Monitoring Of Soil Erosion And Eco-Security Assessment In Changting County

Soil erosion is one of ecology risks. This paper focuses on soil erosion monitoring in county ChangTing from 1994 to 2003, whose data are mainly from remote sensing image, basic geographic data and the field-work material. Moreover, the evaluation of eco-security and the application of 3S technologies in eco-security evaluation on soil erosion area are finished. (!) Vegetation Fraction Estimation. VBSI vegetation index that can decrease the influence from shadow and soil interference is proposed, based on analysis of remote sensing image spectra and the related researches. Furthermore, the application and comparison of mixed pixel model and empiric model are implemented. The results show that: VBSI may decrease the error of vegetation fraction resulted from the area of image shadow, and the error is 50% less than that from NDVI. Compared with empiric model, the mixed pixel model has similar accuracy, and it is cheap and better to apply to images from different phases. The vegetation attribution is good and the percentage of high vegetation fraction is improved from 71.6% to 76.5%. (2) Soil Erosion Monitoring. Soil erosion monitoring based on "Standard of Surface Erosion"and USLE are applied to research area. The results show that: the monitor method based on USLE has better theory basics and achieves better investigation fruits. The mean slope of soil erosion area is mainly 7-25 degree, and the critical mean vegetation fraction is about 0.7. The percentages of soil erosion in 1994 and 2003 are 24.6% and 18.9% respectively. Soil erosion attributes in the middle and the south-east of Changting, especially along Tingjiang River. After nearly ten years mankind's efforts, the percentage of soil erosion is declined 5.6%, and the Shannon-Wiener index of soil erosion is descended from 1.16 to 1.01. With reduction of soil erosion, the mean slope and vegetation fraction related with the same soil erosion degree are fallen. (3) Eco-security Evaluation The PSR-AHP framework and eco-security evaluation of research area are completed, supported by the remote sensing monitor fruits and social economic statistics. The results show that the weights from AHP method have sufficient mathematic support and embody ecology meanings. After about ten year efforts, the eco-security index is increased from 0.4206 to 0.5795, which indicates the eco-security situation of research area is better and better. From the ascending of mankind's respond index (0.0819->0.1779), we can conclude that the government had being taken some effective measures on soil erosion and water preservation.