watem Tool Library¶
Tool Library
| Name | Watem |
| Author | Johan Van de Wauw 2016 - 2017 - gebaseerd op originele pascal code van KULeuven.Ontwikkeld in opdracht van Vlaamse overheid, departement Omgeving. |
| ID | watem |
| File | /__w/saga-watem/saga-watem/build/libs/saga/libwatem.so |
Description
SAGA Implementatie van het WaTEM model (KULeuven).WaTEM is a spatially distributed soil erosion model that was developed at the Physicaland Regional Geography Research Group (K.U.Leuven, Belgium).The development of the SAGA-WaTEM module was financed by Vlaamse overheid (Vlaams Planbureau voor de Omgeving, Departement Omgeving).
Tools
[1] Calculate uparea¶
Tool
| Name | Calculate uparea |
| Author | Copyright (c) 2006 - 2016 by KULeuven. Converted to SAGA/C++ by Johan Van de Wauw |
| Version | 2023.10.23 |
| Library | watem |
| ID | 1 |
| Specification | grid |
Description
This module converts a digital elevation model grid and a parcel grid and converts it to an upslope area. The method takes into account parcel borders, water (grid value -1) and landuse (forest has value 10000). The upstream area is computed from higher to lower pixels, within the boundaries of a parcel. At parcel/forest-, parcel/parcel-, parcel/infr-boundaries, the upstream area is reduced with the connectivity (1-x) parameters. Pits are taken into account, such that flow is transported over maximum number of pixels (PIT_RADIUS) (otherwise ignored). Optionally a grid with Pits and a table with pit information can be generated. No river routing is considered, such that the upland routing 'ends' at the river boundary.Parameters
| Name | Type | Identifier | Description | Constraints |
|---|---|---|---|---|
| Input | ||||
| Digital elevation model | Grid, input | DEM | ||
| Parcel grid | Grid, input | PRC | Parcel grid with: - a unique identifier per parcel: [2,9999] - Forest = 10000 - Infrastructure & roads = -2 - Water (river/open water) -1 | |
| Output | ||||
| Pit | Grid, output | PIT | Pit id. These id's are linked to the id's in pit data. | |
| Upslope Area | Grid, output | UPSLOPE_AREA | Upslope Area: area that flow to a certain pixel | |
| Pit data | Table, output, optional | PITDATA | Table per found pit. Coordinate according to the grid in watem. | |
| Options | ||||
| Parcel Connectivity to cropland (%) | Floating point | PCTOCROP | Percentage of water that will be reduced from a cropland (parcel) to another cropland (parcel). | Minimum: 0.000000 Default: 70.000000 |
| Parcel Connectivity to forest (%) | Floating point | PCTOFOREST | Percentage of water that will be reduced from a cropland (parcel) to forest. | Minimum: 0.000000 Default: 100.000000 |
| Parcel Connectivity to infrastructure/roads (%) | Floating point | PCTOROAD | Percentage of water that will be reduced from a cropland (parcel) to infrastructure/roads | Minimum: 0.000000 Default: 70.000000 |
| Flow from pits into closeby cells (within radius) (True/False) | Boolean | PIT_FLOW | If pits occur (local minima in the digital elevation model) water can flow to nearby cells if they are lower and within the PIT_SEARCH radius if this option is enabled. | Default: 0 |
| Search radius from pit. | Integer | PIT_RADIUS | Maximum search radius for flow from pits. | Default: 4 |
[2] LS calculation¶
Tool
| Name | LS calculation |
| Author | Copyright (c) 2003 Olaf Conrad. Modified by Johan Van de Wauw (2016) to make model identical to WaTEM |
| Version | 2023.10.23 |
| Library | watem |
| ID | 2 |
| Specification | grid |
Description
This module computes the LS-factor given a digital elevation model, parcel grid and upslope area (see calculate uparea. The slope at boundaries is calculated perpendicular to parcel boundaries. Different methods can be used to compute the LS (see 'Method to compute LS').Parameters
| Name | Type | Identifier | Description | Constraints |
|---|---|---|---|---|
| Input | ||||
| Digital elevation model | Grid, input | DEM | Digital elevation model (m) | |
| Upslope Area | Grid, input | UPSLOPE_AREA | Upslope Area: area that flow to a certain pixel. Can be created using the 'Calculate uparea' tool (watem-1). | |
| Parcel grid | Grid, input, optional | PRC | Parcel grid with: - a unique identifier per parcel: [2,9999] - Forest = 10000 - Infrastructure & roads = -2 - Water (river/open water) -1 | |
