Abstract:With artificial simulation rainfall tests,runoff processes on the bare loess slope are studied and the following results are obtained:(1) Runoff rate varied with rainfall course and could be described with logarithmic equations.Runoff rate didn't change until 10～15 min after rainfall began;(2)Slope gradient influenced runoff depth and could be described with parabola equations.The critical slope degree was about 25°,above which runoff rate changed its trend;(3) Generally runoff depth changed with slope length and their relations could be describedwith logarithmic equations and the critical length was 80 cm;(4)Rainfall intensity affected runoff depth much more greatly than slope gradient did and could be described with linear equations.The action of the latter was al2 most glossed over by that of the former;(5)The integrated impact of the three factors on runoff depth could be expressed using a plural linear function.Rainfall intensity showed much more influential on runoff depth than slope length and gradient.

Abstract:Soil erosion can result in land degradation and sediment deposition of a river,where soil erosion is connected with some natural factors and human activities.Using ArcView 3.2 and Arc/Info 8.1 as the work platform,relations between soil erosion and terrain slope,between soil erosion and land use/land cover,between soil erosion and soil types of Lancang river basin in Yunnan Province are analyzed according to the results of map layers intersection and statistics analyzing.Finally,soil erosion of 1 km wide buffers of river and road in the same area is also studied.

Abstract:Rainfall is the main dynamic factor that causes soil loss and rainfall erosivity,it shows the potential ability of the soil loss caused by rainfall.Estimating the rainfall erosivity accurately is significant to predict soil loss quantitatively and make soil and water conservation program.Guizhou Province,with serious soil erosion,isone of the typical regions whose ecological environment is very fragile.In order to estimate rainfall erosivity accurately and analyze the spatial distribution and temporal change of rainfall erosivity,a daily rainfall erosivity model was adopted to calculate the rainfall erosivity of Guizhou Province using daily rainfall data during 1951-2001 from 19 weather stations.The results indicate that rainfall erosivity show increasing trend during the last 50 years which indicates that the potential ability of the soil loss caused by rainfall increase in Guizhou Province.The seasonal distribution of annual average rainfall erosivity is centralized and the percentage of rainfall erosivity in summer is 68.48 %.The spatial distribution of rainfall erosivity shows decreasing trend from the south to the north.The center with the largest rainfall erosivity is located in the southwest and southeast regions in Guizhou Province,while the center with the smallest rainfall erosivity is located in the northwest regions.However,rainfall erosivity is influenced by rainfall amount and intensity,there are a lot of differences between the distribution of rainfall and rainfall erosivity.According to the seasonal changing character of rainfall erosivity of whether stations,three regions are classified in Guizhou Province.With the increase of longitude from the west to the east regions,the centralization degree in seasonal distribution of annual rainfall erosivity decreases.

Abstract:Based on the investigation of soil seed bank,the soil organic matter contents and soil mechanical composition in different parts of sand dunes,so2called windward side,leeward side and lowland of sand dune,also the windward side parts,leeward side and the intersection of sand2barrier separately,where the sandy grassland in seriously desertificated and installed with high-banded sand2barrier of different years (2～3 and 4～5 years).The mechanism of high-banded sand2barriers for controlling desertification of grassland are studied by comparing with the same kind of places without sand2barrier.The result shows that installation of high-banded sand-barrier in seriously desertificated grassland can intercept seeds in sandy-driving wind,enriching seed bank,increase the contents of soil organic matter,decrease the coarse sand particles,increase the contents of minute sand parts in soil particlesize composition.

Abstract:The effects of soil physical properties,such as texture,bulk density and particle-size on nutrient transport velocity are studied by one-dimensional saturated steady flow experiments.The results showed that the retardation factor R increased with the increase of the clay content.R increased as bulk density increased in the same soil.R also increased with particle2size at different treatments.The repellent nutrient broke through soil column more easily than the reactive nutrient.

Abstract:Water and soil loss is an important landforms evolution course.Based on the theory of landforms erosion circulation and DEM analysis used as the method in the research of valley landforms evolution,the period of landforms evolution of massif region in Yishusi Valley is divided into youth period and old period.The correlation of soil erosion potential danger and soil erosion intensity comprehensive index and landforms evolution period implies that both human activity and landforms evolution period are of importance in soil erosion.

