Abstract:Sediment yield and delivery in the middle reaches of the Yellow River basin, especially at the loess hill and gully areas, is a primary cause of rapid bed accretion at the lower reaches of the Yellow River. Water flow, wind and freeze and thaw weathering are the important external erosion forces contributing to sediment yield and delivery. Of these three factors, freeze and thaw weathering has not received adequate attention from researchers, given the magnitude of its contributing effects. The environmental background, action mechanisms and representative modes of freeze and thaw weathering occurring in the loess hill and gully areas of the middle Yellow River basin are described and discussed. The sediment yield generated by freeze and thaw weathering in the sandstone area is about 1/2 the sediment yield generated by gully erosion in the area and 1/3 of the total sediment yield of stream catchments, with variations depending on gully lithology, gully sediment yield and other measured data.

Abstract:Setting three-dimensional drainage system which is composed drainage culvert and horizontal, vertical and acclivitous drainage bore in loess landsliding body, is an effectual method for dropping the underground water level and improving the stability of slope, but its effection estimation is a problem. The 3D seepage numerical analyze is an effectual method to solve the difficulty. The three-dimensional drainage system in a typical loess landsliding body at Guanzhong section of Weihe River is simulated with 3D seepage numerical analyze method. The results show that because of complexity of stratum in landsliding body, the infiltrative coefficients obtained with indoor testing do not accord with naturalness, the anti-analyze is needed according to the determined underground water level on the spot; the space and position between drainage bore hugely influence the effect of dropping the underground water level.

Abstract:Water movement in the form of preferential flow does not follow Darcy's Law. Pipe flow is one kind of preferential flow. To study the effect of pipe flow on soil water movement, a natural, secondary, largely undisturbed Pinus massoniana woodland in the granite region of the Three Gorges of the Yangtze River was selected as an experimental plot. Properties of seven soil layers were measured using a double cycle infiltrator. Pipe flow and infiltration was recorded using automatic flowmeters. Rainfall also was observed over the same period. The results show that the infiltration capacity of the soil is related to the higher proportion of weathered granite in this region relative to other areas. Of the seven soil layers measured, the surface layer (0—10cm), has the lowest infiltration capacity. It is probably due to a higher clay content in the surface layer relative to other layers and a fine texture characteristic. An impervious layer occurs 150—200cm below the soil surface. Pipe flow mainly is generated over this layer. At the initial stage of rainfall, the soil water moves as unsaturated flow. First, continuous flow does not be occur and pipe flow is not generated during this stage. With continued rainfall, the soil becomes saturated and pipe flow begins. The production of pipe flow demands higher soil water content than that resulting from average infiltration in the soil profile.

Abstract:The activities of soil urease, sucrase, neutral phosphatase and catalase in different soil layers, vegetation community and land use in the Yunwu Mountain area are studied. The result shows that: the activities of soil sucrase, urease, neutral phosphatase and catalase are all higher in the upper layer of the profile and decrease with the depth. Under the enclosed condition, four different enzymatic activities in surface layer soil(0—20cm) is greater than sub-layer(20—40cm). The activities of soil urease, sucrase, neutral phosphatase are Stipa gradiss.+Stipa bungana Community Artemisia sacrorum community Stipa bungana community Thymus mongolicus community in the surface layer(0-20cm). The activity of soil catalase is Artemisia sacrorum community Stipa gradiss. + Stipa bungana Community Stipa bungana community Thymus mongolicus community. Under the two different land use of Stipa bungana community, the activity of soil urease shows that the farmland is greater than enclosed land, but the activity of soil sucrase is enclosed land greater than farmland. There is no obviously soil erosion and no the enzymatic activity difference between the farmland and the enclosed land in the study area. So it also shows the correct land use can prohibit the soil degradation.

Abstract:The middle and lower reaches of the Liaohe River are located in the old industrial region of northeastern China and are important for food production and stockbreeding. Based on multi-temporal remotely sensed data from Thematic Mapper, this research attempted to reveal the spatial-temporal trends in land use and its impact on the eco-environment in middle and lower reaches of the Liaohe River. The results suggest that, in the last 15 years, the area of cultivated land increased and aggregated rapidly, while the area of woodland, grassland and water decreased considerably. The dominant land use change types were the conversion of woodland, grassland and wetland into cultivated land. The dynamic change of land use has had many effects on the local environment, including intensive soil erosion, increasing nitrogen content in the river and biodiversity loss in the region.

