Abstract:According to the geometrics of ridge furrow,a formula for calculating the volume of individual shallow basin in various slopes was derived,and an optimum block space model was developed.This model suited various sloping fields. Through the examination on 2°,4° and 6° sloping fields with 3.6mm/min rainstorm by rainfall simulater in the ridge plots of optimum block space,they intercepted the rainfall of 54.8,50.4,and 42.0mm respectively,and were 18.4,19.9,19.7 and 49.4,44.6,39.9mm higher than that on the maximum block space and the open ridge respectively.Under the natural rainfall,the yield of soybean on 6° sloping field according to this model was 2 200 kg/ha,and was 22.3% and 36.8% higher than the check plots of the maximum block space and the open ridge.Therefore,the model is verified to be feasible and reliable.

Abstract:The crisscross region of water wind erosion is taken as the main research subjects,the relationship between soil erosion and eco environment change has been studied,the subjects and methods of monitoring research have been discussed.Using methods of typical field investigation combined with site dynamic observation,the characteristics of the climate and water wind erosion and eco envirionment evolution process have been analyzed.Through establishing series runoff plots and climate observatory,soil erosion process under varying landuses and topographical thypes in different conservation practices has been monitored,which includes the change of rainfall,runoff,infiltration and soil erosion amount;the evolution of rill erosion;the relationship between wind erosion and wind power;the evolution of soil erosion and soil degradation.The first observatory of water wind erosion and eco environment has been established in the fragile ecologic environment region of the loess plateau in Shenmu county.

Abstract:The natural and social survey and the current situation of soil and water conservation in northern Luohe river water shed are expounded.The necessity and possibility of harness and development at the area are analyzed.Then, the guiding ideology,the long-rang plan and some suggestions to the compr hensive harness and development are presented.

Abstract:Soil erosion has been acknowledged as one of the four major environmental pollutions. Loess plateau is the most serious region with soil erosion in China.The natural en vironment, the origin factors, the characters and the harmness to urban environment of urban soil erosion in loess plateau are discussed and the control measures are put forward.

Abstract:By taking a case study in Yuanmou hot dry vally, the economic,ecological and social returns of the model and conditions for the model have be analysed as follows:(1)The economic benefit is high,the economic inner return ratio(EIRR) is 47%～133%,the economic net present value (ENPV) is 300～700 Yuan, the economic benefit cost ratio (EBCR) is 3.74 ,the time of returns on investment is 4.08 years;The density of ground cover increased from less than 15% to 91.2%, the rate of erosion reduced by 98%,from 16 381t/(km².a)to less than 200t/(km 2.a).The flood damage to the farmer who lived beside the mouth of Ludouqing eroded gully and 108 highway eliminated;The high benfits of the model increase the confidence of exploitation and control of small watershed by famers and society. The model is an excellent example for reforming the control of small watershed.(2)The Benefit is high,loans can be repaid; The society is stable,the socialism market system and legal systems are being built and improved. The initiative,exploitation and controlling of eroded gully by interest free loans is high; The source of loans for exploitation and control of small watershed is stable and reliable ;There are enough scientific techniques helping the development of small watershed; The Administration is in order. According to the high economical returns of the model of exploitation and control of watershed and above conditions,a police and law of development and harness of small watershed by loans should be issued as quickly as possible by government and department responsible for the work,for adapting the deve lopment of socialism market economy.

Abstract:The studied area is located in the south marginal belt of the Qingzang Plateau where the tectonic movement is exctensive,the mountain uplifting and river undercutting region are quickly, inner the basin,the g radient of gullies are always 22～35°,the relative difference of height is 400～1 500m,these landscape conditons are advantageous to the formation of debris flow；nearly every extensive tectonic movenent,the quarternary glaciation,subglaciation and surfacial weathering generated many kinds of loose deposits and formed the solid material foundation for formation and development of debris flow；the annual precipitation is about 450mm, among which the rainfall during summer occupies nearly 90 percent,the rainfall during frequently ocurring period of debris flow in July and Augest occupied 60 percent of the annual precipitation,the 10 minutes rainfall intensity is 6. 2mm and 7. 6mm in Yang bajing and Lahsa respectively.The rainfall in studied area has the high intensity features of mountain area, in another word, the regional rainfall is quite favourable to formation and activity of debris flow.

Abstract:The development, distribution and classification of paleolandslide of Wangdong gully in Changwu county, Shaanxi province are mainly studied. According to typical investigation and systematical analysis, the result shows that it is the factors of geological structure, geomorphological forms,neotectonic stress fields, the movement of underground water and human being action that affect the development of modern landslide.

Abstract:The main achievements on soil erosion studies of ridge-hill-gully slope system in loess plateau are out lined. Based on the trends of studies in this field mentioned above,it is suggested that dynamic analysis should be taken as the key link, experimental simulation as the basic methed,time-space relationship between erosional forms, material and energy as the characteristics,thus bringing to light physical genesis of soil erosion in ridge-hill-gully slope system and providing scientific basis for soil and water conservation practice.

Abstract:Nuclear tracer as a new technique and method has been applicated in soil erosion studies,which makes the studies into a new period,and makes it possible to determine the source of sediment accuratly . The fast developing methods-¹³⁷ Cs,rare earth element(REE)and²¹⁰Pb tracer in soil eorsion studies were evaluated.

Abstract:Based on a host of facts,the harms of soil erosion and the function of soil and water conservation are analyzed positively and negatively. It is fully illustrated that soil and water conservation is the fundamental way to provent the drought and flood, improve the ecologic evironment and production conditions, accelerate the developing of national economy and the sustained and steady development of agriculture ,and shake off poverty and build up a fortune.It is emphasized that the key to do this job well depend on whether the the governments at all levels make great efforts to it ,and coordinate the departments concerned to make joint efforts;It also need to carry foward the spirit of relying mainly on self reliance while making national assistance subsidiary, strenthen the investment, make a thorough investigation of what they have got,and quicken the steps of harnessing and developing the “four wasteland”resource.

Abstract:The main functions of Internet and its application in China are expounded.Internet is applied mainly in communication and information servince,it includes E mail,Telnet,File Transfer Protocol and World Wide Web.Its application in information servince of soil and water conservation is also introduced.Some suggestions for developing the extant document resource and speeding up the progress of soil and water conservation information are put foward.

Abstract:The dry seed of red millet , a local strain of no rthern Shaanxi province, was irradiated with 300Gy⁶⁰ Co-gamma radiation, and a new st rain of Radioactive Millet 4 was bred out from genernation M₁₀.Thi s strain has the characteri stics of high yield, high quality and strong resistant to adversity.It has been spread on a area of 10.03 ha in loess plateau region,and good benefits of economy and society have been obtained.