Abstract:By using meteorological data in the area of the first meander of the Yellow River and data of both annual runoff in the upper reaches and the cutoff in the lower reaches,climate changes in the meander area and their effects on annual runoff in the upper reaches and the cutoff in the lower reaches were analyzed.Results showed that in the meander area, annual precipitation tended to decrease and fluctuated in three periods of 2-4,6-7 and 10-11 years.The mean annual temperature was remarkably greater than that of other areas in China.The departure of annual temperature was low before 1983,and high after 1984.Annual runoff of the Tangnaihai fluctuated in two periods of 4-5 and 14-16 years.The waves for annual precipitation in the meander area and annual runoff of the Tangnaihai were basically agreed.The mean annual temperature was high,sometimes,whereas annual precipitation and annual runoff were low in 1990s.The fluctuated trends of annual precipitation in the meander area and the cutoff in the lower reaches were on the contrary.The climate changes in the key and sensitive area of the upper reaches of the Yellow River greatly affect the water resources of the region.

Abstract:The experiment was conducted with standard runoff treatments.Quantitative analyses of the runoff coefficient and the amount of soil erosion under different soil and water measures were made by means of statistical methods.Results showed that it was an effective approach to raise the level of vegetation coverage with necessary engineering measures supplemented for soil and water conservation in sloping land of red soil.Especially after planting grass on level bench terrace wall,the capability for decreasing runoff and the capability for controlling the amount of soil erosion increased 22.5 and 30.62 times,respectively.

Abstract:The ¹³⁷Cs tracing method is extensively used in the research fields of soil erosion and sediment transportation.For using the method,it is very important to determine the relationship between ¹³⁷Cs and the composition of soil particles.However,at present,research on this aspect is not well conducted.So,based on the data of 39 soil profiles in different areas of red soil,this paper analyzed the relationship between ¹³⁷Cs content and the composition of soil particles using statistical methods.The result showed that ¹³⁷Cs had a positive correlation with sand and silt contents,and had a negative correlation with gravel and clay contents within 20 cm of the soil surface.Then through correlation analysis and stepwise regression analysis,it was found that in different layers,sand content was the main factor contributing to ¹³⁷Cs.The quantitative model for the relationship between ¹³⁷Cs and the composition of soil particles was constructed.The model showed that ¹³⁷Cs increased with the increasing of sand content.

Abstract:The characteristics of arable-land resources and utilization,the basic processes and regional differences of changes in arable-land areas were revealed according to the statistics data of arable-land areas from 1986 to 2002 and the detailed investigation of land use in the recent 5 years.Also,the driving mechanism for the changes in the cultivated land areas was discussed.The main conclusions were as follows.(1) There was a trend of obvious fluctuant decrease in arable-land areas in the past 20 odd years.The changes of arable-lands underwent the process from a gentle decrease to a sharp decrease,then to a slow decrease.(2) The decreased arable-lands were mainly inverted to project and mine lands,residential areas,various traffic lands and orchards.The increased arable-lands mainly came from the exploitation and reclamation of non-utilized lands and the arrangement and resumption of project and mine lands.(3) The economic development,population growth and policies were the dominant macro-driving factors for the decrease in cultivated land areas.The obvious break in the change process of arable-lands was related to the national macro-policies.The rapid decrease of cultivated land areas coincided in time with the overheated economic growth resulting from the direct investment in fixed assets.Spatial distribution of the decrease in arable-lands matched the differences in speed and scale of economic growth in different regions of the Longdong Loess Pleteau.

Abstract:"The One-Millionth Weihe River Map" compiled in 2005 reveals that the areas around bridges are the typical nodal points on the Weihe River.Using the measured data along with the map and other relevant information,this paper concludes that the main river channel becomes narrow as side shoals build up around the bridges.The main river channel leans toward one side of the bank,and curved waterway develops up and down the bridges,which imposes great eroding force to the bank.The maximum discharge by the bridges neither bears the flood with return period of 100 years or over if the roughness coefficient n=0.025 nor bears the flood with return period of 30 years if n=0.035.The gradient around the bridges becomes smaller than that of others on the river,generally leading to the turning of the river bed and the piling-up of sands,hence smaller gradient and lower water flow speed.The bridge areas in the urban quarter of Baoji City,especially the area around the Wolongsi bridge,become the greatest threat to the city when flood occurs.

