Abstract:Tne loess region of Gansu and Qinghai Provinces includes 40 counties of Gansu Prov, and 11 counties of Qinghai Province, In the region soil resources are destroyed frequently due to fierce wind erosion and desertification, affecting productive potential development.The improving measures are as follows,(1)to improve ecological environment for agriculture to construct farming soils with high potential，(2 )to increase investment for agriculture to improve productive conditions of agricultural soils;(3 )to integrate farming with protecting land so as to set fine ecological.system of agricultural land.

Abstract:To optimize structure of agriculture, forestry and animal husban dry of agricultural system and to predict their advances in the future，a dynamic simulation modelon the agricultural system in Tongwei county is developed according to the systematic dynamic theory by Forrester. Tongwei county located in hilly region of Loess Plateau is a poor region，thus it is important to adjust the internal composition of the agricultural system to raise agricultural productivity in the county. After the existent conditions and ,problems of the agricultural system in the county being diagnosed, the systematic network diagrams, including crop planting,forestry, animal husbandry, population, fund, etc. are made. The systermatic simulating equations，including 18 level ones, 32 rate ones, 126 auxiliary ones and 127 parameters, are programmed by maens of DYNAMO language. The simulating equation model with several feedback loop is able to function automatically and control artificially by personcomputer conversation in IBM PC/XT computer. Once the model is run, all optimination values and predicting values are expressed in diagram or table.

Abstract:The principle of system engineering is used to diagnose WhiteGrass Gully watershed systematically, and multiobjective planning mathematical model is constructed. The optimal solutions of model are obtained:when the objective function, that is, greatest pure economic income,least soil loss, minimum investment and maximum biomass, is contented。

Abstract:The main factors influencing development of agricultural economy in experimental area of soil and water conservation in Ansai county are population, soil and water conservation level, land area of agriculture, forertry,animal husbandry, and income from sideline occupations, etc. The total value of production each will increase steadily at the annual rate of 4.2% during 1986-2001,as GM (1, 1) forecasted, and is directly related to population, income from sideline accupation forest land area, soil and water conservation level,and animal husbandry land area，but negatively related to agricultural land area, as the analysis of the relativity shows. To maximize the total value of production of agricultural economy or the total average value of production each in the experimental areas, the productive forces must be improved, condition of sideline occupation be developed greatly, forest land area must not be less than 3000 of whole arable land，the agricultural land area should be about 25% of whole arable land, so as to optimize the production structure of agriculture, forest, animal husbandry,sidqline etc,

Abstract:Having harnessed comprehensively for years, Beizhuanghe watershed has changed greatly in biological environment and social features, soil loss and erosion have reduced obviously. The total pure incomes (TPI) are 183,800、201,000、317，500、 446,700 and 596,700 yuan respectively from 1981 to 1985. According to the GM(1，1)with grey system theory, it is predicted that the TPI during 1986-1990 will be 0.8212、1.1479、1,6046、2.2431,and 3.1356 million yuan respectively. The prediction results would be reliable and satisfying if no disastrous weather or unforseen inoutcome arised.

Abstract:In red loam region of Jiangxi Province, there is a dangerous trend to deteriorated development in ecological environment. There are natural disasters to varying degrees annually in the region, and generally, dry damages follow floods, resulting in heavy losses. The heavy losses of soil and water affect the development of agriculture, forestry, animal husbandry, sideline occupations and fishery. The counter measures to the conditions are, to formulate a correct guidelines in harnessing red loam,to develop forestry, animal husbandry, building materials, mining and procesing, to exploit resources in water energy, and to harness mountain,water, field, forest and road etc. comprehensively.

Abstract:The total area of the Poyang Lake region(including 11 towns and counties around lake)is close to 2 million hectares. The loss of soil and water becomes ever more serious, the ecological environment worse, and having an effect on construction of commodity grain bases, because of the influence of history, social and natural factors. The region includes Mt, land and high hill, low hill and hillock, hillock and plain, as well as zone of bank of lake. The control measures areas follows:(1 )to set a control system taking biological measures as the main, carrying out intensive farming,(2)to set a multiple system to be used repeatedly,(3)to set a system in technical service.

Abstract:Weathered granite areas are the important part of soil erosion in southeast China. In the corrupted area of weathered granite, two plots of natural slope were chosen in Tangbei small watershed. Having observed the rain capacity, rainfall intensity and the amount of soil erosion, we analyzed the three factors systematically, found the distributed law showing a curve with a double peak about the soil erosion every month in a year, and then set up a soil loss predict equation. It will present the scientific basis for the project of water conservancy, soil and water conservation and. agricultural capital construction with improvement and utilization of granite erosion in the same regions.

Abstract:This paper reviews representative slope steepness classification of FAO,Australia ,International Geographical Union Geomorphological Survey and Maping Council and Japanj small watershed slope map of 1950's yellow River soil and Water conservation survey team, and Zhu Xianmo's, Tang Keli,'s slope classification for soil erosion, and so on.We take the Wangdong watershed experiment area as an example of plateau area of leoss plateau, study the contribution of slope and discuss the classification, then, divided slope into 3 groups and 9 classes.