Abstract:Central Guizhou Province, where the economic development is being promoted, is receiving an influx of rural labor workers. The dependence of the rural population on land is declining. Consequently, some areas that had become rocky and desertified are in a process of recovery. With this background, the author gathered soil samples of surface layers and carried out chemical analyses. The results show: the accumulated quantity of soil organic matter and N is higher, and it is highest in areas without obvious rocky desertification and lowest in areas with moderate desertification evident. Bedrock material slightly influences the variation in total P and K. The amount of rapidly available N and K is high, while the amount of rapidly available P is very low.

Abstract:Seting Yanan City as an example, the soil and water loss during the urbanization in the Loess Plateau area and its negative impact on the urban eco-environment are analyzed. The human activities of urbanization will speed up the soil and water loss leading to endangerments, specially such as the increase of the silts in rives, the lift of the riverbed as sedimentary deposits, the pollution of water, soils and air, and resulted in flood and geology calamities. The aim of the article is to lead us paying more attention, to explore the protective and controlling ways and means of solving the questions, to minimize the soil and water loss due to human activities in urbanization, specially in the Loess Plateau area of dense hills and gullies resulted in serious soil and water loss, in order to provide safeguard and service to the construction of better cities'eco-environment.

Abstract:By means of field investigation and research in combination with spot reconnaissance, according to the plan of soil and water conservation of the West Gas Supplying to East Project, the paper has comprehensively evaluated the soil and water conservation precaution and protection, the engineering and vegetative control measures, the land reclamation measures, the implementation of soil and water conservation investment funds, and the supervising and monitoring of soil and water loss. Some proposals concerning problems of soil and water conservation measures lower quality and lagging behind the principal part of project are put forword. It is very important to enhance environment protection and carry out the soil and water conservation system of simultaneously designing and constructing and put it into operation.

Abstract:In the 1980s, the intensive and irrational use and development of natural resources in the mountain areas in south Jiangxi Province caused serious water loss and soil erosion. Some farming lands were desertified. The erosion resulted in ecological deterioration, which led to increased poverty in rural areas. The increased poverty, in turn, exacerbated ecological deterioration. The MRL Project was implemented in Jiangxi Province in the 1980s. The project involved selection of a typical watershed in the mountain region as an experimentation and demonstration area in which to carry out ecological agricultural modelling. The principle "harnessing the mountain should harness the poverty" was proposed. The "plant trees up the hills, plant fruit in the middle of hills, stockbreed down the hills and integrate planting and stockbreeding" model, the "pig-biogas-fruit" eco-agriculture model, the "courtyard economy" model and the "feudal economy" model were popularized and vigorously developed throughout the basin. This integrated watershed development model for mountain areas appears to be the most effective way to develop the economy in southern Jiangxi Province. The project also presents a good example for the sustainable development of natural resources and ecological protection in mountain areas in the south of China.

Abstract:Seeds of the Caragana intermedia and Artemisia schrenk songarica in Maowusu sandland were treated with different strongths of electric current. Under controlled conditions the effects of the exposure to electric fields on the drought resistance of the seeds in the germinating stage were tested. The results show that electric field treatment can reduce the negative impacts of drought. The different electric field strengths have different effects on the drought stress adaptability of the seeds in the germinating stage and on plant biomass. It is concluded that electric field treatment can increase seed germinating potential, germination rate, plant biomass and both wet and dry weights. All these changes are favorable for reducing drought damage and improving plant adaptation.

Abstract:The influence of land use/land cover change on ecosystems is one of the most active frontiers of land science research in the world. This paper examines the influence of land use and land cover change on a regional ecosystem, with a focus on aspects including biodiversity, climate and land degradation. The results indicate that land use affects biodiversity in Fujian Province both positively and negatively due to different types of change in land coverage. Land use affects the climate, mainly by changing the land surface albedo and atmospheric composition. Different types of land use lead to different degrees of soil erosion and soil nutrient loss. The paper also considers the effects of land use on wetlands.

Abstract:Spatial variability of some soil properties at a 20 m long hillslope on the Loess Plateau was studied with the classical statistical analysis. The results show that in the same soil profile, sand, silt and clay contents have small variability, and organic matter content decreases from upper layer to lower layer with moderate variability. Soil dry bulk density has small variability, but saturated hydraulic conductivity has moderate one. Soil water characteristic curve has some spatial variability and specific water capacity has moderate one. The isograms of soil saturated hydraulic conductivity and dry bulk density indicate that the change of soil saturated hydraulic conductivity does not only depend on soil dry bulk density, and has some relations with organic matter content, clay content and root distribution.