Abstract:Based on the applications of GIS and RS and the indices such as diversity, dominance, evenness, frag-mentation, isolation, etc. , the landscape mosaic structure of Wufendigou experimental area in Huangfuchuan basin was studied. In terms of fractal dimension, the complexity of all landscape types was analyzed by constructing the fractal structure model of all landscape types and through using fractal theory and concerned quantitative methods.T he steppe landscape is dominant but not apparent in its patch and area, and the percentage of the original vegetation of Stipa bungeana steppe is very low in the study area, which is apparently characterized by human disturbance. The diversity and evenness of patches in the study area are higher than those of the steppe landscape area,and the fragmentation and the isolation of the steppe are the highest. The landscape shapes of artificial arbor woods and cultivated lands are the simplest, and the landscape shapes of classical steppe and artificial shrub are in an instable stage. From above results, we can conclude that it will spend a long time to restore original vegetation in the study area because of the strong disturbance and the unreasonable landscape structure.

Abstract:The properties of biological soil crusts and their effects on soil water,organic matter and soil erosion on the lands abandoned during vegetation restoration in Duntan Hills,Ansai County,Shaanxi Province,which is located in the hill and gully region of the Loess Plateau,were analyzed.Results showed that:(1) after the abandonment,the coverage and thickness of biological soil crusts increased gradually with the increase of time,and the thickness varied from 0.1 to 0.3 cm;(2) the soil water content in the sample plots without biological soil crusts was higher than that in the sample plots with biological soil crusts,and the soil water content increased with the increase in soil depth within 0-40 cm of the soil surface;(3) the organic matter content within 0-10 cm of the soil surfaces in the sample plots with biological soil crusts was higher than that of the sample plots without biological soil crusts,and the relation was the same in the soil layers of 10-20 cm,but the variation was not distinct as within 0-10 cm of the soil surface;(4) after the abandonment,the amount of soil erosion decreased gradually with the increase of time,and compared with the early abandoned plots,the amount of soil erosion in the sample plots in more than 10 years decreased by 30%-80%.The results illuminate that biological soil crusts could improve the characteristics of soil surface layers on the abandoned lands during vegetation restoration,and enhance the soil ability to resist erosion.

Abstract:Soil water availability and water storage were comparatively studied for the arbor(including Prunus sibirica and Robinia pseudoacacia),shrub and farmlands.It was followed that soil water availability of different vegetation types ranged from 1.92% to 15.73%.In comparison with farmlands,soil water availability on woodlands increased by 75.31%.Total soil water storage within 40cm of the soil surface ranged from 228.30 to 251.07 t/hm².In comparison with farmlands,total soil water storage capacity on woodlands increased by about 8%.Total water storage capacity of Robinia pseudoacacia was greater than that of Prunus sibirica.This study was of significance to assess the benefits of soil improvement in the regions of converting farmlands to forest or grass lands.

Abstract:The authors defined an index of soil erosion severity,calculated its value for each county,and analyzed index classification.Based on these works,745 counties with sever soil erosion in China were presented.The area and distribution of soil erosion for the counties prove the index of soil erosion severity.The index is the weighted mean of erosion degree and area,which not only reflects erosion area in the round,but also discriminates each grade of soil erosion severity.

Abstract:Salix viminalis was the strongest among all strains of the S.Jiangsuensis planted in the plot A and B in the fluctuation zone of the Liujiaxia Reservoir.In plot A,survival rate and preservation rate were 97.30% and 96.20%,respectively.Compared to the S.Jiangsuensis '172',tree height,breast diameter and the new branch and tree top increased on average by 12.98%,12.50% and 10.28%,respectively.The underground root systems and the plenty of adventive roots growing on basis trucks can greatly reduce soil erosion by reservoir water.The 1 m×1.5 m allocation density of the Salix viminalis showed the best protection,and sediment yield was 8.64 kg/m²,which decreased 74.38% compared to CK.The fluctuation land with a small slope is suitable for survival and growth of willow.

Abstract:The Weihe River is the greatest river in Shaanxi Province.Its water pollution becomes very serious in recent years and has restricted the development of local economy.The temporal and spatial characteristics of variation in the pollution indexes of COD_(Mn) and NH_3-N,and the reasons for the variation were analyzed based on the data of water quality observed from 1991 to 2002.Results show that the Weihe River has been polluted seriously,in which the most serious COD_(Mn) pollution was observed at the Xianyang Railway Bridge,and the serious NH_3-N pollution was also observed at the Wolongsi Bridge,the Guozhen Bridge and Xingping City.Pollution of the river has become more and more serious since 1990's,with the highest value of NH_3-N observed in 1996 and the highest value of COD_(Mn),in 1995.The polluted water from paper mills is the main source of COD_(Mn) pollution,and chemicals applied on farmland and the discharge of waste water by fertilizer industries is the main reason for NH_3-N pollution.

