SAGA GIS WaTEM module (SAGA-WaTEM)

This repository contains a SAGA-GIS translation of the WaTEM erosion model. WaTEM (Van Oost et al. 2000) is a spatially distributed model that computes erosion by rainfall and tillage:

• Water erosion: soil erosion occurring by natural rainfall water.

• Tillage erosion: soil erosion occurring in cultivated fields due to the movement of soil by tillage.

The main usage of this package is to compute WaTEM. The module is split in two submodules, one to compute WaTEM, and another submodule with specific tooling for an application for Flanders.

The installation guidelines can be found here, whereas the description of the model is presented here. An example is presented to help users get started with the module. In addition, explanation is given about the extra tooling available for the application for Flanders.

Currently, the module contains one extra module, see Topology.

Legacy

The SAGA-WaTEM module is a derivative product of the code that was devoloped for the ‘erosiekaart’ for Flanders (see below). The tool was developed in 2016 (in Dutch), and was fully documented and refactored in 2024 by Fluves.

Consequently, the current tooling is structured in a different way compared to the initial tool. As of now, it consists of two modules (watem and watem-flanders) to make a clear distinction between tools relevant for computing the gross erosion (core) and tools relevant for preprocessing data from Flanders as input for the core tool.

The tool is now structured as follows:

• watem:

  1. Calculate uparea (used to be module 3.1)

  2. LS-calculations (used to be module 3.2)

  3. Watererosion based on LS (RUSLE) (used to be module 3.4)

  4. Tillage erosion calculations (used to be module 3.5)

• watem-flanders:

  1. Prepare parcel map (used to be module 1)

  2. 3x3 filter within parcel boundaries (used to be module 2)

  3. C calculation based on parcel grid (used to be module 3.3)

  4. C calculations shape attribute (module 3.6)

  5. Compute Calculations Erosion map (combines all steps) (used to be 2.5)

References

Van Oost, K., 2003. Spatial modeling of soil redistribution processes in agricultural landscapes. (PhD thesis). KU Leuven, Leuven.

Contents

User guide

• Introduction
• Model description
  • Water erosion
  • Tillage erosion
  • Subfactors
    • R-factor
    • K-factor
    • LS-factor
    • C-factor
    • P-factor
  • Implementation
  • References
• Installation
  • Installing SAGA
    • On windows
    • On linux
  • Building saga
    • On windows
    • On debian/ubuntu linux:
    • Running automated tests
    • Command line interface
• Getting started
  • The WaTEM module
  • Compute water erosion
  • Compute tillage erosion
• Flanders application
  • Parcels map generation
  • Filtering digital elevation model
  • C-grid
  • Complete tool
• Topology
  • Topology
  • Upstream edges
  • Shreve order and Sort order
  • Special cases
    • Split paths
    • Circular routes

Module Reference

• WaTEM
  • [1] Calculate uparea
  • [2] LS calculation
  • [3] Watererosion based on LS (RUSLE)
  • [4] Tillage erosion calculation
• WaTEM Flanders
  • [1] Prepare parcel Map
  • [2] 3x3 filter within parcel boundaries
  • [3] C calculation based on parcel grid
  • [4] C calculation shape attribute
  • [5] Complete Calculation Erosion map (combines all steps). See submodules for more information.
• Topology
  • [0] Topologize Polylines
  • [1] Upstream Edges
  • [2] Routing to shape
  • [3] Segment to subcatchments
• Line direction
  • [0] Line Direction

Developer Guide

• Authors
• Changelog
• License

Indices and tables

• Index

• Module Index

• Search Page