Research On Sampling Survey Method Of Soil Erosion And Water Loss In Typical County In The West Of Henan

Soil erosion and water loss is a comprehensive environmental problem, and the status and changes affect the development of regional social economy directly, the input of control measures and the changes of ecological environment. Therefore, it is of great significance to carry out regular monitoring of soil erosion for the development of soil and water conservation and the evaluation about the effectiveness of soil and water loss prevention and control. In order to meet the needs of soil erosion and water loss social bulletin and the development of the society, grasp the regional soil erosion and dynamic changes in the situation timely and effectively, this study choose Songxian which is the typical in the west of Henan province as the research object, based on topography, remote sensing(1998,2009), collected data, other basic information, relying on ERDAS,Arc GIS and ENVI technology platform, to explore soil erosion monitoring technique and methods in county scale in the west of Henan. The main results are as follows:(1) To explore the spatial heterogeneity region division and soil and water loss monitoring methods, the study has constructed the soil and water loss and the main impact factor dataset in the study area, mastered the characteristics and spatial distribution of regional soil and water loss and its main influencing factors, analyzed the dynamic change characteristics, direction and the related reason.In terms of the slope, the overall slope is steep, and the proportion of the steep slope and the above can reach 71.99%. From the perspective of land use, the forest land accounts for the largest proportion(70.46%) which is in the middle and low mountain area, followed by the cultivated land(23.43%)in hilly areas. From 1998 to 2009, the cultivated land reduced, while forest land, residential and industrial land increasedand the change about other land us e types is not significant. In vegetation coverage, it is mostly in high FVC. In the period, the high FVC and high- middle FVC area has increased significantly, while the middle FVC and low- middle FVC reduced significantly, and low FVC without significant changes.The primary type of soil erosion is water erosion, mainly in moderate erosion. In the period, soil erosion area has reduced and moderate erosion area has reduced, overall, the soil erosion showed a decreasing trend in Songxian.(2) The study put forward and define the concept and connotation of the prone, volatile area, heterogeneous minimum unit; divided the prone areas and the volatile area based on the combination of quantitative and qualitative indicators, spatial analysis and qualitative adjustment; explored the construction and optimization of hetero geneous minimum unit on the basis of the combination of the three factors of comprehensive evaluation method.The soil erosion prone area mainly involves the integrated area where is mainly in hills and low mountains, more than 2°, lower than high FVC or high- middle FVC, with frequent and intense anthropogenic disturbances, which accounts for 62.85% of the county area. The volatile area is the area which is mainly related to the change of soil erosion caused by the change of land use, water conservation measures, vegetation condition and other factors, accounting for 50.91% of the prone area and accounting for 32% of the county area; within the scope of the soil erosion prone areas, constructed 6863 initial heterogeneous minimum unit which is mainly distributed in 10-40hm2, after optimizing treatment, 3862 different units were obtained, concentrated in the range of 30 to 80 hm2.(3) Based on the principle of statistics, the study explores the monitoring method which is combined sampling investigation with comprehensive evaluation method, and applies it to soil erosion sampling survey monitoring in country scale. And the study use double precision(sampling accuracy and extrapolation accuracy) and double index(micro degree erosion accuracy and the fitting accuracy of erosion intensity at all levels) to verified the feasibility of the method and the accuracy of the reliability.Studied the influence on the accuracy of the monitoring from the different heterogeneity minimum unit area, different regions, different sampling design and so on, the study designes four kinds of sampling plan namely sampling based on the heterogeneity minimum unit of the prone area, sampling based on the optimization heterogeneity minimum unit of the prone area, sampling based on the optimization heterogeneity minimum unit of the volatile area, unequal probability sampling based on the optimization heterogeneity minimum unit of the volatile area. The extrapolation accuracy(93.69%), the fitting accuracy(96.31%) of prone area, and the monitoring accuracy(93.01%),the fitting accuracy(92.73%) of the county,which are belong to the sampling based on the optimization heterogeneity minimum unit of the volatile area, were higher than other sampling schemes, therefore, this study determined the method as the optimal monitoring method and established the corresponding process of soil and water loss monitoring.The accuracy of soil erosion monitoring is affected by the uniformity of the minimum unit area, but it can improve the accuracy(89.52%,89.44%,88.78%) and meet the demand of the monitoring after optimization.Although the sampling is random, but multiple sampling results show the sampling accuracy,the extrapolation accuracy,the fitting accuracy has stability and reproducibility, the sampling accuracy greater than 80%, and the accuracy of extrapolation and fitting is more than 90%.