Abstract:The West-to-East Gas Pipeline Project goes across the middle of China and suffers various complex landforms along the pipeline.The project construction has caused plant deterioration,soil erosion and desertification.Therefore,it is necessary to take vegetation recovery measures to prevent and control soil erosion as well as environment deterioration.In this study,we divide the construction area into two land types and six site types on the basis of synthetic analyses of the factors such as climates,topographic forms and soil conditions.To solve the soil erosion and environment problems in the Ningxia region raised by the West-to-East Gas Pipeline Project construction,we present soil and water conservation and vegetation recovery measures to resume and rebuild the ecosystem,which has a great significance not only to build the west-to-east green corridor and ecology belt,but also to ensure security of pipe and ecosystem.

Abstract:The establishment of a new course framework is the kernel of the teaching reform for the major of Soil and Water Conservation and Desertification Control.In this paper, a history of the teaching reform and characteristics of the major was reviewed.A framework of the course system was presented according to the relationships between the courses and the needs of society.It is recommended that the course framework should include 16 basic courses,5 lower and 2 upper level major courses,and 12 optional courses.

Abstract:Soils of the 5 year sea-buckthorn and mountain peach mixed forest and the mountain peach pure forest in the semiarid degenerated mountain area were analyzed.Soil organic matter and nitrogen of the mountain peach and sea-buckthorn mixed forest were distinctly increased. In the 40-60 cm active layer of the forest root system,soil organic matter and nitrogen were higher than those of the mountain peach pure forest,and the increase in available phosphorus was less,and available potassium increased a little.

Abstract:This paper was intended to solve the main eco-environmental problems of the alpine meadow in the upstream area of the Xiliao River.Based on natural and economic conditions of the area,the distribution and construction techniques of an integrated protection forest system were studied systematically,and its protection effects were investigated preliminarily.The integrated protection forest system covers 46 800 hm².The main part of the system is the shelter forest for farmlands,which is combined with trees,shrubs and herbs,as well as forest belts,forest nets and forest patches.Water resources conservation forest,soil and water conservation(forest and eco-economic) channels are the important compensations.The percentage of forest coverage increases from 11.8% to 23.3%.At present,effects of the shelter forest for farmlands are not so significant,but grass yield,grass species composition,physical property and nutrient status change greatly in the deteriorated grasslands.The integrated protection forest system may greatly accelerate sustainable development of the regional environment,economy and society,and maintain ecological security of the midstream and downstream areas of the Xiliao River and the capital of China.

Abstract:The method of planting grassland with strip trenches and grass blocks was studied in eroded hillside fields.After planting grassland with strip trenches and grass blocks,the amount of soil and water loss in the runoff plot within 3 months was only 140 kg.It decreased 823,249 and 670 kg,respectively,in comparison with the plots of no-planting with soil surface prepared,original slope surface and contour planting with full reclamation.Soil and water loss rate in the runoff plot with strip trenches and grass blocks was 1 500 t/km² in the first year.It reduced 10 591,3 514,and 7 760 t/km²,respectively,in comparison with the plots of the no-planting with soil surface prepared,the original slope surface and the contour planting with full reclamation.Soil and water loss rate in the runoff plot with strip trenches and grass blocks was less than 700 t/km² in the next year.The types of grass vegetation increased from 6 to 16 after three year construction.Coverage rate increased by 85% in the first year of controlling eroded hillside fields.These show that soil and water loss can be controlled in a short time.

Abstract:According to the independence and non-compatibility of indexes in the decision-making of water-saving irrigation and the fuzziness in the choice of indexes and criterion,a new method based on the fuzzy matter-element is proposed for the project decision.The model begins with building the matter-element of optimal subordinate degree and relational grade and calculating the coefficient of weight by standard deviation.At last,the optimal scheme is selected by the relational grade.The outcome of the application to the water-saving irrigation decision in the watersheds of the Yellow River shows that the model is feasible and reasonable.

Abstract:Based on a simple discussion about the necessity of the road landscape design,the principles and requirements of the landscape design for ecological environmental construction are proposed.By taking the Yuxi to Yuanjiang Expressway as an example,the landscape design and the hopes to promote the development of road landscape and ecological environmental construction are demonstrated.

Abstract:It is difficult to find a reinforced measure for swelling rock slope due to its complex.In the study,Finite Element Method(FEM) was applied to analyze the law of displacement at the top of swelling slope with different joint spaces,bolt spaces and loads.The reinforced measure of swelling rock slope was simulated by FEM.The result can be devoted to find a reinforced measure for swelling rock slope.

Abstract:This article was intended to regulate the construction of a provincial forestry science and technology demonstration area,and enhance the quality and benefits of forestry construction.The guiding ideology,principles,goals,requests,procedures and the examination and certification for the construction of the demonstration area were formulated by the investigation of existing forestry science and technology demonstration areas.The article can be an instruction in the construction of the demonstration area.

