~ ~ ~ PURPOSE ~ ~ ~
this subroutine predicts daily soil loss caused by water erosion
using the modified universal soil loss equation
~ ~ ~ INCOMING VARIABLES ~ ~ ~
name |units |definition
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
cvm(:) |none |natural log of USLE_C (the minimum value
|of the USLE C factor for the land cover)
hru_km(:) |km**2 |area of HRU in square kilometers
qp_cms |m^3/s |peak runoff rate
surfq(:) |mm H2O |surface runoff for the day in HRU
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ OUTGOING VARIABLES ~ ~ ~
name |units |definition
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
cklsp(:) |
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ LOCAL DEFINITIONS ~ ~ ~
name |units |definition
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
bio_frcov | |fraction of cover by biomass - adjusted for
canopy height
grcov_fr | |fraction of cover by biomass as function of lai
rsd_frcov | |fraction of cover by residue
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ SUBROUTINES/FUNCTIONS CALLED ~ ~ ~
Intrinsic: Exp
~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~
initialize variables compute sediment yield with musle - t this is the form of MUSLE in APEX documentation - same results as swat equation above ! t/ha
adjust sediment yield for protection of snow cover Particle size distribution of sediment yield
compute erosion with usle (written to output for comparison) erosion output variables sum daily erosion output