Abstract:The grievous gravitational erosion on Loess Plateau is the major ero- sion type of the region.The paper,with the quantitative geornorpholo- gical method,having analysed the topographical factor in gravitational erosion,raised the concept of topographical factor value,worked out the isograms of regional height facing vacancy for the area and the topogra- phy factor,proposed topographical index of gravitational erosion strength under different combining condition of lithology,it also explores the re- gional nature of gravitational erosion strength.

Abstract:This paper counted and analysed the number of counties affected bydebris flows and the county times of occurence for destructive debrisflows. The results are as follows, 1. in 29 provincial (municipal) administrative divisions of China, 771counties (cities) the debris flows occured in, among them Sichuan Pro-vince is the most; 2. there are 92 cities or towns above couny-level suffered from debrisflow disasters, nevertheless, Sichuan makes up 40% of the total; 3. according to statistical data (1901-1985), the destructive debrisflow occured for 18 county-times annually in China, but during the pe-riod of 1901-1950 for 10 and of 1951-1985 for 29. Sichuan is over 50% ofthe average. 4. based on the partial statistical data, the death number in annualaverage caused by debris flow was 117 and 179 before and after liberationrespectively; annual average number of houses destroyed were 60 and 1590before and after liberation. This paper discussed the debris flow harmsto factory, mine, highway, railway, course, military, hydropower sta-tion, irrigation and water conservancy, as well as tourist trade, etc.

Abstract:The observed data shows that the resistance of debris flow is higherthan that of water under the same hydraulic condition. According to theanalysis on different effects of coarse grains and fine grains for resistan-ce. This paper thinks that the reason causing increase of resistance ofdebris flow is the bed load in debris flow.In order to prove this idea, wehave analysed the relation between extra resistance causing bed load andincrement of resistance of debris flow. The result shows that the incre-ment of resistance increace with the extra resistance increasing.

Abstract:The critical rainfall lines of 35 debris flow gullies are discussed inthis paper.Their distribution laws are found out by the cluster analysis.According to the rainfall data observed at the debris flow gullies andpartial meteorological observatories or hydrometric stations,the author mo-unted the rainfall intensity and effective rainfall, then draw thechart. The critical rainfall lines of debris flow gullies are distributed inladder. Its tendency has no relation to the scale or the characters ofdebris flow and it is not either closed with the basin area, the length ofthe main gully, relative difference of height and average gradient ofmain gully beds, etc. .However, it has a close relation to the gradient ofslope in the formation region of debris flows and their occurence fre-quences. Especially, it has close relation to the forms of supplying solidmaterial for debris flows.

Abstract:Accoding to the debris flow development history, geological, geo-morphical and precipitation conditions,this experiment initially analysesthe distribution, cause and developing tendency of debris flows in Xihecounty. It is considered that the debris flows of this county distributesalong with structural beld with the changes of rock character and artificial destruction of vegetatin. Relying on these,the authors deduce the cau-ses of debris flows and discuss the forming of debris flows with relation totopography, the storage of solid materials, water supplies and new tectonicmovement. It at last draw the conclusion that the debris flows tend ofthis county will come into an expanding stage and become serious soon.

Abstract:By stratigraphic means, the paper makes division and comparison tothe geological sections from sedimentary bodies of debris flow in thelate pleistocene in Wudu, establishing synthetic geological columna sec-tions of the debris flow of this period,it also analyses the characteristicsof sedimentary facies in detail. The sedimentary bodies of debris flow inthe period are composed of mud flow facies, sheet flow facies, whichbear relationship on the action of debris flow, and alluvial facies andloess soil facies which have nothing to do with the action of the debrisflow.From this the paper deduces the forming environment of them, ex-plores the relationship among the occurence, ceasing, new tectonism andclimate of the debris flow, and then the action period of debris flow isdivided into four action phases.

Abstract:According to the geological and geomorphical characters, this paperexpounds and analyses the forms, types and causes of soil and water lossof Zhengning county in Gansu province in detail. It thinks that themain forms of soil and water loss in this county are hydraulic and gravi-tational erosions,hydraulic erosion is the leading one.The types of erosionrelates to the angle of hill slope, vegetation density, erosion modulus,strength and the sand discharge carried by water current keeping increasingfrom east to west in this county, the modulus of erosion increases fromless than 500t/km²·y in the east forest area to 600t/km²·y in the west.Based on above analysing, the authors deduce that the causes of soil andwater loss are the special landform with the deep cut gullies, the strati-graphic structure with soft rocks accompanied with hard rocks, the con-centrated rainfall, the active new tectonic movement and unreasonableexploring and utilizing by mankind, etc.

