Abstract:Based on natural precipitation observations,impacts of different types of land use on processes of soil and water loss over purple soil related slopeland were studied by simulated rainfall experiments.Measurement data revealed that rainstorms and slope length are the essential factors accountable for soil and water loss on purple soil slopeland for intense rill erosion can be caused on 10 meter long purple soil slopes by high intensity rainfall.Under circumstances of rainstorms,annual hedge plants grown on 25°slopeland can cause a reduction of runoff by 22～43 percent and that of erosion induced sand content by 94～98 percent. Stone bunded horizontal terraces can lead to a runoff reduction by 62～67 percent in comparison with steep slopelands and that of erosion induced sediment by 97.8～99 percent.Soil and water loss can be substantially decreased on steep slopes by hedge plants with a cost of only 10～20 percent of that of the steep bunded horizontal terraces.Hence it is an effective way to control soil and water loss in terms of slopeland amelioration and utilization in the Three Gorges reservoir area

Abstract:Horizontal diffussion cells were used to observe and measure the diffussion processes of the water soluable salt cations in engineering loess.The results obtained showed that the diffussion characteristics of every cation changed with its variety.The diffussion coefficient of Ca²⁺was the highest,and that of Mg²⁺, Na⁺ and K⁺ dropped in turn.The mean values of them determined in the two models were 2.692 8×10^-6,2.312 7×10^-6,1.6370×10^-6 and 0.4504×10^-6cm²/s respectively.The significant increase of the exchangeable K⁺, Na⁺ and Mg²⁺,and the decrease of the exchangeable Ca²⁺in soil near the source solution indicated that the formers were absorpted and the later was desorpted by the soil collision.

Abstract:The effect of a test reformed low beneficial protection forest established on the Huaying mo untain has been observed and appraised.The result shows that the soil conservation effect of the forest is obvious.Having been implemented reformatio n for five years,the mean value of soil erosion modulus by measuring fo ur runoff fields in test forest was merely 34.056t/km².The value was 1.39% of the mean soil erosion modulus in Hechuan city.With lush vegetation in test forest,the effect of rain intensity on soil erosion have retreated from the first place,it was merely 1/6 of that of precipitation.

Abstract:The types and characteristics of deformation and breaking of terrace bank slope in the western part of south Shannxi province are studied. Based on soil property trial,the authors point out the earth type and soil property which result in bank collapse is severe in constructing terrace.According to the soil characteristics,the authors also put forward some principles for terrace constructing,and measures for increasing terrace bank stability.

Abstract:Anti-erodibility is one important index to estimate soil anti-erosio n capacity which has relation and difference with anti-scouring ability.There are tho usands of hundreds hectare Hippophaer hamnoides forest in loess plateau region,and its anti-erosion capacity has been paid more and more attention.One scientific,effective and advantage evaluation system is essential to evaluate anti-erosion capacity of Hippophae rhamnoides forest.Using principal component analysis,different evaluation system—“Optimum 1 Index”,“Optimum 2 Indexes”,and“Optimum 3 Indexes”are chosen among many indexes.

Abstract:The measurement of trace elements in water samples is a fundamental laboratory work for element transport in both soil and runoff.It is usually done by using a flame atomic absor ption spectrophotometer.Howerer,an extraction procedure by adding methyl butyl ketone(MIBK, for short) is necessary when the element concentration in the samples is very low.An improvement on the method is made by using concentrated water sample in order to increase the concentration of trace elements in the samples.The interfering problem of silicone on the concentration is solved by adding calcium chloride.The results show that the improved method is simple,and both the recovery rate of the samples and the accuracy of the method are satisfactory.

Abstract:Based on soil and water conservation comprehensive control project of Lushan county (1992～1996),soil and water conservation engineering of slope and gully,forest and grass protective system constructing,soil and water resources utilizing,goods base constrcuting and benefits are studied.The authors point out that soil and water conservation is the base for the development and land management in mountainous area,it also has more significance for their economic sustainable developing.

Abstract:Based on shale properties analysing,the results obtained are that shale is easy to weather under the humid and hot climate condition,when vegetation is destoried,soil and water loss will be more serious.Shale erosive area has following characters:(1) low capacity to resist weathering;(2) sterile soil and wick ecological environment;(3) economic backwardness. According to those characters and control practice of Yichang county,Hubei province,many control measures are put forward:(1)constructing protective system of vegetation;(2)controlling gully slope combining with gully;(3)combining control with exploit;(4)combining use with energy saving and building comprehensive protective system.

Abstract:Based on the data of man made soil and water loss(1986～1992) in Guangdong province,the authors studied the main factors of man made soil and water loss,and its economic loss,increasing rate and harm,then put forward the countermeasures of the prevention and control.The sequence of sum total index in all items is:capital constructionmining reclaiming wasteland with steepslopebrickkilndestroying forest and vegetation.The economic loss is 31.36×10⁴yuan/km² (RMB),an average increase of 414.06 km² and 2 926×10⁴ m³.The authors put forward that man made soil and water loss result from the irrational human actions, as long as execution of the soil and water conservation,supervision and necessary measures of rehabilitation and prevention are enforced, much man made soil and water loss would be refrained, prevented and controlled.

