The Method Of Vegetation Fraction Estimation By Remote Sensing

Vegetation fraction is a most important indicating to vegetation, and it is one of the most important factors of eroding soil. The purpose of this paper is analyzing and discussing the methods of measuring vegetation fraction, and building the model of quantifying vegetation fraction by remote sensing. The study includes: First, introduce the basic theories, the study status and the developing direction of the methods of measuring vegetation fraction. Then based on the method of dimidiate pixel model, the current model is improved, and the model of deriving vegetation fraction from normalized difference vegetation index (NDVI). The improved model gives a new method of estimating two important parameters of the old model, and the deducing process of the two parameters. For three cases of practice requirement, different schemas of measuring vegetation fraction are designed. To choose a certain schema, there are three factors that should be considered: location of research area, time character of remote sensing data and spatial resolution. The model can be used to many scales remote sensing data. According to actual characters of the research areas: Guanting and Miyun reservoirs, the first schema of improved model is chosen. Then a series of technical route isdesigned, and the methods of realizing the technical route are given. As a part of the soil and water conservation environmental project of Guanting and Miyun reservoir upper reaches area, the vegetation fraction of Guanting and Miyun reservoir valley is estimated using this technical route. By on the spot review of Miyun valley, the result of estimation of vegetation fraction is proved to be valid. The result suggests that using this improved model to estimate vegetation fraction is feasible.