Physical Properties – Soil Types

In this section we describe the topsoil maps and parameters used by various parts of the Scalgo Live system. For instance, some, or all, of these are used in the Flash Flood Map with infiltration and drainage and in Core+ DynamicFlood. We refer to the documentation of those analyses for more information about how the soil parameters are used.  

In Scalgo Live we use two sets of topsoil types, both reflect the composition of the soil in terms of dominant grain sizes:

1. A set of topsoil types based on the soil texture triangle defined by the USDA. This topsoil typology covers all soil types in the world. 

2. A set of topsoil types based on the Danish classification system known as JB (jordbundstyper). This topsoil typology is specifically designed for the types of soils typically found in Scandinavia. 

In order to create a map of topsoils for each country, we use the most relevant soil map we can find for the country and the most suitable of the typologies above. Futhermore, we use our land cover map, and other information, to modify the soil map to better represent the top layer of soil in high resolution. This process is described in more detail in the mapping section. Finally, we assign Horton parameters and porosity to each of the topsoil types in various degrees of compaction as described in the properties section. 

Topsoil types based on the USDA soil texture triangle

The USDA soil texture triangle defines 12 major soil texture classes based on the fraction of sand, silt and clay particles in the soil (after other particles such as organic materials and large stones have been removed). This classification is broadly accepted and widely used across the world. 

In order to create a typology that covers all possible cases of dominant texture in the topsoil, we add the classes "Rocks and boulders", "Gravel", "Gyttja/peat", "Bedrock", "Glacier" and "Water" to the original USDA classes. Obviously, water and glacier are not soil types, but the type of soil found under a glacier or a water body is mostly unknown, and we need to decide what happens with water that enters a cell with these land cover types, hence we include them in the typology.  

Table: Overview of our USDA-based classes along with their integer IDs. The IDs are used when downloading the soil layers from Scalgo Live.

Topsoil types based on the Danish JB soil classification

The Danish JB classification system includes 11 classes of soil ranging from coarse sand to very fine clay, silt and gyttja/peat. The classification of a given soil is done based on the fractions of sand, silt and clay (after other particles such as organic materials and large stones have been removed), as with the USDA triangle, but also takes into account how much of the sand fraction is fine sand. 

Note that the naming of the classes is completely independent between these two classification systems, such that a soil that is classified as "Clay" in the JB system may be a "Sandy loam" according to the USDA system.  

In order to create a typology that covers all possible cases we add the classes "Rocks and boulders", "Gravel", "Bedrock", "Glacier" and "Water" to the original JB-classes. Obviously, water and glacier are not soil types, but the type of soil found under a glacier or a water body is mostly unknown, and we need to decide what happens with water that enters a cell with these land cover types, hence we include them in the typology. 

Table: Overview of JB-classes along with their integer IDs. The IDs are used when  downloading the soil layers from Scalgo Live.