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Variable Infiltration Capacity (VIC)
Macroscale Hydrologic Model
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VIC Soil Parameter File

Soil hydrologic and thermal parameters needed for the different VIC model set-ups are listed below. All columns of the input file must be filled, but certain parameters need only be defined if the full energy or frozen soil models are activated. Red text indicates parameters needed for the energy balance model. Violet text indicates parameters needed for the frozen soil model. Header lines can be added by starting the line with a '#'.

In previous versions certain parameters were read as average values for the entire soil column. In version 4.0 all soil parameter values are now read for all layers. Converting the soil parameter file from older model versions, should simply require copying column average values to separate columns for each soil moisture layer.

To help in understanding this file, an example file has been attached at the bottom of this page.

Column

Variable Name

Units

Number of Values

Description

1

run_cell

N/A

1

1 = Run Grid Cell, 0 = Do Not Run

2

gridcel

N/A

1

Grid cell number

3

lat

degrees

1

Latitude of grid cell

4

lon

degrees

1

Longitude of grid cell

5

infilt

N/A

1

Variable infiltration curve parameter (binfilt)

6

Ds

fraction

1

Fraction of Dsmax where non-linear baseflow begins

7

Dsmax

mm/day

1

Maximum velocity of baseflow

8

Ws

fraction

1

Fraction of maximum soil moisture where non-linear baseflow occurs

9

c

N/A

1

Exponent used in baseflow curve, normally set to 2

10 : (Nlayer+9)

expt

N/A

Nlayer

Exponent n (=3+2/lambda) in Campbell's eqn for hydraulic conductivity, HBH 5.6 (where lambda = soil pore size distribution parameter).

Values should be > 3.0.

(Nlayer+10) :(2*Nlayer+9)

Ksat

mm/day

Nlayer

Saturated hydrologic conductivity

(2*Nlayer+10):(3*Nlayer+9)

phi_s

mm/mm

Nlayer

Soil moisture diffusion parameter

(3*Nlayer+10):(4*Nlayer+9)

init_moist

mm

Nlayer

Initial layer moisture content

(4*Nlayer+10)

elev

m

1

Average elevation of grid cell

(4*Nlayer+11):(5*Nlayer+10)

depth

m

Nlayer

Thickness of each soil moisture layer

(5*Nlayer+11)

avg_T

C

1

Average soil temperature, used as the bottom boundary for soil heat flux solutions

(5*Nlayer+12)

dp

m

1

Soil thermal damping depth (depth at which soil temperature remains constant through the year, ~4 m)

(5*Nlayer+13):(6*Nlayer+12)

bubble

cm

Nlayer

Bubbling pressure of soil

Values should be > 0.0

(6*Nlayer+13):(7*Nlayer+12)

quartz

fraction

Nlayer

Quartz content of soil

(7*Nlayer+13):(8*Nlayer+12)

bulk_density

kg/m3

Nlayer

Bulk density of soil layer

(8*Nlayer+13):(9*Nlayer+12)

soil_density

kg/m3

Nlayer

Soil particle density, normally 2685 kg/m3

(9*Nlayer+13)

off_gmt

hours

1

Time zone offset from GMT

(9*Nlayer+14):(10*Nlayer+13)

Wcr_FRACT

fraction

Nlayer

Fractional soil moisture content at the critical point (~70% of field capacity) (fraction of maximum moisture)

(10*Nlayer+14):(11*Nlayers+13)

Wpwp_FRACT

fraction

Nlayer

Fractional soil moisture content at the wilting point (fraction of maximum moisture)

(11*Nlayer+14)

rough

m

1

Surface roughness of bare soil

(11*Nlayer+15)

snow_rough

m

1

Surface roughness of snowpack

(11*Nlayer+16)

annual_prec

mm

1

Average annual precipitation.

(11*Nlayer+17):(12*Nlayer+16)

resid_moist

fraction

Nlayer

Soil moisture layer residual moisture.

(12*Nlayer+17)

fs_active

1 or 0

1

If set to 1, then frozen soil algorithm is activated for the grid cell. A 0 indicates that frozen soils are not computed even if soil temperatures fall below 0C.

(Optional)

frost_slope

C

1

Slope of uniform distribution of soil temperature (if SPATIAL_FROST == TRUE in the user_def.h file).

(Optional)

depth_full_snow_cover

mm

1

Minimum snow depth for full coverage across the grid cell (if SPATIAL_SNOW == TRUE in the user_def.h file).

(Optional)

initial_ice_content

N/A

1

Initial volumetric ice content in soil (if EXCESS_ICE == TRUE in the user_def.h file).

(Optional)

July_Tavg

C

1

Average July soil temperature, used for treeline computations (if JULY_TAVG_SUPPLIED == TRUE in the global parameter file).

Note: if BASEFLOW is set to NIJSSEN2001 in the global parameter file, VIC will interpret the baseflow parameters Ds, Dsmax, Ws, and c to be the alternative baseflow parameters D1, D2, D3, and D4.

Example Soil Parameter File:

View the example here.

VIC Administrator
Last modified: Mon Aug 31 13:54:23 PDT 2009