Abstract:According to field positional experiment materials of natural and artificial rainfall and the water brushing,remote sensing of soil erosion types,and sediment of Wangdong gully small watershed,soil erosion laws and sediment reduction benefit,especially runoff and sediment yield on hard surface were studied.It has been proved that runoff brush from farmland and hard surface of village is a main reason for gully head rapid extending,the gully-slope road erosion is an important factor limiting sustainable development of farm economy.Gully-slope development engineerings which were built by the help of experimental station,made gully-slope eco-environment gradually turn into fine circle,the gully slope of bare mountain far from village had been replaced by new scene with road nets and full mountain fruits,and turned into economic gully slope

Abstract:Heihe reservoir is the important water resource project of Xi'an city.Protecting the ecological environment of the confluent region of the reservoir is the key to protect water quality.Based on the basic features of Heihe reservoir's confluent region,the main countermeasures to protect the ecological environment of the confluent region and realize the sustainable development are discussed

Abstract:There is serious soil and water loss in Wuhua county of Guangdong province,it prevents the production,living,and development of local industry and farming.After more than 10 years treatment,a great benefits of society,ecology,economy,sediment interception and runoff storage are attained,and a successful experience for soil and water conservation is found,it constructs a firm developing base for industry,agriculture and economy of Wuhua county.Soil and water conservation is a very great work,it must be carried o n perma nently.

Abstract:The middle and lower reaches of Jialingjiang river with a serious soil erosion,is a major region of soil and water conservation in the whole country.A conclusion is obtained by analyzing the documents of runoff and sediment in Lizixi basin, a typical basin of the reaches.Because of taking control and protect measurement into the ecological environment,soil erosion in the basin shows a tendency to decrease in a recent decade.Comparing with sediment discharge in years from 1965 to 1984,sediment discharge from 1985 to 1994 reduced 58.3%.Therefore, if the experience and measurement of controlling soil erasion of the basin are spread to other areas of the reaches,the condition of serious soil erosion in the middle and lower reaches of Jialingjiang river will be distinctively improved

Abstract:The Huaihai state operated farm of Jiangsu province transforms coastal saline alkaline soil by constructing low lying paddy fields surrounded with dykes to drain the waterlogging.The comprehensive productivity and economic benefit were increased obviously.By analyzing their successful experiences systematically,some reliable basis for the development,utilization and management of saline alkaline soil in coastal regions.are provided

Abstract:Based on the data of long term development in cereal production of national experimental demonstrative site in the loess plateau,the author suggests that cereal yield of 800 millions kilogram could be increased in Weibei area of Shaanxi province.The yield of unit area can reach 3750kg/hm² for wheat,6750kg/hm² for corn and 4050kg/hm² for cereal.And three approaches for increasing yield are suggested.The author points out clearly that barn target is not appropriate for Shaanbei area.The appropriate target should be eco-agriculture construction and more than selfsufficient for cereal production in this area based on the agricultural ecoenvironment condition.

Abstract:Annual variation characteristics of sediment yield on the loess plateau are analysed by using 16 feature indexes,and the annual variation characteristics of sediment yield in different regions and watersheds are obtained.The result showed that the annual average sediment yield(1955～1986) on the loess plateau was 15.2×10⁸t,the maximum sediment yield was 32.83×10⁸t(1958),the minimum was 4.96×10⁸t(1965),and the ratio between maximum and minimum was 6.62,between maximum and average was 2.16,the coefficient of variation was 0.56.On the loess plateau,there are 12 years in which sediment yield is more than average value,and 20 years in which sediment yield is less than average value,the proportion in the total years is 37% and 63% respectively;the sediment yield of more than average is 277.85t,the sediment yield of less than average is 208.52t,the percentage in the total sediment is 57% and 43% respectively.In the 32 years,the years in which sediment yield equals to less than 0.5 times,0.5～1.0 times,1.1～2.0 times and 2.1～3.0 times of the average sediment yield are 6,15,8 and 3 years;the propotion in the total years is 18.8%,46.8%,25.0%and 9.4% respectively.

Abstract:According to“Economic Evaluation Standard of Water Conservancy Construction(SD72-94)”,basing on mathematic model of economical analysis for net benefit,investment returning year, ratios of benefit and cost as well as internal returning rate,the computer program of economical analysis has set up by means of computer.The computer system has the characteristics of science,standard and rapidity,it should be popularized in a large area.

Abstract:Basing on lots of facts,using contrast analysis method,the natural conditions,population,cultivated land ,food,quality and quantity of cultivated land,the factors affecting economic development and social progress of Qinghai province are analysed.The results show that in order to obtain agricultural development,especially food production,increase self sufficient level,we must protect cultivated land depending on the law,exploit cultivated land resource and enlarge cultivated land,increase food productivity, promote investment;intensify base;carry out 《the Law of Birth Control》 and strictly control population increasing.