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Figure 1: Spatial distribution of land use and monitoring sites of buffer/
detention landscape structures. Abbreviations: SDs, stone dams;
RGD, roadside grassed ditch; GFS, grassed filter strip; DPs, dry
ponds; RBZ, riparian buffer zone
Calculation of the sediment and P-pollutants removal rate
The mass removal rate of sediment and P-pollutants of single buffer/detention
structure or the whole system they constituted can be calculated from flow-weighted
mean concentration and run-off volume of waterflow when it enters and leaves the
system or structure. The formula can be established as follows:
MPI = ∑QPIiCPIi
MPO = ∑QPOiCPOi
MPT = ∑QPTiCPTi
R = [1-M PO / (M PI + M PT )]x100%
in which QPIi, QPOi and QPTi are inflow, outflow and tributary flow volume of the
whole system or single structure (m 3 ); CPIi, CPOi and CPTi are mean pollutants
concentration in inflow, outflow and tributary flow of the whole system or single
structure (g/L or mg/L); MPIi, MPOi and MPTi are total pollutants mass in inflow,
outflow and tributary flow of the whole system or single structure (kg); i is buffer/
detention structure number, from 1 to 5; R is the removal rate of the whole system
or single structure.
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