Abstract:Based on the arid, barren, precipitous ecological environmental conditions of expressway high and steep slope soil in the loess plateau of Shaanxi Province, the paper proposes some measures as follows: (1) to adopt the rainwater to superpose utilization and transposition locality utilization to raise the content of soil moisture of the terrace soil; (2) to lay the two-dimensional network cushion and geotechnological dose of rooms; (3) to reconstruct the organic fertilizer, and to raise the soil fertility; (4) to choose the suitable tree or grass species to native soil, and apply some technological measures in order to improve the afforest survival and preservable rate on high and steep slopes of the highways.

Abstract:Geostatistics combined with geographical information system(GIS) techniques were applied to a treatment and analysis of the spatial heterogeneity of soil nutrients in topsoil(0—20cm) at Hailun County of Heilongjiang Province. Sixty-five soil samples were collected from the central farmland of Hailun County. The results indicate that the semivariogram of total C and total P are best described by the Gaussian model; total N and total K are best described by the exponential model. Analysis shows that the spatial correlation of total C and total N at this large scale is moderately dependent, with Nugget/Sill were between 25%～75%; therefore changes in total C and total N are affected by both structural and random factors. The spatial correlation of total K and total P is highly dependent, with Nugget/Sill were less than 25%; therefore, changes in total K and total P are mainly affected by structural factors. There is high spatial correlation between total C and P. Spatial variability results from the geostatistics method were compared to soil fertility survey in 1978 results from Hailun farmland. The analysis is useful to inform strategic planning of farm production, to guide fertilizer application and to control soil erosion and degradation of Blacksoil, in northeastern China.

Abstract:The database of land use can provided more accurate and more scientific decisive information for the optimal management model of land resource if only spatial data origins are renovated periodically. In the process of constructing land use database in Jingbian County, the data collection, the decision on spatial data origins, the data handling to the construction of land use database are planned and evaluated based on GIS at county level. The flow diagram and the techniques of the work to minimize the information loss in transforming from the investigation result at present land use to the land use database are studied with the help of GIS.

Abstract:There are a lot of vast and narrow plain in the Qin-Ba mountain area of South Shaanxi Province, which is regarded as the essential things. For a long time, local people have worked hard to build their farm land by reconstructing the bank and have acquired great achievements. However much plain can not still get rid of flood rushing calamity, and some have been rushed and repaired once and again; others have been submerged under the mud and sand. Slope and steep land of the mountains is increasing decreased and the soil fertility drops year by year, during tens of years, the average farmland per people of South Shaanxi Province has dropped from more than 0.2 hm² to 0.067 hm², what is more, it has dropped to little than 670 m² in some counties. To protect the basic agriculture land, prolong the usable life of plains in the river, and keep a sustained development, based on a great number of investigation, this article investigated and analyzed the reason of the producing calamity, and then put forward a very good suggestion about repair plains in the river.

Abstract:Tengchong County of Yunnan Province is located in the southern region of Hengduan Mountain. From July 17 to 19, 2004, an extraordinary rainstorm struck suddenly over Houqiao, Mingguang, Diantan, Gudong, Jietou, Qushi and Zhonghe villages and towns in the central and northern part of Tengchong County. This event triggered landslide and debris flow disasters over a large area. During the catastrophe, nine local residents were killed or disappeared and nearly 136 million RMB of properties damage occurred. This study shows that the rainstorm, with rainfall of 159.6 mm within 24 hours and reoccurring frequency of 60 years, was the main cause of the disaster. Based on the characteristics of the area, the current situation and the tendency for geological hazards to develop, eleven mitigation measures currently in place or possible in the future are put forward.

Abstract:Since the downstream flood disaster on the Weihe River, water logging in the northern areas of the Weihe River has aroused the attention of the masses and leaders in different levels of the government. This article discusses how to efficiently limit water logging and rebuild after extreme events on the basis of the current status of the problem and rebuilding experience. Causes and specific management measures are also put forward.

Abstract:The headstream basin of the Yellow River is ecologically important to China, but it has become threatened by soil erosion in recent years. This paper examines the general situation of soil erosion on the basis of a 2002 survey by remote sensing. Analysis indicates that frost-thaw erosion is the major erosion type in the region. Water erosion occurs in the eastern mountainous areas at a generally light intensity, while wind erosion is concentrated in several areas at a high intensity. The northwest erosional area experiencing water-wind erosion is the portion of the region experiencing the most serious soil erosion of the four areas of erosion in the region. The area of soil erosion in western part of the headstream basin is relatively small, but it still poses a serious threat to the ecological stability of the basin, which is a fragile area and in which rehabilitation after major erosion is very difficult. Land use/cover change(LUCC) is discussed, with particular reference to the establishment of grasslands and wetlands as means of erosion prevention and ecological rehabilitation.

