GIS在土壤侵蚀分析中的应用研究进展

土壤侵蚀模型是水土保持规划中的重要方法,目前常用土壤侵蚀模型缺乏对空间数据的有效管理,因此使得它们在实际应用中存在因子获取和结果分析不便的缺陷。GIS对空间数据管理分析独有的优势使得GIS在土壤侵蚀中已经得到了广泛的应用,目前主要集中在土壤侵蚀模型因子获取、模型运算和结果可视化分析3个方面。土壤侵蚀评价信息系统就是三者应用的综合体现。

Ration Spatial Characteristics Analysis of Soil Loss Based on GIS and RUSLE in Jinzhou City

Supported by RS technology and GIS technology, the amount of soil loss and soil erosion intensity in Jinzhou City in 2010 were quantitatively evaluated by the modified RUSLE model. The characteristics of the spatial distribution of soil loss in Jinzhou City were analyzed. The results showed that the soil erosion area of Jinzhou City in 2010 was 7 284.87 km2, accounting for 70.72% of the total area of Jinzhou City. The average soil erosion modulus was 18.27 t/（hm2＆#183;a）, belonging to mild erosion. Two slope belts of 15＆#176;-25＆#176; and 6＆#176;-15＆#176; were the main soil erosion re-gions in Jinzhou City. Soil erosion in Jinzhou City was mainly concentrated in the rural residential land and the dry land, and the soil erosion amount of these two land types accounted for 60.97%of the total soil erosion amount in Jinzhou City in 2010. It was suggested that the treatment of these two land types should be strengthened and be main treatment object for soil and water conservation in future. The research could provide scientific basis for the governments to make policies about soil loss.

Synthesis Analysis of Soil Erosion for Three-River Headwater Region Based on GIS

In this paper,based on the common soil erosion model,the Three-River Headwaters region was select for study object. GIS methods are applied to conduct Semi-quantitative assessment for different types of soil erosion,and some results are concluded. The water erosion occurs in High Mountain and extra-high mountain of Yushu,Nangqian,Banma and Jiuzhi County in the southeast and south of the Three-River Headwaters region. The degree of erosion is prone to topography,precipitation,river and human activity. The freeze-thaw erosion mainly distributes in the northwest of the Three-River Headwaters region. The area of middle and above middle erosion degree accounts for roughly 50%.

An Indicator System for Assessing Soil Erosion in the Loess Plateau Gully Regions:A Case Study in the Wangdonggou Watershed,China

The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.

A Quantification of the Effects of Erosion on the Productivity of Purple Soils

Research on the effects of soil erosion on soil productivity has attracted increasing attention.Purple soil is one of the main soil types in China and plays an important role in the national economy.However,the relationship between erosion and the productivity of purple soils has not been well studied.The purpose of this research was to determine if soil depth,which is dependent on the rate of erosion,has an influence on crop yield and growth.Plot and pot experiments at different soil depths were performed.Results indicate that soils from different parental materials had different growth features and crop yields due to the differential fertility of the derived soils.The yield reduction rate increases exponentially with the depth of eroded soil(level of erosion).The yield reduction rate per unit eroded soil horizon(10 cm) is approximately 10.5% for maize and wheat.

The effects of vegetation on runoff and soil loss:Multidimensional structure analysis and scale characteristics

This review summarizes the effects of vegetation on runoff and soil loss in three dimensions: vertical vegetation structures(aboveground vegetation cover, surface litter layer and underground roots), plant diversity, vegetation patterns and their scale characteristics. Quantitative relationships between vegetation factors with runoff and soil loss are described. A framework for describing relationships involving vegetation, erosion and scale is proposed. The relative importance of each vegetation dimension for various erosion processes changes across scales. With the development of erosion features(i.e., splash, interrill, rill and gully), the main factor of vertical vegetation structures in controlling runoff and soil loss changes from aboveground biomass to roots. Plant diversity levels are correlated with vertical vegetation structures and play a key role at small scales, while vegetation patterns also maintain a critical function across scales(i.e., patch, slope, catchment and basin/region). Several topics for future study are proposed in this review, such as to determine efficient vegetation architectures for ecological restoration, to consider the dynamics of vegetation patterns, and to identify the interactions involving the three dimensions of vegetation.

Linking vegetation cover patterns to hydrological responses using two process-based pattern indices at the plot scale

Vegetation cover pattern is one of the factors controlling hydrological processes. Spatially distributed models are the primary tools previously applied to document the effect of vegetation cover patterns on runoff and soil erosion. Models provide precise estimations of runoff and sediment yields for a given vegetation cover pattern. However, difficulties in parameterization and the problematic explanation of the causes of runoff and sedimentation rates variation weaken prediction capability of these models. Landscape pattern analysis employing pattern indices based on runoff and soil erosion mechanism provides new tools for finding a solution. In this study, the vegetation cover pattern was linked with runoff and soil erosion by two previously de- veloped pattern indices, which were modified in this study, the Directional Leakiness Index （DL[） and Flowlength. Although they use different formats, both indices involve connectivity of sources ,areas （interpatch bare areas）. The indices were revised by bringing in the functional heterogeneity of the plant cover types and the landscape position. Using both artificial and field verified vegetation cover maps, observed runoff and sediment production on experiment plots, we tested the indices＇ efficiency and compared the indices with their antecedents. The results illustrate that the modified indices are more effective in indicating runoff at the plot/hillslope scale than their antecedents. However, sediment export levels are not provided by the modified indices. This can be attributed to multi-factor interaction on the hydrological process, the feedback mechanism between the hydrological function of cover patterns and threshold phenomena in hydrological processes.