# VIC Vegetation Parameter File

Vegetation parameters needed for the different VIC model set-ups are listed below. Number of vegetation tiles and fraction of grid cell covered must be defined for each grid cell.

## Vegetation Parameter File Format

| Variable Name     | Units     | Description                                   |
|---------------    |-------    |---------------------------------------------  |
| gridcel           | N/A       | Grid cell number                              |
| Nveg              | N/A       | Number of vegetation tiles in the grid cell   |

Repeats for each vegetation tile in the grid cell:

| Variable Name   | Units     | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|---------------  |---------- |   |
| veg_class       | N/A       | Vegetation class identification number (reference index to [vegetation library](VegLib.md)) <br><br>*NOTE 1*: it is common practice to define only one tile for each vegetation class in the grid cell. But this is not strictly necessary. It is OK to define multiple tiles having the same vegetation class. <br><br>*NOTE 2*: As of VIC 4.1.1, if you are simulating lakes, you MUST designate one of the tiles from each grid cell as the tile that contains the lake(s). This designation happens in the [lake parameter file](LakeParam.md). You can either choose an existing tile to host the lakes, or insert a new tile (just make sure that the sum of the tile areas in the grid cell = 1.0). This extra lake/wetland tile may have the same vegetation class as one of the other existing tiles (see NOTE 1).   |
| Cv              | fraction  | Fraction of grid cell covered by vegetation tile                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |

For each vegetation tile, repeats for each defined root zone:

| Variable Name   | Units     | Description                                                             |
|---------------  |---------- |------------------------------------------------------------------------ |
| root_depth      | m         | Root zone thickness (sum of depths is total depth of root penetration)  |
| root_fract      | fraction  | Fraction of root in the current root zone.                              |

OPTIONAL - If BLOWING_SNOW is TRUE in global parameter file, then for each vegetation tile, the following parameters must appear after the list of root depth/fract parameters:

| Variable Name   | Units   | Description                                                                           |
|---------------  |-------  |-------------------------------------------------------------------------------------  |
| sigma_slope     | N/A     | Standard deviation of terrain slopes within vegetation tile                           |
| lag_one         | N/A     | Lag-one autocorrelation of terrain slope within vegetation tile                       |
| fetch           | m       | Average fetch (distance the wind blows without obstructions) within vegetation tile   |

OPTIONAL - If VEGPARAM_LAI is TRUE in global parameter file, then for each vegetation tile, there must be a line containing the following parameters:

| Variable Name   | Units     | Description                     |
|---------------  |---------- |-------------------------------- |
| LAI             | fraction  | Leaf Area Index, one per month  |

OPTIONAL - If VEGPARAM_FCAN is TRUE in global parameter file, then for each vegetation tile, there must be a line containing the following parameters:

| Variable Name   | Units     | Description                                       |
|---------------  |---------- |-------------------------------------------------- |
| FCANOPY         | fraction  | Partial vegetation cover fraction, one per month  |

OPTIONAL - If VEGPARAM_ALBEDO is TRUE in global parameter file, then for each vegetation tile, there must be a line containing the following parameters:

| Variable Name | Units    | Description           |
|---------------|----------|-----------------------|
| ALBEDO        | fraction | Albedo, one per month |

## Example Vegetation Parameter File:

    ###  Two vegetation tiles with three root zones in the seventh grid cell
    ###  with LAI included.
    7 2
        8 0.102679 0.10 0.10 1.00 0.65 0.50 0.25
          0.312 0.413 0.413 0.413 0.413 0.488 0.975 1.150 0.625 0.312 0.312 0.312
       10 0.897321 0.10 0.10 1.00 0.70 0.50 0.20
          0.212 0.262 0.275 0.338 0.750 1.275 0.950 0.650 0.450 0.288 0.237 0.212