Abstract:The total river basin areas of Macao gully is 13.1km², the clear watersupply areas in upstream, the middle stream fault destructive belt areasand the down stream loess slide areas occupies 26%, 32% and 42% of totalbasin area respectively. It is a viscous debris flow gully which bursts fre-quently,the solid substances of debris flow mainly come from middle anddown stream. The sediment load carried to Beiyu river occupies about onequarter of Beiyu river, so at the mouth of the river it threatens Wuducounty town. Although the landslides of the down stream of this gullyare connected in a large sheet, the mean free face hight of side in thegully wall is only 1.1m, the highest is no more than 4.5 m,and the axisof the slideis more or less vertical with the gully trough. It is suitablefor taking the measure to construct dam holding buck slides, for thisreason 13 dams were designed for main gullies, testing in two years forflood and debris flow has demonstrated that seven of the dams built madegood resulss.

Abstract:The control projects of Luhuagou debris flow of Heishui county waschecked, accepted and assesed in provincial level in 1987. On the projectplanning "the principle is rational", "the planning is correct", "themeasures are appropriate" .On projects "the design is accurate","makinga new trial on structural form", "construction and management arerigorous", "quality is excellent" .The project was regarded as all-excellentproject controlling debris flow on province-level. The paper analysed the formative conditions of debris flow gully.Itcomprehensively related to the idea,principle,programme and measuresof the planning, introduced idea principle, standard and new structureof the designation.At last it discussed the construction,management andits effects, etc..

Abstract:This paper describes a new framework-type diversion canal. It wasfirst applied to debris flow control in Heishui county in Sichuan provin-ce. The characteristics of the structure are as follows: connecting thewall and bottom ribs with the foundation and top walls of the canal tomake up a framework. At the point of stress concentration between thewall and bottom of the wall of the canal, cast corners are used for rein-forcement. At the downstream of the bottom ribs, raising the bottom by30-50cm so as to retain a layer of debris flow for energy dissipation andbottom protection. Framework-type diversion canal for debris flow canprevent: 1) being scoured of canal bottom; 2) being undercut of canal walls; 3) damage to the stress concentration points between the wall andbottom of the canal. It also ensures the safty of canal, repair and management are easy.

Abstract:At first the paper introduces the meaning.and contents ofcomprehen-sive transforming of soil and water conservation, and points out thatthe landslides and debris flows in the loess plateau area are the essentialfactors to increase the soil and water loss. It combines the comprehensivecontrolling experience of typical small basin such as Jiuyuan gully, Luergully and Nanxiaohe gully, puts forward that the comprehensivecontrol-ling of landslide and debris flow is the fundamental measures.

Abstract:This paper describes an innovative steel structure and installations forscouring prevention adopted in the spillway of the debris flow controlproject in Luhua Ravine of Heishui county,Sichuan province. The struc-ture is designed as, at the joint of lateral bottom and air face downstream the spillway of check dam, a 8-rocm thick steel plate was used to make a steel part which extrends out 50cm from the downstream air faceand rises 10-15cm, welded on double threading steel bar 25mm in diame-ter, it was casted into a steel bar-reinforced stopper,No. 200 in 50cm,connected with the check dam as a whole. Check dams with a spillwaystructured in this way can retain a layer of debris flow and play a role ofenergy dissipation and cushioning. When the following debris flows cro-ss the dam, the external force of direct scouring, friction, impact andundercut exerted on the dam by debris flow would be transformed intothe inner stress of stone against stone and sand against sand inside deb-ris flow, thus protecting the dam outled from the damage by debris flowwhich would cause the destruction of the whole dam.

Abstract:Relying on the Sujiapin landslide of Huize county in Yunnan provin-ce, this paper analyses the landslide stability with the multiple orienta-tion concept. It summarizes the demonstration method of pushing forceof crosswise and lengthwise, deep and shallow layers, the principles ofselecting safety coefficient and the whole stability analysing on the basisof the control engineering practices of the landslide.

Abstract:This paper compares and studies the strahler integral value S, theinformation entropy valuq H and the shape index N of river gully longi-tudinal section in rectangle basin,considers N as the index of therectanglebasin geomorphy developing stage. At the same time, this paper utilizesthe information of the three rivers (Jinsha River, Lancangjiang Riverand Lujiang River) basin in the northwest of Yunnan, demonstrates theindexes above all,at last draws the information of the developing stagein the cause of eroding circle and the information of the stability inerosional basin.

Abstract:Based on the topography, geomorphic character, stratigraphic tex-ture,physical and machanic indexes of landslide soil of Nanta landslide inTongchuan city and the hydrogeological condition of landsliding areasinformation, etc., this paper analyses the causes of this landslide and app-raises the stability of landslide in detail. It is considered that this is arepeatedly sliding and large scale landslide, the main causes of its form-ing relates to the rock structure and natural factors. It is relatively sta-ble landslide containing unstable factors.

Abstract:This paper supplies the preliminary scheme and mould of a middle scaleslide-resising constructure experience system in the neccessarity of ournation's slide-resisting structure developing and demonstrates a kind ofstructure system for landslide slide-resisting structure testing and thecontents and orders of structure testing system.