Abstract:The large achievements of river harnessing are affirmed，but it is pointed out that many projecting questions relative to soil and water loss are still existing. Based on analysing the river harnessing from the view of dialectics, it is considerd that soil and water conservation is a basic measure of reducing flood and drought and an important measure of utilizing rationally and protecting water resources，and it is the basis of river harnessing.

Abstract:Based on many years research in loess plateau region，the quantity and quality of land resources，the current state and potentiality in future of food product and the trend of both popu-lation and food product growth are'discussed. It will be 0. 17hm²and 0.15hm² available cultivated land per person，so that the food product will be 2 520kg/hm² and 3 470kg/hm² in the year 2000 and 2010 separately. The natural rate of population growth will come up to the standard by our government and each person will have 400kg and 500kg food or more in the both years separate-ly,the conclusion is that loess plateau will feed its population fully in the future.

Abstract:Based on the observed data of runoff一sediment yield under more than 30 times individual rainfalls at about 4 diffrent grade gullies (Tuanshangou，Shejiagou，Liujiagou，Chabagou etc.)in 1963一1969，the basic features of the rainfall and gully runoff-sediment yield process in loess plateau region are statistically analyzed.

Abstract:Through the investigation at 170 sample plots of soil and water forest in limerock region of Taihang mountain and the analysis of 13 qualitative and quantitative factors in each sample plot, the soil and water conservation forests are ordinated by methods of principal component analysis (PCA). The results show as follows:(1)The four types are divided in hilly region under the altitude of 500 meters. They are in turn:arbor，shrub and herb mixed model of Plutycladus orientalis and Gleditsia microphylla with above 20shrub coverage，arbor，herb and shrub mixed model of Platycladus oriehtalis and Pennisetum flaccidum with under 1000 shrub coverage，shrub and herb mixed model of Vitex neguzulo var. heterophylla and Ziziphus ju juba with a little litter，and Pehnisetum flaccidum herb wasteland without litter. (2) The four types in low mountain region(500一800m)are:arbor，herb and shrub mixed model of Platycludus orientalis, Pinus tahulaeformis and Vitex negundo var. heterophylla with under 10 shrub covevage，shrub and herb mixed model of Vitex neguud var. heterophylla，cotircus coggygria var. cizzerea and Ziziphas ju juba with above 5000 shrub coverage，herb slopeland mod-e1 of Pennisetum flaccidu}n, Themeda triandra and Pennisetum flaccidu}n，with above lOcm soil depth，and arid waste land model with under lOcm soil depth. These divided types characteristics are manifest and difference among these types is significant by statistical test. The classification are recognized as justified with high accurecy according to Fisher test analysis. These results conform to practical state in the area. The arbor，herb and shrub mixed model is regarded as the best model of soil and water conservation forest.

Abstract:Qinwangchuan，being brought under cultivation in a large scale，is a area of higher erosion and margin of dryland farming in the process of improving dryland into irrigation farms with clearing away the grit cover，soil material to be apt to be eroded by wind makes up about 9000 of reclaimed surface soils. The fitful blast and combination of wind and temperature come into a stronger erosive force. Soil mass loss is 12. 24t/hm² per month from winter to the next ear1y summer，which results from the interaction of erosion and sediment. The change of wind erosion amount has no obviously relationship with wind speed，however the irrational human activities in irrigation and cultivation are the main factors of wind erosion.

Abstract:In semi一arid mountain area，soil erosion happens mostly on the cultivated slopland and results in poor harvest. Here，a model of having both ecological and economic effect is suggested to control and exploit the cultivated slopland. Water-control，surface-covering and intercropping are the main methods. The research suggests an effective space model about the plants (fruit trees and other crops)and water control methods according to different cultivated slopland.Through this technique 98.6%一99.10.surface runoff will be controlled and 93. 1;一95. 8%of soil erosion be reduced. The yield per unit area will increase respectively 64. 19%and 31. 21;than the control sloping areas with spring crops and areas covered by plastic film.

