iMPACT-Start
The iMPACT-Start is a set of Notebooks explaining and implementing the starting soil erosion modelling tasks:
This is the list of the iMPACT-start Notebooks and links to run them online.
1. Fill climate data gaps using probability distributions: Teaches how to fix missing weather records (like rainfall or temperature) using statistics. If a weather station has gaps in its data, this Notebook shows how to estimate those missing days/months by analyzing patterns from existing data.
Click here to run the Notebook online
2. Fill sinks of the digital elevation model (DEM): Fixes “holes” in digital elevation maps that disrupt water flow simulations. These holes (sinks) might be real (like volcanic craters) or errors in the map.
Click here to run the Notebook online
3. Flow accumulation of the surface water flow: Flow accumulation is a critical step in hydrological modeling and analysis. It indicates how water flows across the terrain, accumulating from higher elevations down to lower elevations. This Notebook includes:
- Determination of slope gradients and flow directions
- Shows how water moves downhill across a landscape using two methods:
- D8: Simple “water flows to one neighboring cell”
- Dinf: Realistic “water splits between multiple cells”
Click here to run the Notebook online
4. Catchment delineation: Helps users define the area that drains to a specific point, i.e. a catchment or watershed. You pick a point and the Notebook automatically draws the surrounding hills/mountains that feed water to it. This Notebook includes: - Definition of the catchment outlet and boundaries. - Determination of flow direction and flow accumulation maps and flow routing of the delineated catchment.
Click here to run the Notebook online
5. Rainfall erosivity (R-factor): Measures how much heavy rain contributes to soil loss. Uses rainfall data to calculate the “R-factor” – a number representing rain’s ability to erode the soil.
Click here to run the Notebook online
6. Soil erodibility (K-factor): Determines how easily soil washes away based on:
- Texture (% sand/silt/clay)
- Organic matter
- Permeability
Uses USDA’s Nomograph method.
Click here to run the Notebook online
7. Topographic factor (LS-factor): Calculates how terrain steepness and upslope length increase erosion. Uses elevation maps to identify areas where water gains speed and volume as it flows and concentrates downhill.
Click here to run the Notebook online
8. Land cover management factors (C & P factors): Quantifies how land use affects erosion:
- C-factor: Vegetation cover (forests protect soil better than bare fields)
- P-factor: Farming practices (contour plowing reduces erosion vs. up/downhill rows)
Click here to run the Notebook online
This website is under development and we will be gradually adding new Notebooks.
If you find errors/bugs or you would like to contribute, please contact us.