Abstract:The big gestrainstorm in this century occured in Wulijimulun river watershed in Sev.-Sep., 1998, has caused serious flood and water logging disasters.Arter the flood,surveys and comparative analysis were carried out in two counties of Balinzuo and Alukeerqin by selecting the typical small watesheds.The results indicated that,in those better comprehensively controlled small watersheds,every practice had brought about the apparent effects upon water storage and soil conservation as well as flood prevention,thus reducing flood threats and dsmages caused by flood disasters.And at the same time,some suggestions for doing a better work on soil and water conservation are presented.

Abstract:The reasons for causing sediment stagnation in the northern reaches of the Yellow river have been analyzed.It is considered that the severe soil and water losses in the tributaries are the main reason for the sediment stagnation and the reduced volume of water flow from the upper reaches of the Yellow river made the sediment stagnation more serious in trunk stream of the Yellow river in the Inner Mongolia Autonomo us Region.The fatal impacts of the sediment stagnation on the national economy and social sustainable development are also described.Some countermeasures to harness a watershed with more sediment yield were presented by the analytical comparison between the harnessed watershed and the not harnessed one.These measures include:(1)turning passive prevention to active control of soil and water losses;(2) gathering the attention from all levels of the society to harness watersheds according to the market economy rule;(3) developing waterand sediment resources and changing side-effects to usefulness by means of the comprehensive and systematic measures;(4) regulating and controlling water and sediment status in view of the total reaches of the Yellow river.

Abstract:Through analy sis on root system,soil antiscour,antierosion and shear strength determination of slope protection plant on the Nenjiang dyke,the results show that,in a same section,soil antiscour and antierosion (water stablility)index and shear strength of surface soil layer are all larger than that of base soil layer.Plant root system has rather pow-erful strength of soil-fixation function,the antiscour index has clear coherence with root length and root quantity, the single cohere coeffcients are 0.9146 and 0.8197 respectively.Soil antierodibility is better and water-stable index are bigger as soil o rganic mat tercontent is higher,the cohere coefficient between them is 0.9132,the cohere coefficient of it with root lenght and root quantity are comparatively rather low,the single cohere coefficient are 0.8317 and 0.8091.Plant root quantity has a great bear ing upon soil stability,the cohere coefficient of it with shear strength is 0.9814.In the plants now available on Nenjiang dyke,the antierodibility of Carex duriuscula C.A.Mey is greatest,its soil-fix ation and dyke revetment and slope revetment function are most strong,so it should be given a energetic spread in the same areas.

Abstract:Naqu-Changdu highway line is located in north part of South-eastern Tibet Great Turner with EW direction,a great deal of landslide,collapses and debris flow deposits distribute due to extensive tectonic movements and frequent earthquake activties.All of these deposits are hazardous to reconst ruction and transportation of highway.Some new landslide,collapse,and debris flow disasters are tiggered by unreasonable cutting and digging activities.The main disastertypes in highway is intermitted collapse type landslide,multi-graded pulling type landslide,rainstorm debris flow,landslide type debris flow and glacial lake outbursttype debris flow.

Abstract:Rainfall erosion process can be divided into-different aspects,runoff washing and raindro pimpact,but their contribution to soil erosion can not be determined accurately under the condition of conventional rainfall simulation with single runoff plot.Relationships between rainfall erosion and runoff erosion and their contribution to soil erosion have been researched by using rainfall simulation with dual runoff plots.The research results show that under the same slope gradient and rainfall intensity,the sediment delivery in down-slope caused by runoff water from up-slope will increase with the increase of runoff water from up-slope.Under the condition of same slope steepness and runoff,sediment delivery caused by rainfall erosion is bigger than that caused by feeding runoff washing.Sediment delivery has increased by 50% when rainfall intensity increases 1 time. Sediment production caused by raindrop impact takes up 27.2%～45.8% of total rainfall erosion,contribution from raindrop impact to sediment production is affected by rainfall intensity and erosion pattern.

Abstract:Legume crops and pastures canfix large quantities of nitrogen(N₂) from the air if they are well pelletized and inoculated by the most effective strain of rhizobium bacteria.The principle and benefit of nitrogen fixation of legumes,and some other practical problems have been discussed.It is considered that the legumes inoculant technology is the key to control and improve degenerated grassland, and can promote the sustainable development of agricul-ture powerfully.

Abstract:Physically based on the green house and yield experiments,and advanced INAA(Instrument Neutron Activity Analysis) technique,the absorption and distribution characteristics of REE(Rare Earth Elements) in main crops of loess plateau are determined and analysed.All data determined provide basic material for the application of REE to agriculture.The important information that REE influence on crops is expected to obtain from the reseach results.These achievements provide scientific evidences for wide application of REE in loess plateau region.

Abstract:Gully density is an index to evaluate gully erosion and describe the sketch of gully erosion in a watershed.At present,some different approaches,such as grid approach and small spot number approach etc.,are used to investigate the gully density.However,there is no unique approach to be used by different investigators.Although these methods mentioned above can describe the existing condition of the gully erosion in a small watershed,it can not provide the antecedent information for the design of gully harnessing engineering.Nevertheless,the hydrological network approach,which can divide a large watershed into several sub-watersheds according to the gully characteristics,can give the same result of gully density in a watershed as the other approaches by combining investigation of engineering layout.Additionally,the basic data gained by using the hydrological network approach are in preparation for the later design of gully harnessing engineering,which can be used anytime.

Abstract:A indicator system of benefit evaluation to reflect economic and social develop-ment and ecological improvement is established.To evaluate benefit with fuzzy comprehen-sive evaluation and to set factor significance with analysis hierarchy process,it was realized that benefit evaluation was objective and reasonable.

Abstract:Based on analyses of the present situation of land reclamation in recenty ears,the economic development potentialities and the existing problems in the northeast of the Ulanbh desert area are presented.Then,some countermeasures are proposed for regional sustainable development.It is considered that only by using water resources properly can we guarantee the sustainable development in such a fragile region.

Abstract:By analysing ecological and economic benefits produced by adopted technical mea-sures during comprehensive managing experiment at Zhuanyao gull small watershed,the technical measures for effectively controlling soil and water loss in the area are found out,which provide a scientific base and practical methods for further developing soil and water conservation in northwest Shanxi province.