Abstract:"The soil moisture dynamics of potato field in southern Ningxia semi-arid area Is studied."rhe result shoals:(I)The moisture of potato field could be classed into three stages by thevariability，which very obviously cooperated with precipitation and its distribution within sea-(2)The soil moisture dynamics in vertical direction could he divided into three types too;(n)variable greatly layer <0～20cm). <13) slowly variable layer <20一120cm);(C) relativelyateady layer(120一200cm).The authors also analysed the moisture relationship among those three layer,.(3)In the period of duration of early harvested potato，consumed 3l2一394mm of water，it means 350mm，which mainly from irrigation or soil water in former stage and from rlin(all in its later stage. The ground film could save soil water and raising water use efficiency.and alum enhance riped earlier with high yield in the area，combined with cellar一harvesting wateru"e. We could develope local efficient agriculture, It is a reasonal technique way to increasing income for farmers.

Abstract:Wind erosion map delineation data in Songhua and I_iaohe river watershed are collected，and wind erosion laws are studied with linr}ar model theory. "the results show that the princi-pal factors to effect wind ersion are land use type and vegetation coverage. Wind erosion in every kind of sites in this watershed is predicted with the linear models established.

Abstract:Using the hight-analysis method founded by American geographer strahler A. N. ,the charactors of erosive geomorphy of Dacha gully have been quantitavely computed and analysed. This conclusion could provide a scientific base for the optimum arrangement and comprehesive harness in the area. For the present，the general harness degree reachs 94.40，soil erosion has been basically controlled，and 4 OOOm' of the runoff can be harvested，it improved the developement of water saving agriculture.

Abstract:The Qinghai lake watershed is located in the southeast part of the Qilian mountain in the Tibet plateau. In there, the topography is high，the climate is cold and dry，it is completely encircled by mountains, and the vegetation is good，it always is the fine natural pasture of Qing-hai province. However，since a long period of time，being effected by the disadvantageous .factors of nature and irrational social and economic activities of man一kind，the fragile ecologic environ-ment of the area steadily deteriorated，the wind-sand erosion are aggravated，the water is pollut-ed，the lake level droped，the prairie degenerated，the land becomes sandlized，the productivity is down，and the bird island exist in name only. All these have directly stricted the economic development of Qinghai province. In order to protect and improve the ecologic environment，and to make people rich up，the following measures are needed to be adopted:(1)To harness forest and grassland in the light of national laws;<2) According to the theory of ecological engineering，to plant trees and herb suited to local conditions;(3) To strengthen the management and use prairie rationally，so as to resume the vegetation and to lighten the wind erosion.

Abstract:Chaohe and Luanhe watershed is the key district of national conservation. In the period of "the Eighth Five-year Plan"，the experiment and demonstration for comprehensive harness of small watershed are conducted in Luanping county，the exploitive model which takes the har- ness of ecologic environment as a basis and the economic development as a object，is adopted. The concrete measures are as follows; to regulate the structure of plantation;to exploit waste mountainland vigorously，and to develop forestry and pomiculture;plant herb to raise animals，and to correctly handle the contradictions between forestry and animal husbandry. At the end of "the Eighth Five-year Plan"，the production of farming increased 2550 Yuan/hmz，forestry increased 1 300 Yuan/hmz，the erosive modulus reduced from 1646 t/(km². a) to 651 t/(km². a).Then，the obvious benefits of economics，ecology and socienty are obtained，so that the economic system keeps us a steady development.

Abstract:The main indexes of soil erodibility have been discussed. Soil erodibility is a relative concept，it is sugguested that the soil anti-erodibility and soil scourability should be separated in the study of soil erodibility. Soil has different erodibilities under the various forms and intensities of erosive force,so the condition of erosive force should be considered for selecting the indexes of soil erodibility.

Abstract:Israel is a typical example of water saving agriculture in the world. The characteristics of agriculture on water saving and its high efficient use in Israel are introduced，such as high water transport and water use rate，export of agriculture products for foreign exchanges, rain feeding agrculture,and exploit approaches of new water resources.