HSFP
The HSFP soil erosion model requires the following land use specific model parameters (hspf_table):
Table 41: Hspf_table
-99
1
2
3
1
0.65
0.03
0
2
0.5
0.2
0
3
0.35
0.5
0
…
…
…
…
Ground cover is similar to all other soil erosion models, specified per land use class. The soil scour detachment coefficient (KGER) is a model parameter that is a soil erodibility parameter for detachment by runoff. The “no erosion” column (0 or 1) prevents erosion from happening, for instance for water and paved land use classes.
The P-factor map indicates the support practice factor, which indicates how conservation measures reduce soil erosion, which factor is often considered to be 1.
The rainfall detachment coefficient KRER is similar to the USLE K-factor. The Wischmeier et al. (1971) formulations are used (see section 2.8) when this is left empty. In that case, a sand, clay and organic matter map should be provided in the PEDOTRANSFER section of the config file (even when the pedotransferfunctions are not used (i.e. if PedotransferFLAG = 0). The rainfall detachment exponent JRER is an exponent in the detachment by raindrop impact formulation.
Similar model parameters exist for the washoff detachment, i.e. KSER and JSER, and for scour detachment, i.e. KGER and JRER. The soil scour detachment KGER should be left empty when the land use specific values are provided in hspf_table.
The fraction by which detached sediment storage decreases per time step is defined by AFFIX.
Table 42: Model parameters
Ground cover
CR
-
0-1
Soil scour detachment
KGER
-
0.01-0.5
No erosion
0 or 1
Support practice factor
SMPF
-
0-1
Rainfall detachment coefficient
KRER
-
0.14-0.45
Rainfall detachment exponent
JRER
-
1.5-3
Washoff detachment coefficient
KSER
-
0.1-5
Washoff detachment exponent
JSER
-
1.5-2.5
Soil scour detachment coefficient
KGER
-
0.01-0.5
Soil scour detachment exponent
JGER
-
1-2
Fraction of sediment storage decrease
AFFIX
-
0.05
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