Landscape Entropy Model Application In The Monitoring And Assessment Of Sandy Land

Due to the arid climate, water deficiency and soil erosion, northern China is confronted with several severe challenges, among which land sandification is the main cause for slowing the local economy development and the sand storm frequently raiding Beijing, capital of People's Republic of China. As the first step for sandy land control, sandy land monitoring can provide effective technical support for the decision and sandy land management project. GIS techniques are characterized for its rich information and direct, macro and exact vision, and therefore are an effective tool for sandy land monitoring.Fengning County, a typical farming-grazing transitional region located in Chengde city, is chosen to be the typical research area and careful field investigation and spectral measurement were taken there: Multi-temporal satellite imagery was selected on which integrated sandy land monitoring system was based.(1) Sandy land monitoring For the sandy land information extraction, this study chooses appropriate imagery which is able to display maximum spectral difference. Based on elaborate field spectral data and field investigation data, an index was introduced for the sandy land information extraction, and results show the accuracy reaches up to 90 percent.(2) Sandy land level assessment Unlike the traditional assessment which chooses vegetation indicator to represent the sandy land condition, this thesis attemptes to integrate the dynamic vegetation indicator with fixed indicators (e. g soil texture)to assess the current sandy land level. Afterwards, three indicator images are hierarchies and then the composite image is used to make the sandy land level assessment by means of image overlapped method.(3) Application of comprehensive assessment index About the comprehensive quantity index, many researcher often bring out some threshold values in different scales to assess the degree of sandy, such as Zhu Zhenda,...