Abstract:Based on the status of soil and water loss in Red-soil hilly area of South China, soil and water conservation effects of terrace on soil and water conservation are analyzed. The results show that terrace has obvious soil and water conservation effects, and its soil conservation benefit is better than its water conservation benefit. Under the same condition of terrace, biology measure integrating engineering measure can greatly increase soil and water conservation effects.

Abstract:Based on study of the spatial-temporal characteristics of polder numbers and arable land resources in Dongting Lake area, this paper provides an analysis of the formation, changing trend and current utilization of polder land. The paper also highlights the process of ecological restoration and economic development under the instruction of"destroying dykes and changing reclaimed paddies into lake areas". A number of problems are discussed, including the contradiction between population growth and arable land decline, and land pollution and land degradation. Six management measures for the sustainable utilization of polder land in the region are put forward. Those are (1)to adjust agricultural distribution and planting regimes to ensure optimal land utilization system under changing land resource characteristics and maintained sustainability; (2) to adopt disaster-mitigating agriculture aligned with the ecological environmental conditions of polders; (3) to construct water facilities in line with national projects for agricultural environment protection; (4) to strengthen the overall planning and management of agricultural land utilization; (5) to strengthen the awareness of environmental protection and arable land resources quality enhancement; (6) to actively popularize the water-conservation irrigation techniques.

Abstract:Ecosystem in most regions of China has characteristics that create potential for natural rehabilitation. The potential for natural rehabilitation has been demonstrated in theory and by experience. The guiding ideology of soil and water conservation should change from engineering intervention to dependence on ecosystem self-rehabilitation. There must be a positive change in thinking away from controlling valleys. The distribution and measure of efforts should agree more with natural ecosystem processes and serve to reduce negative disturbance of natural processes. Action should be taken with the intent to harmonize human activity with nature. To support these actions, many aspects of soil and water conservation require strengthening, such as prevention criteria, assessment index system and regionally specific key management techniques and measures.

Abstract:The north slope of Dabie Mountain is located in a climatic transitional zone, at which semi-tropical conditions give way to temperate conditions. The area is a fragile and sensitive ecotone, which is characterized by weak feedback relationships that tend toward instability. There is considerable soil and water loss in the area. Soil and water conservation and ecological restoration may contribute to the functioning of irrigation works at Pi-Shi-Hang, prevent flooding of the Huai River and reduce the pollution of Chao Lake. Implementing ecological restoration is an optimal approach to restore water and soil quality in degraded areas. It is proposed that the program of ecological restoration of the north slope of Dabie Mountain include: ecological reconstruction involving land use change from tillage to woodland; integrated land and water use across the small watershed; efforts to encourage collective attention and action; construction of a small power station; and an aim to make conservation facilitate development and vice versa, so that the nature, the economy and society are managed harmoniously.

Abstract:After estimating the potential resource of rainwater in Wangwa watershed in Pengyang County, the relationship between its potential and supply was appraised based on the development programmer of water saving agriculture and actuality of land use and rainwater data in the watershed. The results showed that: (1) the potential of theoretical resources of rainwater was 7682598 m³, the ratio of using in the same spot , different spot and rainwater collection reiterative utilization is 50.96%, 7.16% and 41.88% respectively. (2) Potential of realistic rainwater was 7164885 m³, which was 93.26% of the potential of theoretical resources. (3) the demand of water in demonstration area was 3 739 352m³, just was 52.19% of the potential of theoretical resources, the remain of Potential of realistic rainwater could be used. (4) the result on assessment of rainwater using in the watershed suggested that the scales of rainwater using was insufficient, so it should be a efficient approach of rainwater resources to enlarge the scales of rainwater using in the same spot.

Abstract:By reviewing the development history of warp land dams construction in soil and water conservation， this article expounds the important significance in doing well in warp land dam construction demonstration and shows the driving roles of the demonstration plays in the dam construction. Focusing on the four phase of feasibility study，design construction management，operation and maintenance in warp land dam construction，some ques?tions related to warp land dam construction for demonstration，attention for which should be attached are analyzed. Also the advantages of conducting warp land dam system construction with individual tributary as one unit are i?dentified in terms of soil and water conservation in the Yellow River basin and warp land dam development for a long run and some crucial circles in implementing warp land dam warp land dam system construction in tributary dam system are listed，aiming at providing reference for counterparts eng aging in warp land dam construction.