**Other Abstract** | Various production and construction projects are increasingly implemented along with
increased investment in China's infrastructure construction projects. In the process of
construction, plenty of vegetation is destroyed and surface and underground soils are
disturbed, detached and removed, which has caused serious man-made soil erosion and made
eco-environmental problems to become severe year by year. Because of illegal heaping and
random dumping without any protective measure, massive waste soils and residues, i.e.,
engineering accumulations, become the most serious places subject to soil and water loss and
the main sediment origins for the newly-added soil and water loss by human, which severely
deteriorates local eco-environment. In order to construct a soil and water loss calculation
model suitable for production and construction projects in China, it is essential to refer to the
ideas involved in the Universal Soil Loss Equation (USLE) and revise such factors as soil
erodibility, slope steepness, slope length and rainfall erosivity. At present, research on these
aspects still has many works to do in China. In this study, by taking the engineering
accumulation of production and construction projects in the loess area as the research object,
runoff yield, sediment yield and hydrodynamics on indoor simulated engineering
accumulation were focused through an artificially simulated rainfall experiment. Specific
objectives were to understand the mechanisms of soil erosion and the processes of soil and
water loss and find the relational expression and the method to define fixed value for slope
steepness factor (S) incorporated in the soil and water loss calculation model. Our study may
provide a scientific basis for the calculation model and the supervision and law enforcement by governmental departments in charge. The study is of important significance in science and
practical values in application. The main conclusions are as follow:
(1) Under the condition of different soil textures, runoff rate and sediment transport rate
are linear and power functions of rainfall amount, respectively. Runoff rate has a linear
relation with rainfall amount and slope steepness, while sediment transport rate, a power
relation. The relationship between sediment transport rate and runoff rate can be described
using exponential function.
(2) Under the condition of different rainfall amounts, runoff rate has a linear relation
with slope steepness and a complex linear function with slope steepness and soil texture. For
rainfall amounts of 45, 90 and 112.5 mm, sediment transport rate has significant complex
liner relation with slope steepness and soil texture, while for rainfall amounts of 90 and 112.5
mm, there is a significant exponential relationship between sediment transport rate and soil
texture.
(3) Under different slope steepnesses, runoff rate and sediment transport rate are linear
and power functions of rainfall amount, respectively, but have no correlation with soil texture.
Runoff rate and sediment transport rate are complex linear function of rainfall amount and
soil texture, respectively. There is an exponential relationship between sediment transport rate
and runoff rate.
(4) Runoff rate and sediment transport rate are significant linear and exponential
functions of rainfall amount, respectively, if slope steepness and soil texture are not taken into
account. Runoff rate and sediment transport rate are complex linear function of rainfall
amount, slope steepness and soil texture.
(5) For the same soil texture, both runoff shear stress and stream power increase with
increased rainfall amount. Unit stream power increases with increased rainfall amount and
slope steepness. For the same slope steepness, both runoff shear stress and stream power
increase with increased rainfall amount. Rainfall amount is the main factor affecting runoff
shear stress and stream power. For the same rainfall amount, unit stream power increases with
slope steepness and slope steepness has the greatest effect on unit stream power.
(6) Runoff shear stress is complex linear function of rainfall amount, slope steepness and
soil texture, while stream power and unit stream power are complex liner function of rainfall
amount, slope steepness and soil texture. The relationships of soil detachment rate with runoff
shear stress, stream power and rainfall amount can be described using exponential function,
respectively. Soil detachment rate is quadratic function of unit stream power and the Froude
number (Fr), and power function of the Reynolds number (Re) and resistance coefficient (f),
respectively. The optimal curve fittings for the relationships between soil detachment rate and the hydrodynamic parameters are in the descendant order of rainfall amount, stream power,
unit stream power, Fr, f, runoff shear stress and Re. Soil detachment rate is complex liner
function of rainfall amount, slope steepness and soil texture.
(7) For the first time, the standard plot and slope steepness factor used in the water
erosion calculation model are defined in combination with the characteristics of the
engineering accumulation. The standard plot adopted for the research on soil and water losses
from various engineering accumulations in China is defined as the bare plot with a length of 5
m and a slope steepness of 35º. The slope steepness factor S is defined as the ratio of soil loss
from a specific engineering accumulation to that from the engineering accumulation of 35º
slope steepness, when other conditions are identical.
(8) A check spreadsheet of the S values for the slope steepnesses of 15º to 44 º is
established using the power and trigonometric equations of slope steepness factor obtained by
regression fittings.
Keywords: production and contribution project, engineering accumulation, standard plot,
slope steepness factor, hydrodynamic parameters |

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