Remote Sensing Monitoring Of Soil Erosion In Fujian Province

Soil and water loss(soil erosion)has become an important form of a threat to human ecological security.Based on remote sensing images as the main data source,this paper combined with the rainfall data,soil data,terrain data and field investigation data,taking the dynamic monitoring and analysis on the soil erosion in Fujian province during 1990,2000,2010.The main content including as follows:(1)Remote sensing classification of land use/cover.We completed the rapid extraction of land use/cover in Fujian province in 1990,2000,2010 periods by using the methods of hierarchical information extraction and constructing characteristic index of various project such as water,vegetation,city,bare land and so on.The result shows that woodland is the main land use/cover type in Fujian province,which accounts for more than 70%.The area of farmland and impervious surface has rised during 1990 to 2010,while the bare land has changed greatly under the influence of other factors.(2)Remote sensing estimation of vegetation coverage.Bringing in NDVI products with low spatial resolution,and putting forward a normalized processing seasonal NDVI method on TM images in large area,and estimating the vegetation coverage of Fujian province from 1990 to 2010 by using the normalized NDVI and dimidiate pixel model.The result shows that the method well eliminated the spatial heterogeneity through NDVI normalization seasonal processing on TM images in Fujian province.The vegetation coverage condition in Fujian province is fine,and its spatial distribution is roughly the same.The medium high and above vegetation coverage area has increased during 1990 to 2010,while low and medium low vegetation coverage has decreased significantly.(3)Intensity assessment of soil erosion based on USLE.An estimation method which ppropriated for the southern red soil region factors,was used to complete the calculation of the soil erosion modulus in Fujian province in 1990-2010 three periods.The estimates in conformity with the statistical data and field survey data in general,and also meet application requirements.(4)Variation analysis on the soil erosion intensity of Fujian province.Estimated soil erosion intensity in Fujian province in 1990-2010 three periods based on the USLE model,analyzed its temporal and spatial variation characteristics.The result shows that:from 1990 to 2010 the soil erosion area reduced gradually,and the soil erosion intensity concentrated in mild mainly;from the point of view of spatial distribution,soil erosion turned better gradually,which mainly transformed within non/micro degree and mild/moderate degree.From 2000 to 2010,the soil erosion degree took a turn for the better in Fuzhou,Putian,Quanzhou,Xiamen and Ningde.Meanwhile from 1990 to 2000,the soil erosion degree was to improve local area and the local deterioration in Zhangzhou,Nanping,Sanming,and Longyan.From 1990 to 2010,the soil erosion area of 22 main repaired county gradually reduce on the whole.Changting,Ninghua,and Yongtai give priority to in order to improve,meanwhile Anxi,Jianou and Qingliu is given priority to with deterioration.In 1990-2000,Anxi and Qingliu give priority to in order to improve.From 2000 to 2010,Pinghe and Zhenghe has improved mainly.The changes of soil and water loss in Fujian province are mainly affected by policy,economy and population factors.As policy factors have obvious infect on the soil and water loss in Changting,soil and water loss has been improved well,while affected by economic factors,soil and water loss in Anxi,Jianou and Jianning continues to worsen.