module erosion_default
  
  implicit none

  ! 
  ! Some default values for input to the WEPS' EROSION submodel.
  ! for bare soil.
  !
  ! For more "representative" values of a summer fallow field
  ! during spring and autumn in the Columbia Plateau region, see 
  !
  !  G. Feng and G. Sharratt
  !  Sensitivity analysis of soil and PM10 loss in WEPS using the LHS-OAT method,
  !  Transactions of the American Society of Agricultural Engineers 48(4), 
  !  1409-1420, 2005
  !
  !  G. Feng and B. Sharratt
  !  Validation of WEPS for soil and PM10 loss from agricultural fields 
  !  within the Columbia Plateau of the United States,
  !  Earth Surface Processes and Landforms 32, 743-753, 2007

  ! +++ SOIL SURFACE +++

  ! surface crust fraction (m2/m2)
  real, parameter :: asfcr_default = 0.
  ! surface crust thickness (mm)
  real, parameter :: aszcr_default = 0.
  ! fraction of crusted surface with loose material on top 
  ! of crust (m2/m2)
  real, parameter :: asflos_default = 0.
  ! mass of loose material on top of crust (kg/m2)
  real, parameter :: asmlos_default = 0.
  ! density of soil crust (Mg/m2)
  real, parameter :: asdcr_default = 0.1 !!!1.7
  ! dry crust stability (ln(J/kg))
  real, parameter :: asecr_default = 1.0 !!!1.35
  ! allmaras random roughness (mm)
  real, parameter :: aslrr_default = 10. !!!3.
  ! ridge height (mm)
  real, parameter :: aszrgh_default = 0.0
  ! ridge spacing (mm)
  real, parameter :: asxrgs_default = 0.0
  ! ridge width (mm)
  real, parameter :: asxrgw_default = 0.0
  ! ridge orientation (degrees)
  real, parameter :: asargo_default = 0.0
  ! dike spacing (if no dikes, specify 0.0) (mm)
  real, parameter :: asxdks_default = 0.0
           

  ! ++++ SOIL ++++ |

  ! rock volume in soil layer (m3/m3)
  real, parameter :: asvroc_default = 0.0

  ! ++++ Crop ++++ |

  ! "overall" height of all standing biomass, both crop and 
  ! residue vegetation (meters)
  real, parameter :: abzht_default = 0.0
  ! average height of growing crop (meters)
  real, parameter :: aczht_default = 0.
  ! growing crop stem area index (m2/m2)
   real, parameter :: acrsai_default = 0.0
  ! growing crop leaf area index (m2/m2)
  real, parameter :: acrlai_default = 0.0
  ! residue stem area index (m2/m2)
   real, parameter :: adrsaitot_default = 0.0 !0.03
  ! residue leaf area index (m2/m2)
   real, parameter :: adrlaitot_default = 0.0
  ! Growing crop row spacing (meters)
  ! (use value of 0.0 if not planted in rows, 
  ! e.g. broadcast seeded)
   real, parameter :: acxrow_default = 0.0
  ! specify seed location (0=furrow,1=ridge)
  ! (value doesn't matter if no rideges exist)
  integer, parameter :: ac0rg_default = 0
  ! flat biomass cover (m2/m2)
   real, parameter :: abffcv_default = 0.0 !0.15
  
   ! ++++ HYDROLOGY ++++ |

  ! current surface layer water content (g/g)
  real, parameter :: ahrwc0_default = 0.010


  ! ++++ OTHERS ++++ |

  ! (smooth?) surface aerodynmaic roughness (mm)
  real, parameter :: zo_default = 10.



end module erosion_default