Surface roughness coefficient of forest watershed in the Three Gorges Region.

The surface roughness coefficients of 11 typical stands were quantified by using the Manning Formula for field experiments during the year 2002 and 2003 in Xiangshuixi watershed, Three Gorges Region,at Jiangjin City of Chongqing Municipality. The results show that the values of the surface roughness coefficient vary from 0.018 2 to 0.257 5. The minimum value is in the Castanea mollissima Bl. forest and the maximum value in the mixed forest of Cunninghamia lanceolata with Pinus massoniana and broad-leaved trees. The order of surface roughness coefficient of 11 stands from high to low is as follows: mixed forest of Cunninghamia lanceolata with Pinus massoniana and broad-leaved trees, mixed forest of Cephalotaxus fortunei Hook. with Pinus massoniana and broad-leaved trees, pure forest of Lithocarpus glaber(Thunb.)Nakai, pure forest of Cryptpomeria fortunei Hooibrenk, mixed forest of Pinus massoniana and broad-leaved trees, mixed forest of C.fortunei Hooibrenk and Phyllostachys pubescens Maze, pure forest of Cephalotaxus fortunei Hook., wild land, Phyllostachys pubescens Maze forest, pure forest of Cunninghamia lanceolata and finally pure forest of Castanea mollissima Bl.