Research on Grassland Degradation Assessment Model based on ETM+Image——A Case Study in Naqu County of Tibet
基于ETM+影像的草地退化评价模型研究——以西藏自治区那曲县为例

First,the height,coverage and biomass is respectively selected as the single index of ground assessment of grassland degradation based on field survey and systematic random samples,and the ground integrated assessment index is calculated by integrating the height,coverage and biomass.Meanwhile,the remote sensing indices are derived from ETM+ image based on the spectral value of degraded grassland.Second,according to the results of correlation analysis between ground assessment indices and RS assessment indices,the ground integrated assessment index and the spectral index of TM4/TM5 are chosen as the best variables to build the grassland degradation model with linear regression.And the decision coefficient(R2),error of mean square root(RMSE) and relative error are calculated to test the precision of the assessment model.Last,the standards of different degraded level of main grassland types are defined and the grassland degradation map is drawn.In this paper,the grassland degradation model of north Tibet is studied based on the relation between ground assessment indices and remote sensing assessment indices,which provides a new idea for scientific and quick assessment of grassland degradation.