兴国县土壤侵蚀变化的遥感监测与分析

兴国县是南方红壤丘陵区水土流失最严重的地区之一,近20年的综合治理成效显著。为分析该时期县域内水土流失的变化趋势,并掌握其目前的水土流失状况,本文选用1987、1994和2000年的TM影像,采用基于NDVI 的动态监测和影像分类相结合的方法.对江西兴国县近20年水土流失的情况进行分析,定性与定量地反映兴国县水土流失的时空变化趋势,并结合地形因素进行交叉分析,获取水土流失的空间分布规律。兴国县水土流失变化分析结果表明:在水土流失面积方面,这3年中均呈减少趋势;在空间分布上,中南部和东部部分地区流失强度下降幅度较大,强度明显加剧的区域较少,除西南部的部分地区外,仅在县境边缘有零星分布。目前,水土流失主要分布在海拔500m以下和坡度20°以下的地区。

Changes Detection and Analysis of Soil Erosion Based in Xingguo of Jiangxi Province

Xingguo county is one of the areas suffering from most serious soil erosion in the hilly red soil region of southern China. In the recent years, the status has been changing positively by taking different methods to prevent soil and water losses. The main purpose of this paper is to master the trend of soil erosion during this period and soil erosion status in this county. It mainly introduces the dynamic monitoring method based on NDVI in combination with image classification to analyze soil erosion changes in the past 20 years. After rectifying TM data of 1987,1994 and 2000, thresholds are specified considering the assistant information from NDVI different histogram plots. Accordingly, the changes mask image is made available and used in classification. Then, to check the accuracy, classification result is contrasted with field samples. Finally, this paper concludes that the soil eroded area kept decreasing in the past 20 years. For the spatial distribution of soil erosion, the decreased soil eroded area are scattered around central part and some areas of the eastern part of Xingguo; the areas suffering from deteriorated soil erosion were limited, except for some places scattering around the county borders and the southwestern part of Xingguo. At present, the areas related to soil and water loss are mainly distributed in the places with an elevation below 500m and slope gradient less than 20.