WEPPcloud Documentation

WEPPcloud Documentation

WEPPcloud Calibration

Disturbed Land Soil Lookup Table (PowerUser Panel → Modify Disturbed Parameters)

The disturbed land soil table in WEPPcloud contains parameters that define soil properties for various land use categories and soil textures. These parameters are essential for modeling erosion and hydrology in disturbed lands using the WEPP (Water Erosion Prediction Project) model. The table includes data for combinations of land use (e.g., agriculture crops, forest, bare) and soil texture (clay loam, loam, sand loam, silt loam).

Table of Parameters

Parameter Description Units
luse Land use category (disturbed class from the land use map) -
stext Soil texture (clay loam, loam, sand loam, silt loam) -
ki Interrill erodibility kg·s/m⁴
kr Rill erodibility s/m
shcrit Critical shear stress (τc) N/m² or Pa
avke Effective hydraulic conductivity mm/h
ksflag Flag to use internal hydraulic conductivity adjustments (0: no, 1: yes) {0,1}
ksatadj Adjustment factor for saturated hydraulic conductivity -
ksatfac ignore - will be removed -
ksatrec ignore - will be removed -
pmet_kcb Basal crop coefficient (Kcb) -
pmet_rawp Parameter for readily available water -
rdmax Maximum root depth m
xmxlai Maximum leaf area index frac
keffflag Flag for lower limit of effective conductivity (lkeff; 0: no, 1: yes) {0,1}
lkeff Lower limit of effective conductivity (-9999 indicates no adjustment) mm/h

Additional Notes and Other Parameters of Interest

Effective Hydraulic Conductivity (avke)

Determined from field data. Do not change unless you have a good reason.

Interrill Erodibility (ki)

Interrill areas are the sheet flow zones between small channels (rills) on a hillslope. Interrill erodibility measures the soil’s susceptibility to detachment by raindrop impact and shallow sheet flow. It is influenced by:

Units: kg·s/m⁴
Note: Do not change.

Rill Erodibility (kr)

Rills are small channels formed by concentrated flow on hillslopes. Rill erodibility is the soil’s susceptibility to detachment by concentrated flow (not raindrop impact). Rill erosion is generally more intense on steeper and/or longer slopes and can cause greater sediment transport than interrill erosion.

Units: s/m
Note: Do not change.

Critical Shear Stress (τc)

This is the minimum hydraulic shear stress required to initiate detachment of soil particles in rills. Below this threshold, the flow is not energetic enough to detach soil. It acts as a resistance parameter in rill erosion models.

Units: N/m² or Pa
Note: Do not change.

Basal Crop Coefficient (pmet_kcb)

The Kcb parameter for the FAO Penman-Monteith equation approximates net evapotranspiration from meteorological data as a replacement for direct measurement of evapotranspiration.

Units: None
Guidelines:

For more information, see: Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56, Chapter 7 - ETc - Dual crop coefficient (Kc = Kcb + Ke)

Rain-Snow Temperature Threshold

Found under WEPP Advanced Options - Snow.

Units: °C
Range: -3 to 1

Underlying Bedrock Conductivity (ksat for restrictive layer - kslast)

Found under WEPP Advanced Options - Bedrock

Units: mm/h
Default: Based on SSURGO values (ksat of the last horizon / 100, or other rules).
Range: 0.001–0.1

Baseflow Coefficient

Found under WEPP Advanced Options - Baseflow Processing.

Units: per day
Range: 0.01–0.04

Channel Critical Shear Stress (τc)

Found under WEPP Advanced Options - Channel Parameters

Units: N/m² or Pa Range: 0.05 (fine silt) and 170 coarse cobble Guidelines: