In order to calculate the contribution coefficient of runoff depth on the main land use types in the Taoer River basin, multiobjective decision-making method is used [29, 37, 38].
When the multiobjective decision-making method is used to calculate the contribution coefficient of runoff depth, the basic objective function can be expressed by the annual average runoff depth formula, as shown in formula (1):
represent the contribution coefficient of runoff depth in cultivated land ([A.sub.x]), woodland ([F.sub.x]), grassland ([P.sub.x]), and construction land ([U.sub.x]) in each unit area ([km.sup.2]), respectively.
where [DELTA]P and [DELTA][E.sub.0] are the changes in the precipitation and potential evapotranspiration, respectively; [beta] and [gamma] are the sensitivity coefficient of runoff
to precipitation and potential evapotranspiration, respectively:
SRI can be interpreted as follows: when the variation coefficient of precipitation increased, but the variation coefficient of runoff was not equally increased, then the streamflow regulation index became smaller, so the ability of the streamflow regulation of the watershed was increased; otherwise, it was decreased.
The variation coefficient of runoff and rainfall is provided in Figure 7.
Regardless of changes in CN, and the coefficient of runoff, development of water erosion, especially surface erosion, rill erosion, gully erosion and piping erosion were visible in the visit of the area, which can attribute their recent development to their increase amount of surface runoff and discharge, although this may be arise from climate changes, natural factors and other factors.
, reducing permeability and maintenance of soil surface and consequently increase in the coefficient of runoff and afterwards increase in surface runoff.
The coefficient of runoff
for the equipment and solids staging area was c=0.90.
[beta] is the sensitivity coefficient of runoff
to precipitation, and [gamma] is the sensitivity coefficient to potential evapotranspiration.
The variation coefficient of runoff
is the biggest at the beginning of the 21st century, which shows that the runoff in this period has a dramatic change and is greatly influenced by human activities.