In order to reveal the effect of surface land fluctuation on the overland flow under the micro-scale conditions

through the field artificial rainfall simulation experiment

the influence of five micro topography types on the overland flow were analyzed under 60

90 and 120 mm/h rainfall intensity for 90 min. The five micro topography types were smooth

single mound

single depression

intervals mound and depression

continuous mound and depression. The results showed that:(1) Compared with the smooth group

the single mound

single depression and mixed fluctuation mode all delayed the initial flow generation time

and the time followed the order of smooth group < single mound group < single depression group < intervals mound and depression group < continuous mound and depression group. (2) The existence of mounds and depressions reduced the average flow velocity

among which the average flow velocity of continuous mound and depression group was the smallest. (3) Under the three kinds of rain intensity

there were three kinds of catchment form of overland flow on slope (branch shape

parallel shape and feathery shape) in five kinds of microtopography

among which catchment forms of the smooth group and the intervals mound and depression group were both branch

the catchment forms of the single mound group and the single depression group were feathery and branch

while it was mainly feathery shape in single mound group and branch in single depression group. The catchment forms of the continuous mound and depression group were mainly parallel shape. (4) Under the three kinds of rainfall intensity

the confluence density and runoff frequency showed the same change rule

which was the confluence density and runoff frequency of smooth group and single mound group decreased at first

and then increased with the increasing of rainfall intensity

meanwhile

the confluence density and runoff frequency of single depression group and combination of mound sand depressions groups increased with the increasing of rainfall intensity. The differences in the confluence density and the runoff frequency among the five microtopography were the smallest under the rainfall intensity of 90 mm/h. The results of this study revealed the influence of different surface fluctuation types on the overland flow of sloping farmland

which was helpful to further study the mechanism of soil erosion.