Abstract:Information on erosive rainfall is key to predicting soil erosion.Average annual rainfall data from 231 weather stations were used to determine the spatial distribution of erosive rainfall.Daily rainfall and maximum 10 min intensity data from 17 weather stations were used to determine the seasonal distribution of erosive rainfall.Results showed that the erosivity of rainfall decreases from the southeast to the northwest of the Loess Plateau study region,with annual rainfall showing a similar pattern.From the 231 weather stations,the highest R value was more than 4000MJ?mm/( hm2.h.a),while the lowest was 327 MJ.mm/(hm².h.a).The percentage table of rainfall erosivity for a half month period was used to calculate soil erodibility and vegetation coverage factors.The seasonal distribution of erosive rainfall is very limited in the Loess Plateau.Of the 17 weather stations,the percentage of the sum of continual six-month erosive rainfall to annual erosive rainfall was from 66.9% to 96.4%.

Abstract:The wind erosion and soil nutrient change of the pipe engineering of transfer natural gas from the west to the east in the west section of Shaanxi Province are monitored and analyzed.It showed that the lengths of pipeline through agricultural land,forestry,grassland amount to 60.8%,22.6%,and 9.6% respectively.The pipe eng-ineering could increase the wind erosion and worsen the soil nutrient.The wind erosion in engineering area on the stable and sem-istable sandy land is as double or triple times as that on site without disturbance by construction.During construction,the soil organic matter,total nitrogen and total phosphorus in the surface soil decrease by 30% to 40%,and the soil moisture decrease by 25% to 35%.

Abstract:Through discussion on studying conclusion of ecological agriculture and developing character of eco-economy system under the practice of converting slop cropland to woodland or grassland in Wuqi County.The authors point out that the newly developing model of ecological agriculture of four developing chains and webs should be constructed according to its regional character.So that industry structure is reformed and optimized including construction of reforming farmland environments.In addition,some measures on restoration and rebuilding the agriculture ecological environment are suggested.

Abstract:A site of building is located in the Dagou drainage area,the upper reaches of Minjiang river,where the debris flow and flush flood often occur.The risk of the site bringing by,possibly,the debris flow and flush flood is analyzed from the aspects of the characteristics of the debris flow,flush flood and its embranchments,the scale of its breaking out,and the influence of flush flood character in the ravine brought by the debris flow of its embranchment.Then the site was divided into several sections by risk extent of the debris flow of its embranchment.The results show that the main body of the site lies in the no2hazard area,so the plan is feasible.

Abstract:The overall length of Shaanxi Province from West-to-East-Natural-Gas-Pipe-Project is 346.2 km.Due to the project construction,vegetation on the original land has been distroyed with a consequence of large quantity of deserted soil,dregs and remains.According to analysis,newly additional soil erosion amounts to 8354000 tons,of which deserted soil is up to 6800 000 tons,occupying 81.40 percent out of the total volumn,deserted dregs and remains is to up to 1553000 tons,occupying 18.59 percent of the total.Practical measures are supposed to be taken to controll soil erosion caused by the project constrution

Abstract:There is existing a problem which can be the best way to conserve the soil and water at flat gradient crop land.Is it the cross ridge or longitudinal ridge? we emphases on analyzing the pros,cons and evolution of both ridges,and research a low cost practice with its mechanical equipment.It is sautible for either cross ridge or longitudinal ridge.

Abstract:A preliminary study on sediment yields of small catchments is conducted by using pond and reservoir deposits in the Liuxi river basin of Nanchong City,in the Hilly Sichuan Basin.The average specific sediment yield of small catchments over the basin is 762t/(km²a),and the tendency of sediment yield increase with the catchment area increase is not apparent.However,the sediment delivery ratio in the basin should be much higher than the previously reported values of 0.10～0.27,and the soil erosion rate should be much less than the values of 3000～5000t/(km²·a) reported by the second state survey using the remote sensing method.

Abstract:Based on grid of DEM,we take the lower reaches of Weihe flood data as a basis,and combined with Virtual GIS module of ERDAS 8.5,to realize visualized simulation in 3D of nonfountainhead flood according to principle of fountainhead and non2fountainhead.We demonstrate elementary dynamic submerge course of flooding,so as to impel the departments concerned to attached great importances to flood control,and to provide academic foundation for governmental planning measure,therefore to exploit wider prospect for developing governing flood work further.

