Abstract:By taking the formation of mud-rain and dust-rain and other mud "granular fine sand",and the inlaying of fine mineral grain into coarse sand and other phynomena,as the sole characteristic for the formation of loess plateau caused only by the blowing and carrying of wind,and after checking each different periods'loess,which were formated for 2.5million years long,it was believed that the formation of the loess plateau was indeed the causes that the loess dust,which was carried by wind from west,met the moist airflow from east then continuously fell down then accumulated gradually,The loess layer accumulated this way,in which the structure appears frame touch,possessed fine aeration and permeability originally,later it is affected by the reproduction of vegetation,especially by the effect of root system of grass,the character is strengthened.This is the sole background and source for the accumulation of loess up to 100 meters and formulating the complete loess platcau--ancient soil under the natural condition.The soil and water loss violently,the main reason was human's destory on natural vegetation,thus it thoroughly destroyed the permeability and anti-souring of soil.So recent harnessing measures on loess plateau are forced to be"no-site-retain all precipitation"as the strategic goal,and adopt measures as "cereal crops are planted on plain and plateau land,forest and fruit tree are set on gullies,grass and shrub are located on hillside";and combining with the social and economic requirement,to arrange the reasonable land utilization and concrete productive measures.

Abstract:The surface erosion and fluvial silt in upper reaches of Changjiang River were analyzed systematically,It was considered that the development of surface erosion in upper Changjiang was affected by unreasonable social economic activities such as the agricultural cultivation,forest and prairie exploitation,roads building,and capital construction and so on which enlarges the area of soil and water loss in upper Changjiang River,The author also analyzed and forecasted that the erosion amount would reduce to 1.022 billion tons from present 1.568 billion tons in the end of this century based on recent steps.By regional forecasting the effect of surface erosion on fluvial silt,it was believed that the surface erosion could be reduced largely by harness tbe upper Changjiang River,but the fluvial silt may be not changed a lot,The silt amount of water carry will range from 0.488 to 0.502 billion tons at Yichangh,ydrometris station in 2000．

Abstract:A satisfied method for calculating sediment reduction bencfit in tomprehensive control of small watershed is not available at present.The difference of sediment delivery modulus before and after control is usually used to estimate the benefit,This paper pointed out that the sediment delivery modulus had a great variance as it's not reduced by synthetic control but by precipitation, and there was no Significated interrelation between sediment delivery modulus and characteristic value of precipitation etc, which brought about difficulty of benefit estimating,The author found that there was a closed relationship between Sediment delivery modulus and runoff rate,and the effect of preciptation on sediment modulus could be estimated by runoff rate, so that the sediment reduction benefit might be calculated accurately.

Abstract:This paper proposed that the anti erodibility of soil could be described by erosion ratio(erosion depth per unit runoff depth),and could also ba used to compare the different anti-erodibilitv of soil in different areas in a same period,or in the same area in different period,in order to monitor the influence of human's effection on soil erosion,for example,arbitrarily felling of trees,afforestation and soil and water conservation.By analyzing the tendency of soil erosion in the Hunnigang watershed vve found that to describe soil erosion with erosion ratio has many advantages.

Abstract:The middle part of loess plateau is a typical agricultural area,and the most significant property of agriculture in this area is that the hilly and slop land are opened up to increase crop production.Therefore,soil and water loss is the major problem to limit the economic development in this area due to unreasonable social economic activities.The factors affecting soil erosion by human activities were evaluated through the combination of typical investigation and analysis.The results of the destroy of vegetation and underestimating soil and water conservation works in industrial development are the main factors affecting soil erosion by human activities.

Abstract:By comparing the states of energy flow in agricultural eco-systems before and after adjusting the agricultural, forest, animal husbandry ratios, the comprehensive harness which takes the optimizing structure as the central task and lay stress on the putting matrial and energy into the eco-system were regarded as the effective steps to turn the agricultural eco-system from a vicious circle to a fine circle, and were also regarded as a main measure to solve the agricultural production problem in Loess Hilly Area.

Abstract:Based on the understanding of the intension of soil and water conser- vation,and the present situation of scientific research institutes of soil and water conservation in Fujian Province,the author took further steps to discuss how to improve the scientific research work of soil and water conservation in Fujian Province.

Abstract:Using grey theory with the data of annual curvy amount of water carry silt which gained from 1952 to 1985 for total 34 years at the emit mouth station (Zhang jiashan Station) of Jinghe watershed,the author establisped a group of grey models to analyze the ten years'benefit of decreasing silt during 1976 and 1985,This group of models was proved effect by checking the results with hydrological method,It presents a new method for calculating the benefit of decreasing silt and provide the basis for forecasting the soil and water loss in comprehensive harness in large values.

Abstract:The paper gives a brief ntroduction to the natural condition,the soil and water loss state and the agricultural production level before the harness of Fusheng watershed.It also summarizes the experieces and achievements in the aspects of planting grass and tree to increase vegetation,combining the biological measures with engineerings, constructing capital farmland,building road to develop trancportation,drawing out the managing measures and regulations for soil and water corservation,etc.in the comprehensive harness of soil and water loss,which is based on devlopment of agricultural production.The study investigate the muftiple benefits further in soil and water concervation,economy and society from the harness.

Abstract:According to the field survy and experimental research in loess hilly area southern Ningxia,the reasonable utilization and patterns of different shrub species were put forward.It provides the scientific basis for energetically developing and reasonable managing shrub forest,and also for making the most of the various ecological and economic benefit of shrub forest.Based on the natural environment and productive ways,three divisions were put out for fitting main shrub species habits.