Abstract:Rocky desertification in the karst area is a land degradation process in nature where the rate of soil for 2mation is lower than that of soil erosion. Slope degree affects the extent of soil erosion. The greater slope degree is ,the more instable surface material is. The two maps of slope gradient and desertification distribution on a scale of 1 ∶ 500 000 in Guizhou Province were overlapped and analyzed in order to discuss the correlation between slope degree and rocky desertification. It was found that slop degrees ranged mainly from 10 ° to 25 ° . Where slope degree was greater than 25 ° , the possibilitiesof the desertification occurrence at low , moderate or strong rate were all very high. In addition , the occurrence of rocky desertification increased as slope increased , especially where slope degree was greater than 18 ° , the trend toward strong rocky desertification was apparent. The desertification was mainly at low or moderate extent where slope degree was less than 18 ° . The reasons for the correlation between desertification and slope degree in this region were discussed preliminarily.

Abstract:Conditions of precipitation surface and underground water resources in the Guanzhong area were analyzed.Problems of water resource use such as the low efficiency of traditional irrigation were discussed.A proposition and the measures for construction of a water-saving irrigation zone in the area were presented.It is suggested that construction standards of the water-saving irrigation area must be formulated as soon as possible.A great attention must be paid to saving water in its delivery and improving the ways of irrigation.Also,attentions shouldbe paid to practicing biological saving water,extending the limited irrigation for a sufficient use of water resources,enhancing agronomic measures to save water,extending the soil surface measure to prevent soil water from evaporating,using new water resources and reducing expenses,and expanding the uses of non-convention water resources.These measures are the key to construction of the water-saving irrigation zone,and are the basic measures for sustainable use of water resources in the area.

Abstract:Based on resource survey,sample collection and document searches,wild ornamental plant resources on the Maowusu sandy land were investigated.It was found that there were 499 species of wild ornamental plants belonging to 172 genera of 83 families in the region.The current situation,ornamental characteristics and landscape engineering utilization of the resources were indicated.Advices on 3 stages of resources survey,species domestication and product development were presented.

Abstract:On the basis of field fixed-spot survey and investigation,soil erosion by water in rural settlements,soil erosion by earth discarding during new cave(or house) construction and soil erosion caused by cave collapse were studied in the loess hill area of North Shaanxi Province.From June of 2004 to October of 2004,the annual average soil erosion by water in rural settlements was 5 434.3 t/km².The annual average soil erosion by water on roads(between houses),open spaces(between houses) and yards was 7 348.0,6 873.2 and 2 081.7 t/km²,respectively.The average amount of discarded earth for a new-built cave or house was 34.9 m³,being 23.6% of the dug earth.The annual amount of discarded earth for all new caves(or houses) averaged over recent 20 years in the abundant and coarse sediment area of Yulin and Yan'an was as much as 7.96×10-7 m³,with annual soil loss by earth discarding up to 5.17×10⁶ m³(7.76×10⁶ t).According to the accumulated volume formed by 102 caves(houses) investigated,the annual earth loss per cave(or house) collapse was 46.3 m³.The annual amount of earth loss caused by cave collapse in Yulin was as much as 1.25×10-7 m³ (1.87×10-7 t).The above data show that the development of rural settlements brings out the more serious soil erosion.More attentions must be paid to the study,prevention and control of soil erosion in the region.

Abstract:In terms of the policy and system,this paper analyses the causes of environmental problems,and reviews the constraints of policy and system to the sustainable utilization of eco-environment and resources in the Northwest China.The paper also proposes the countermeasures for sustainable utilization of eco-environment and resources in the Northwest China.The countermeasures include eight aspects of organic agriculture,circular economy,overall development,energy exploitation,water resource use,urban poverty alleviation,and the prevention and cure of coal spontaneous combustion

Abstract:The paper first explicate the development mechanisms of Boyang Lake's water resource exploitation and protection in their three stages,i.e.the planning mechanism,the free allocation mechanism and the regulation mechanism by government interferences.It further points out that the failure of the planning mechanism is because people look down on science,the failure of the free allocation mechanism is due to "the tragedy of public land",and the active government interferences have positive effects.Then,the paper conducts an investigation and makes a positive analysis on effects of the three mechanisms;explains that the motive force of the change from the first stage to the second stage is different from that from the second stage to the third stage,for the motive force of the former is from the power of institution reformation,whereas the motive force of the later is the result of the punishment from the nature;discovers that effects of the mechanism change from the first stage to the second stage are not good,or become even more worse because "the tragedy of public land" happens widely,and effects of the mechanism change form the second stage to the third stage are becoming better because the government has enhanced the administration and protection for water resources of the Boyang Lake.Finally,the paper makes a conclusion that mixed market mechanism that the government regulation combines with the market mechanism is the best mechanism for the Boyang Lake's water resources to be used and protected.