Abstract:The processes of making landuse maps are introduced in detail.The authors propose that legend design and algebraic overlay operations using temporal series landuse maps are key processes.The basic principles of map making are discussed as simple,practical,visual,expressive and standard.Using 1993 and 2000 Thematic Mapper(TM) images for the surrounding districts of Xiaolangdi Reservoir,the authors analyzed landuse changes and produced a map representing landuse changes from before the construction of the reservoir to after its completion.A transfer matrix of landuse changes is also presented and the results are discussed.

Abstract:Soil erosion risk was graded using results from an analysis of soil erosion characteristics based on Geographical Information System ARCGIS.The process of grading the potential danger of soil erosion and its spatial distribution is straightforward in ARCGIS.Firstly,soil erosion modulus is estimated using a water erosion model,and maps of soil density and soil horizon thickness are derived from detailed soil survey data.Then,the temporal character of soil loss is calculated using soil erosion modulus,soil thickness and soil density.Next,in line with Ministry of Water Resources.classification standards,the potential danger of soil erosion is divided into five grades and an index of soil erosion potential danger( SEPDI) is established.The SEPDI has been tested in a case study in Fengdu County in the Three Gorges area,with ARCGIS used to assess erosion potential distribution characteristics.

Abstract:Through locating experiment and verification analyses conducted in pilot research sites for mechanized terracing in Wuzhuangyuan plateau slopes of Xifeng District and Songpan gully sides in Zhengning County,Xifeng City,a simplified mathematic model of multiple varieties and non-lineal is concluded for planning bulldozer terracing,that satisfies four targets: the less consumption of labor force,less quantity of terrace edge,more convenient for mechanized farming,and stable terrace.An earth-labor value with relevant models is established for calculation,namely,work quantity and weighted average-quantity of earth transportation.The output has been extended throughout the 6 counties/city of the project area of Gansu Component of China Loess Plateau Watershed Rehabil-i tation Project I,and achieved good effects.

Abstract:The first county along the Yellow river? Maduo County is the key region of the state natural protective source regions of Yangtse,Lancang and Yellow River.Supervising the Eco-environmental Change based on RS methods in the frangible and sensitive regions with high altitude will not only benefit the study of the natural law of frangible ecosystem in the cold and high altitude area,but also provide the operable and scientifically decision-making foundation for the local government.Based on two phases of the newest satellite image data ( the 1990 and 2000) and field investigation,the eco-environmental evolution processes since 1980s were analyzed.Analyses and discussions were made aimed at the understanding of the trend and causes of eco-environmental changes in the regions over the last 20 years.T he causes responsible for the eco-environmental changes in the regions were explored in accordance with the natural element including climate,frozen earth and hydrological change and human activity.

Abstract:Changting county is the region in Fujian Province which most seriously affected by soil and water loss.Soil and water loss dynamics is studied with SPOT data of 2000 and 2003.It was observed that soil and water loss occurs mainly in the mid to low hill area around the center of Hetian town,and decreases rapidly to wards the mountains.Eighty-seven percent of soil and water loss occurs at elevations of 200 to 500 meters.Over the last 4 years,the area and intensity of soil and water loss has decreased,especially in Hetian town,but severe loss has diffused from around the center of the town to surrounding areas.The declining soil and water loss is caused form several years of sound management work,including vegetation protection.However,lack of soil and water conservation measures under current development and construction projects,and agriculture expansion into steeper areas,is generating new soil and water loss.The net effect is an ongoing,serious soil and water loss problem,which will continue to be difficult to manage.Thus,management measures must

Abstract:In Tarim river basin,the climate isextremely arid and the ecologic environment is fragile.We analyzed the main eco-environmental problems in this area,which are desertification,soil salinization,and vegetation degeneration.Building the ecology protection system of multi-level and all direction is the guarantee to improve the eco-environment in South Xinjing Region,and to realize the sustainable development of society and economy.

Abstract:The fragile environment of gobi desert was destroyed because of mining work.The modulus of gangue and dregs was 160000t/(km²#a).It is increased more about 800 times than the original surface.The work of soil and water conservation was very difficult after the fragile environment was destroyed.To protect the existing vegetation and the earth's surface is the best prevention and cure measures.The dregs must covered after the gangue storeroom was stop being used.

