Study on the vegetation coverage dynamic change of songhuajiang watershed based on RS and GIS

The vegetation coverage was generated by processing the Landsat TM/ ETM+ images of 1989, 1995 and 2001 using remote sensing and geographical information systems technology and estimating NDVI of Songhuajiang river. To analyze the changes of vegetation coverage over time, the vegetation coverage was overlaid at the watershed scale with the support of spatial analysis of ArcGIS 9.2. The results showed that the NDVI value was 0.1–0.2 in 1989–1995a and 0.4–0.5 in 1995–2001a when the increment of pixel number and area was greatest meanwhile the NDVI value was −1 in 1989–1995a and 0.1–0.2 in 1995–2001a when the reduction was greatest. The NDVI value was increased in the region focused on the general vegetation coverage from 1989–2001a and decreased mainly in the region with high vegetation coverage in 1989–1995, but the greatest reduction of value was in the region with low vegetation in 1995–2001a.