Production and construction projects generate engineering accumulation including
waste dump, gangue field, tailings impoundment during construction and production
process. If soil and water conservation lack, soil erosion on these engineering accumulation
are serious. To explore the effective soil and water conservation measures, standard runoff
plots which are 20 meters long and 5 miters wide were be constructed. Effects and
mechanism of hedgerows on sediment erosion of engineering accumulation was studied by
using runoff scouring experiment under three flow discharges(35, 45, 55L/min) and three
slope gradients(24°, 28°, 32°) . The results indicated that:
（1）Runoff and sediment yield of control plot and hedgerows plot increased with
increasing of runoff discharge and gradient. Runoff yield of hedgerows can reduce runoff
and sediment yield effectively: ①Runoff reduction benefit that reaches 4%~40% increase
with increasing of plot gradient. But the relationship between runoff reduction benefit and
runoff discharge is not simple linear correlativity, it increases first then decreases as
increasing of runoff discharge. ②Sediment reduction benefit of hedgerows which is
15%~45% decreases with increasing of runoff discharge and gradient.
（2）Runoff rate and sediment rate of control plot and hedgerows plot increase with
increasing gradient and runoff discharge. Varying tendency of runoff rate with the time
rapidly increases in early then level off. While sediment rate rapidly increases in early then
dramatic decline in later, even it in the end of the time is less than it in the beginning under
large runoff discharge(45、55L/min). Runoff rate and sediment rate of hedgerows plot is
less than it of control plot. Outflow moment of hedgerows plot is delayed for 2~10min than
control plot. Sediment rate of hedgerows plot is less than it of control plot in early stage,
then the difference is more and more smaller in later stage even the former exceed the later.
（3）Rill erosion amount has the greatest proportion in first section of slope, which is at least 40%. Rill erosion of the upper slope shows a trend of decrease after the first
increase with increasing of gradient. Rill erosion has the greater proportion with increasing
of runoff discharge, which shows that rill erosion improve downwards. Protective effect of
hedgerows is better for lower slope and rill erosion is limited to upper slope by hedgerows.
Hedgerows have more significant impact on rill distribution of 24° and 32° plot.
（4）The content of sand grains in sediment increase gradually while the content of
clay particles reduce with increasing gradient of and runoff discharge. Compared with
control plot, sand grains content decreases while silt and clay particles content increases in
sediment of Hedgerows plot. This results show that hedgerows have obvious intercept
capability for sand grains. sand grains can be an index to evaluate the effect of hedgerows
to slope erosion.
（5）Hedgerows reduce the soil detachment rate from 3~10g·m -2 ·s -1 to 1.5~8g·m -2 ·s -1 ,
and decrease the runoff shear stress 4~8N·m -2 to 2.5~6N·m -2 , increase critical shear stress
and critical stream power by 0.25 and 5 times. Hedgerows reduce the water erosion
degrees by weaken the energy and erosion dynamic of slope runoff.
（6）Erosion control capacity of a specific hedgerows has a critical value over time.
The relationship between erosion control and scour time can be fit by quadratic function.
The maximum value of sediment reduction accumulated amount appeared later than 26th
min, and it would appear in advance with increasing gradient of and runoff discharge. The
direct cause for time limit of hedgerows controlling erosion is the sequential variation of
the runoff sediment concentration. The ratio of sediment concentration to sediment
carrying capacity show the source-sink relation of hedgerows and runoff which is
underlying cause that erosion control capacity has critical value.
Key words: engineering accumulation; hedgerows; flow discharges; erosion control;