Abstract:Proceeding from national conditions of China,it is an only way to ensure the basic demand of social economic development and grain production that the middle-and-low-yielding fields are improved and utilized.The authores analysed and researched the distribution situation and soil characteristics of main middle-and-low-yielding fields according to the mountain area cultivated land resource state.Then the measures to improve and use all kinds of middle-and-low-yielding fields are proposed.

Abstract:According to related data and investigation after the disaster,we analyzed the background,process and situation of the disaster caused by extra rainstorm in July 14.It is concluded that landform and earth's surface structure in Fufeng county are useful to the formation and occurrence of strong convective weather in some areas,sustaining drought in the former period cumulated energy for the disaster,direct reasons causing the disaster are warm-moist air flow from southwest,cool whirlpool in high altitude and cold front passing Fufeng county in July 13 and 14,enhancement of dynamic of plateau form slope and the location of the county seat are important reasons causing county seat being center area of the rainstorm.The important factors causing the disaster also include that urban space is narrow and small,social economy is highly intensive in urban region,drainage system is jammed seriously and the thought preventing natural disaster pay more attention to fight droughts and look down upon flood disaster.Therefore,it should be on guard that catastrophe occurs in small region.The research and prevention of small region disaster should be intensified.

Abstract:The geological,topographical and ecological condition of the No.2 highway slope at Xiaowan hydropower station in Yunnan Province are analyzed.Then the experiences and lessonsof slope management at this location are summarized from an early stage in the development of the area.Drawing on theoretical knowledge of ecosystem restoration and engineering,and on information of slope protection and revegetation techniques,the plan on protection and revegetation for the No.2 highway slope at Xiaowan hydropower station is turned out.Preliminary evidence is presented to indicate the suitability of the plan.

Abstract:The Heihe River basin,an inland-flow catchment and a very important base for grain,vegetable and economic crops,is one of the most affected areas by human economic activities.The water and land resources over exploitation of the middle reaches lead to a serious ecological problem at downstream.This has already threatened the safety of ecosystem within the whole basin.T he problem is mainly showed as zero -flow appears frequently,lakes dried up,groundwater table declined,area of forest decreased,lawns degradation seriously,land deserted and sand storm harms aggravated,etc.These environmental problems have been noticed diffusely by the government and public.The measure of water saving and distribution retionalization which are implementing within the basin is one of the primary ways for its environment protection.Harmonious development among population,resources and environment basinwide is very significant to maintain the stabilization of the border area,promote the progress of the society,and implement the strategy of the great exploiture of Western China.

Abstract:Based on the perennial practice to participate constructing project of national experimental and demonstration areas of soil and water conservation and first-hand investigation,to aim at some problems encountered in the constructing process of experimental and demonstration of soil and water conservation in some regions,we have put forward some suggestions on the problems encountered in the construction of soil and water conservation demonstration area roundly and detailedly from 4 aspects such as target of the construction,to hold the principle,construction contents and management measures for further discussion and integrity.We also hope that these suggestions are enriched and improved in practice and will be formed to a standardized proposal for the utilization in demonstration area construction of soil and water conservation.

Abstract:The concept of"Ecological Defence"is advanced from the ecological construction practice in China,and has been used only for several years.However,there has not an agreed understanding in academic circle.This paper discussed the functions and characteristics of ”Ecological Defence”,based on its definition made by the authores in another paper.In the author's point of view,the function of ”Ecological Defence”is a kind of protecting effect to the human beings’living environment,which the eco2system of”Ecological Defence”produces in its evolving process.It represents in retarding and purifying of the eco-system of”Ecological Defence”on negative factors,and protecting and conserving on the positive factors.According to the aim of ecological construction,the function of”Ecological Defence”can be divided into purifying function,adjusting and retardarcing function,soil conserving function,water manipulating function and biodiversity conserving function.

Abstract:This article put forward four problems which are deserved to be discussed and clarified in research of urban soil and water loss.The first is that the concept of urban soil and water loss need urgently to be clarified;The second is the suitability that the universal soil loss equation when it is applied to researching urban soil and water loss;The third is that intensity classification of the urban soil and water loss;The fourth is that aspect and character of landforms shaped by constructing of the exploitation construction items.These questions are discussed the oretically,and individual unique viewpoints of the authors are put forward,appealing for strengthen theoretic study on urban soil and water loss.