Surface roughness coefficient and its influencing factors on the slope of typical forests in Jinyun mountain of Chongqing

Surface roughness coefficients on the slope of forestland in Jinyun mountain of Chongqing by using the Manning Formula are conducted based on the measured field experiments data in 4 typical forests(Pinus massoniana,mixed with Pinus massoniana and broadleaf trees,broadleaf forest and Phyllostachys pubescens),compared to crop-land,in Jinyun mountain,Chongqing City of the Three Gorges Reservoir Area in April 2008.The results show that the values n of the surface roughness coefficient vary from 0.007 9 to 0.270 4.The value n of Pinus massoniana is minimum and the value n of the mixed with Pinus massoniana and broadleaf trees is maximum.The descending order of surface roughness coefficient of 4 typical forests is as follows: mixed with Pinus massoniana and broadleaf trees,broadleaf forest,Phyllostachys pubescens,Pinus massoniana.The relationships between surface roughness coefficient and litter depth is shown as linear relationship,the formula of surface roughness coefficient(y) and litter depth(x) is: y=0.0205e^0.5436x,R₂ is 0.9237 respectively,and there is a logarithmic relationship between surface roughness coefficient(x) and infiltration capacity of surface water(y),the formula is: y=37.25lnx+188.47,R² is 0.7782.The infiltration capacity of surface water increases with the increase of surface roughness coefficient.