an indefinite complicated process influenced by various factors and complicated border conditions.This paper aimed to study how to use GeoCA to simulate soil and water loss in terms of its principles,forms and processes.Moreover,sustained by GIS,the study paid a great attention to the rules and the dynamic microprocesses from one state to another in order to form the GeoCA-Soil Erosion system using the Von Neumann neighbor.As an example,the system was applied in Wanzhou district,Chongqing City,and the relations of soil erosion with the basic factors were analyzed.Results show that urban soil and water loss in Wanzhou district has been effectively controlled,At the same time,the process can be visualized with the integration of GIS and CA technology.

Abstract:It is a very important problem which quickly,correctly and objectively obtain the area of land use.With the remote technology,it is very easy to deal with this question,In this paper,according the feaure of remote sensing image and different kinds of something of land covers,a deep research on the classification of urban use based on remote sensing,finally some discussions are made for these methods.The results was compared to the manual interpretation and computer classification,this proposed new method has a number of anvanges over the conventional supervised classification method.

Abstract:By using species richness,Shannon-Wiener index,Simpson dominant index and Pielou evenness index,Species diversity study was made in the lands which converted from farmlands to forest or grassland for 3,4 and 5 years in Northwestern Shanxi Province.Research results showed that the species richness and biodiversity index was increased gradually,and the dominant index of them decreased with the elongation of rehabilitation in these converted land.Species diversity of these lands evidently increased.

Abstract:The theory of forestry health is applied to study the forestry health in Badaling Forest Farm.It is found that forestry health in the farm is affected by insect pest,forest fire,irrational forestry strand structure,low-level management in forestry,and drought and snow break.The unhealthy forest in the farm is estimated to be over 60 percent.The goal and principle of forestry health on conservation and instauration in the farm are brought forward.Five vegetation management models of forestry health of resuming of land,configuration regulation of low forest,ecological thinning intensity,target tree of approaching-nature and ecological remediation are presented.Based on the spatial database of project area,spatial database of 121 representative sample areas and minute sample areas as well as integrating particular pattern,the management pattern of 240 minute sample areas is established for the farm.

Abstract:With the construction of many hydro-projects in both the trunk stream and tributary the upper reaches of the Yangtze River,especially the Three Gorges Project and the South-to-North Water Diversion Project,and the implementation of converting farmland into forest and grass as well as soil and water conservation,sediment discharge into the sea in the Yangtze River is declining quickly.This reduces the silting rate of the Yangtze River Delta and might degenerate the Yangtze River Delta as well.Formation process of the Yangtze River Delta is discussed,and the impacts of upstream hydro-projects,rising sea level,land subsidence and human activities upon the Yangtze River Delta are analyzed.It is put forward that the coast reclamation which is still being carried on at present is an effective way to prevent the Yangtze River Delta from erosion.The result from the study has some guiding significance to the practice.

Abstract:The effects of soil and water conservation on surface runoff process in small watersheds of the Qinba mountainous region are analyzed by the parallel observation in two comparable watersheds.Comprehensive control of soil and water loss in the region can result in an increase in flood peak time by 30～60 min,and a decrease in runoff modulus by 25%～71%.Its effects are different for different rainfall intensities and rainfall amounts,and it decreases flood peak value by 14%～90%.It can also effectively retain precipitation in rainy season,and increase runoff in dry season.

Abstract:Soil erosion is an important factor that limits sustainable development in the Huaihe River basin.This paper analyzes the main influential factors that make ecology in the basin more vulnerable.Anisomeric topography and water system make the basin become basically vulnerable,while transitional geographical location makes the basin to be interactively vulnerable.Fluctuated precipitation and runoff also cause the Huaihe River to be vulnerable,and dynamical vegetation cover and the change in landuse are other factors that make the basin to be vulnerable.Historically,the Yellow River invaded the Huaihe River,which plays a significant role in soil erosion of the Huaihe River basin.Finally,the sustainable developing countermeasures to conserve soil and water are also presented for the Huaihe River basin.

Abstract:The Baiyangdian wetland is the biggest freshwater lake in North China. However,its ecological environment deteriorates seriously and the lake is drying up.This paper carefully analyses the present ecological environment state of the lake and the problems it faces,such as the decrease in water volume,deposition of mud and sand,decrease of biological diversity and increase of pollution,and an ecological restoration plan and specific protection measures are put forward.

