Infiltration Data in Flood Simulationv:
Infiltration is a crucial process in flood simulation, as it determines how much water filters into the soil instead of becoming surface runoff. In the tool, infiltration data is essential for calculating how water is distributed and accumulated in the terrain. The system uses soil property data provided by SoilGrids to estimate infiltration rates in different regions of the world.
SoilGrids: Infiltration Data
SoilGrids is a global soil property dataset provided by ISRIC – World Soil Information. This dataset uses machine learning methods to map the distribution of soil properties worldwide, based on approximately 230,000 soil profile observations from the World Soil Information Service.
Main Features of SoilGrids:
- Global soil properties: The dataset provides global soil properties at six standard depth intervals ranging from 0 cm to 200 cm deep.
- Spatial resolution of 250 meters: This means each data point represents an area of 250 square meters, offering a detailed view of soil properties on a global scale.
Calculation of Infiltration Rates
To calculate infiltration rates, the system uses the global prediction of soil texture and organic matter provided by SoilGrids, combined with the pedotransfer functions from Saxton et al. (2006). These functions estimate soil infiltration rates based on soil properties such as texture type and the amount of organic matter present.
- Soil texture: Soil texture (e.g., sand, silt, clay) directly influences infiltration speed, as sandy soils allow for greater infiltration compared to clayey soils.
- Organic matter: Soils with higher organic content generally have higher water retention capacity, and therefore, can have higher infiltration rates.
Resampling to Improve Digital Elevation Model (DEM) Resolution
The estimated infiltration rates are adjusted to higher resolutions to match the resolution of the Digital Elevation Model (DEM) used in the system. This rescaling of infiltration rates is crucial for improving flood modeling accuracy, as it ensures that the soil model resolution matches the elevation model resolution used to simulate water flow.
The system provides infiltration rate maps that can be downloaded from the website. These maps visualize how infiltration varies across different areas, allowing users to analyze the water absorption capacity in different regions.