| Output | ||||
| Calculated LS | Grid, output | LS | Calculated LS factor | |
| Slope | Grid, output, optional | SLOPE | Optional Slope output grid | |
| Calculated L | Grid, output, optional | L | This will contain L. | |
| Calculated S | Grid, output, optional | S | This will contain S. | |
| Options | ||||
| Use parcel borders in slope calculation. | Boolean | USEPRC | If enabled, only pixels inside the same parcels will be used for slope calculation, to avoid highincorrect slopes due to border effects such as sunken roads and embankments. | Default: 1 |
| Method to compute LS | Choice | METHOD | There are four options available: - Moore & Nieber (1989): see model description-page. - Desmet & Govers (1996): see model description-page. Using McCool et al. (1989, 1987) for the parameter m. - Van Oost (2003): same as Desmet & Govers, but with a different computation model for the parameter m. - Wishmeier a Smith (1978): see model description-page. - . | Available Choices: [0] Moore & Nieber 1989 [1] Desmet & Govers 1996 (default of WaTEM) [2] Wischmeier & Smith 1978 [3] Van Oost, 2003 Default: 1 |
[3] Watererosion based on LS (RUSLE)¶
Tool
| Name | Watererosion based on LS (RUSLE) |
| Author | 2016-2017 - Johan Van de Wauw |
| Version | 2023.10.23 |
| Library | watem |
| ID | 3 |
| Specification | grid |
Description
Determine watererosion based on LS(grid)-, K(grid)-, C(grid)-, R(value)- and P(value)-factor. A correction for accounting differences in resolution can be used (see 'Resolution correction factor'). In addition the RUSLE values can be limited to a maximum value (see 'Flag maximum gross erosion'). A NULL value in K, C or LS return a NULL valueParameters
| Name | Type | Identifier | Description | Constraints |
|---|---|---|---|---|
| Input | ||||
| LS | Grid, input | LS | LS: topographic slope and length factor (dimensionless), can be created using the 'LS calculations' tool (watem-2). | |
| K-factor grid | Grid, input | K | soil erodibility factor (K-factor, kg ha MJ-1 mm-1) | |
| C-factor Grid | Grid, input | C | Grid containing the crop and management factor. Should be defined as a grid with values between 0 and 1. | |
| Output | ||||
| Water erosion | Grid, output | WATER_EROSION | Average soil loss due to rill and interrill erosion (kg ha-1 year-1) | |
| Options | ||||
| R-factor value | Floating point | R | rainfall erosivity factor (MJ mm ha-1 year-1) | Minimum: 0.000000 Default: 880.000000 |
| P-factor value | Floating point | P | erosion control factor (dimensionless, between 0 and 1) | Minimum: 0.000000 Default: 1.000000 |
| Resolution correction factor | Floating point | CORR | Correction factor for resolution as RUSLE was determined on resolution of 22.1 meter. This value is set to 1.4 for grids of 5x5 (see Notebaert et al. 2006) | Minimum: 0.000000 Default: 1.400000 |
| Flag maximum gross erosion | Boolean | EROSION_CROP_MAX | Use maximum allowed erosion per pixel (True/false) | Default: 1 |
| Maximum allowed gross erosion. | Floating point | EROSION_MAX | Maximum allowed erosion per pixel, higher values are set to the specific defined value (default 150). | Minimum: 0.000000 Default: 150.000000 |
[4] Tillage erosion calculation¶
Tool
| Name | Tillage erosion calculation |
| Author | Copyright (c) 2006 - 2016 by KU Leuven. Converted to SAGA/C++ by Johan Van de Wauw |
| Version | 2023.10.23 |
| Library | watem |
| ID | 4 |
| Specification | grid |
Description
Calculation of Tillage Erosion based on DTM (grid) and parcels (grid). Based on the code from WaTEM (KU Leuven). Tillage erosion, or soil translocation by tillage, is calculated according to the method of Van Oost et al. (2000). See model description for more information on the formula's. Note that the tillage transport coefficient is hardcoded being 600 kg/m.Parameters
| Name | Type | Identifier | Description | Constraints |
|---|---|---|---|---|
| Input | ||||
| Digital elevation model | Grid, input | DEM | Digital Elevation Model (m). | |
| Parcel grid | Grid, input | PRC | Parcel grid with: - a unique identifier per parcel: [2,9999] - Forest = 10000 - Infrastructure & roads = -2 - Water (rivers and open water) = -1 | |
| Output | ||||
| Tillage erosion | Grid, output | TILL | Average soil loss due to tillage erosion (kg ha-1 year-1) | |