In order to study the dynamic characteristics of overland flow under the combined effects of rigid vegetation coverage and surface roughness

the hydraulic flume experiment was carried out. The experiment included 10 discharges (0.33～1.95 m3/h)

five different coverage levels (0

0.5%

1%

1.5%

2%)

four different surface roughness levels (Ks=0.01

0.18

0.25

0.38 mm) and one angle level (15°). The results show that: (1) The flow velocity fluctuated from 0.06 to 0.59 m/s

the average flow velocity was negatively correlated with the vegetation coverage and the surface roughness. When the vegetation coverage increased

the average flow velocity which increased with the discharge would reduce the level of increase. The correction factor (α) coefficient had a positive correlation with the vegetation coverage

and a negative correlation with the surface roughness. (2) The Reynolds number ranged 153~910

the flow pattern was mainly concentrated in the transition zone and the virtual laminar zone

and the flow regime was mainly concentrated in the rapids zone. With the increases of vegetation coverage and surface roughness

the flow pattern gradually extended to the slack zone (Fr＜1). (3) The total flow resistance coefficient was exponential with Reynolds number

and positively correlated with surface roughness and vegetation coverage. (4) The influence index of resistance showed that when the flow rate was less than 1.05 m3/h

the influence of surface roughness was greater than the vegetation coverage

otherwise the vegetation coverage became into the prominence. The total resistance was significantly different with the linear superposition value of grain resistance and surface object resistance through t-test

indicating that the linear superposition could not be used to calculate the total resistance

when the grain resistance and surface object resistance existed.