Abstract:Mizhi County,as the part of the Loess Plateau of Northern Shaanxi Province,nowadays,its environmental conditions are not suitable for economy development and environment construction.So,it is essential to go in for further study of converting farmland to forest and grassland and eco-environment construction in the county.The paper aims to assess the achievements of converting farmland to forest and grassland and accelerate the course of eco-environment construction in the underdevelopment area.Some conclusions are drawn as follows.(1) Taking the program testing information in the county from 1998 to 2003 as a study object,and taking the social,economical and ecological situations before the program testing as contrasts,the paper gives an objective evaluation to comprehensive benefits in the county.Results show that the benefits of society,economy and ecology are all enhanced effectively.(2) Converting farmland to forest and grassland has significant influences on population distribution and landuse change.Among population and land resources,the total of agriculture labor,outworking labor and arable land change rapidly.(3) Influenced by converting farmland to forest and grass land,economical benefits in the county appear increasing step by step.General domestic product and forest product will grow notably along with the applying time of converting farmland to forest and grassland.Rural economics also increases significantly.(4) Rural economic growth is the most rapid among all of industries in the county.(5) Eco-environment benefits embody in soil and water conservation effectiveness.(6) The long time protecting mechanism must be set up in order to enforce the achievements of converting farmland to forest and grassland in the county.

Abstract:The Integrated Control Project of Soil and Water Loss in the Middle and Upper Reaches of the Yangtze River in Bijie area,Guizhou Province has been implemented since 1988.A total of 7 327.97 km² area is controlled due to project implementation. As a result,soil and water loss in the region has been kept effectively within a limit,environment has been improved evidently,integrated economic strength has been enhanced gradually,and poverty has been alleviated significantly.However,there are 4 problems which must be drawn a great attention.They are the project implementation unsuitable for the idea of people foremost,the special types such as soil and water loss control,the management and maintenance of soil and water conservation facilities,and the ecological crisis brought by coal use.The successful experiences from project implementation and the idea of people foremost must be insisted on.Soil and water conservation must be enhanced in views of overall development of national economy.According to the idea of people foremost,management polices and measures must be improved in a developmental viewpoint.

Abstract:Aerial seeding afforestation is an important approach to the restoration of vegetation in remote mountain areas of China.It is important to know aerial forest resources and key techniques for the study of ecological functions,developmental stages as well as forest management.Based on the 50 year history of aerial seeding afforestation and the characteristics of forest resource by aerial seeding,issues related to the management of the forest resource are discussed,and the measures and suggestions are presented.

Abstract:This paper analyzes the characteristics of water resources in an ecological residential district of a city.Recognizing the principle that water could recycle,the paper proposes that constructions of a collecting system of rain water,sewage and reuse of water in the middle management processes,and a management system can achieve water circulating usage in a district.Simultaneously,it is a useful approach to find new energy sources.Constructing such a district and strengthening water re-usage are not only a fundamental approach to solve the contradiction of water supplying to water demanding,but also a powerful safeguard for city ecological environment.

Abstract:Zhejiang Province is located in the red soil hills region of Southeast China.Soil and water loss is a major problem because of natural processes and human activities in the province.Based on the analyses of the situation,development tendency and soil erosion hazards,the important functions of soil and water conservation in maintaining ecology safety were investigated.These functions are increasing vegetation cover and soil penetration,increasing valid water,decreasing peak flow,reducing sediment in river and reservoir,improving water quality,exerting engineer benefits and preventing soil and water loss by human activities.In the same time,it also plays an important role in conserving environment and reducing soil erosion,as well as facilitating economic development in the undeveloped countryside.

Abstract:The theoretical basis and practical sources on the concept of optimum structure and disposition of soil and water conservation are discussed.Intension and extension of optimum structure and disposition of soil and water conservation are given.Researches on optimum structure and disposition of vegetation measures for soil and water conservation in China are summarized on the basis of practice.Basic theory and method of optimum structure and disposition of soil and water conservation is explained.

Abstract:Based on the present situation of desertification in Minqin County of Gansu Province,the causes of desertification in the region were analyzed in the light of both natural and anthropological factors.Based on the driving factors,some effective countermeasures are eventually proposed in order to control further desertification.These approaches included saving water and optimizing its allocation,implementing eco-migration and export of labor service,as well as highlighting scientific planning,stressing rational land utilization and establishing a better forest system for the purpose of protection.