The research work is based on the original landuse map (1:10 000) of Hongmenchuan basin and combined with remote sensing images of the basin in 1990

1995

2000

and 2005. Landuse maps of the four periods were made with the support of GIS software and the change in the spatial pattern of shelter was found with the help of ArcView. At the same time

using the data of daily runoff of Hongmenchuan basin from 1990 to 2006

the response relationship between the change in the structure of shelter forest and the local runoff was studied. Results showed that the total area of shelter forest and the areas of various forest types did not change obviously. Shelter forest was dominated by highwood

accounting for more than 80%. With a little change of precipitation

annual runoff had a declined tendency from 3.00×107 m3 in 1990 to less than 1.00×107 m3 after 2000. The main reason was that shelter forest had played a role in flood reduction. However

the conclusion that the structure change of shelter forest had exerted an important influence on runoff can not be reached at present.