Soil and topography
Soil characteristics and topography are determining factors for many ecosystem services. Land use changes and soil hydrology (GHG and GLG) have important implications for various ecosystem services such as infiltration, water retention, carbon sequestration in soil, ...
The Belgian soil map was created based on the results of intensive soil mapping during the 1950s to the 1970s. This Belgian soil map is based on the Belgian soil classification system. It is a national system that was drawn up exclusively for Belgian soils. A number of map layers from this soil map are used here. The map can also be found at: https://www.dov.vlaanderen.be/page/grondkaart
Soil texture​
The soil texture map is based on the digital soil map of Flanders (AGIV 2006). The soil map does not cover the whole area because, among other things, built-up areas have not been mapped. The coastal region also had a different coding. VITO has attempted to make the map complete (Joris et al. 2017). On this map you can read what type of soil the soil consists of. The following types are distinguished within the Nature Value Explorer:
U - heavy clay (>50% clay)
E - clay (at least 30% clay)
A - loam (85% loam)
L - sandloam (60% loam)
P - (light) sandloam (35% loam)
S - loamsand (20% loam)
Z - sand
X - dunes
G - stony loam
V - peat
W - raised peat
OB - built-up zone
OT - quarry
OE - raised area
ON - excavated area
other = other codes that appear on the soil map and are usually combinations of the above.
Soil moisture​
This map shows the moisture of the soil (the extent to which the soil drains). The drainage condition of a soil depends on the depth of the groundwater, the permeability of the superficial layer, the occurrence at varying depths of a poorly permeable subsoil, the depth of the soil and the topographical conditions.
The following classes are used:
a - excessively drained soils (very dry)
b - well drained soils (dry)
c - moderately drained soils (moderate dry)
d - imperfectly drained soils (moderate wet)
e - poorly drained soils (wet)
f - very poorly drained soils (very wet)
g - extremely poorly drained soils (extremely wet)
h - poorly drained soils with perched or seasonal groundwater (wet)
i - very poorly drained soils with perched or seasonal groundwater (very wet)
A - soil moisture a + b + c + d
B - soil moisture a + b
D - soil moisture c + d
E - soil moisture d + e
F - soil moisture e + f
G - soil moisture e + f + g + h + i
H - soil moisture g + h
I - soil moisture h + i
Soil profile​
Under the influence of climatic and biological factors, the parent material undergoes weathering and other soil formation processes, which are manifested in the formation of more or less clear soil horizons. A distinction is made between organic horizons (O) and mineral horizons (A-B-C). The organic horizons, which only occur under natural vegetation (forest, swamp), consist of fresh or partially decomposed plant remains that accumulate on the surface. The A horizon includes the dark-colored, humous surface horizon; the thickness can vary from a few centimeters to several decimeters. The B horizon, often 40 to 60 cm thick, consists of clearly differentiated material. The C horizon includes the undifferentiated parent material
The following groups are distinguished in the Nature Value Explorer:
a - soils with texture B horizon
b - soils with colour B or structure B horizon
c - soils with strongly mottled or broken texture B horizon
d - soils with yellow-red texture B horizon
e - soils with a thick dark A horizon
f - soils with a poorly expressed iron, or humus B horizon
g - soils with a well developed iron, or humus B horizon
h - soils with a broken iron, or humus B horizon
m - soils with a thick anthropic humus A horizon
p - soils without any profile development often of alluvium or colluvium
x - not determined
B - soil structure a + b
C - soil structure c + f
F - soil structure b to f
G - soil structure b + g + h
P - soil structure p + x
Soil according to the World Reference Base (WRB) for soil resources​
The WRB maps are a translation of the soil map according to the Belgian soil classification system into an international reference code. In the calculation of the carbon storage service in the soil, this classification is used to determine the carbon stock.
The occurrence of the following classes has an influence on carbon in the soil:
Anthrosol: Soils with strong human influence and with long-term and intensive agricultural use
Arenosol: Relatively young sandy soils or sandy soils with little or no profile development
Gleysol: Soils affected by groundwater
Histosol: Soils with thick organic layers
Podzol: Soils established by Fe/Al chemistry with cheluviation and chilluviation. (1) Cheluviation: leaching of soluble metal-humus complexes (chelates) from the surface layers to deeper layers in the soil profile. (2) Chilluviation: subsequent accumulation of Al and Fe chelates in a spodic B horizon.
Retisol: mixing of material with a coarser structure and a lighter color with a layer with a finer structure and a stronger color
Presence of peat​
Peat is a type of soil that is made up of humified plant material. This wet, spongy soil type is formed by dead plants in wetlands and later preserved under wet, low-oxygen conditions. The map indicates the places where peat soil is still present in Flanders (only V and W in the soil map). The presence of peat soil influences the carbon stock in a soil.
Average highest groundwater level GHG (cm)​
This map, created by UAntwerp in the context of ECOPLAN, provides a reference image for the average highest groundwater level for Flanders (the shallowest groundwater level). GHG is the average of the 25% highest groundwater levels of the year in the area. It is based on an interpolation of the drainage classes of the digital soil map for Flanders, where topographical corrections have been made based on the DHM for Flanders (AGIV 2014). How this happened can be found in the manual of the ECOPLAN-SE plug-in (Vrebos et al. 2017), which can be found in the background documents of the Nature Value Explorer.
Average lowest groundwater level GLG (cm)​
This mapr, created by UAntwerp in the context of ECOPLAN, shows the potential natural average lowest groundwater level (the deepest groundwater level). GLG is the average of the 25% lowest groundwater levels of the year in the area. This map layer is an interpolation of the drainage classes of the digital soil map for Flanders (AGIV 2006), where topographical corrections have been made based on the DHM for Flanders (AGIV 2014).
Slope percentage (%)​
The slope is a measure of the steepness of an inclined plane. The slope is expressed in percentages (%). This is why it is also referred to as the slope percentage (S). This map shows the places in Flanders where there is a certain slope. This input is used in the "soil carbon storage" service.
LS factor​
The LS factor is a measure of the impact of slope (steepness) and runoff from upstream (slope length). The LS factor was calculated within ECOPLAN according to the formulas of Desmet and Govers (1996) and McCool, Brown et al. (1987) and was made available in a finished map layer. This map is used for the "avoided erosion" service.
K-factor​
The K factor indicates the erosion sensitivity of the soil. The map we use here is a map generated from the Flemish model for calculating the potential erosion map (Notebaert et al. 2006). This map is used for the "erosion avoidance" service
R factor​
The rain erositivity factor (MJ mm/ha.h.y) was calculated for the refined potential erosion map for Flanders (Notebaert et al.). This factor was later updated by Gobeyn et al. 2021.
It was decided to use an average value of 1250 MJ mm/ha.h.y for the whole of Flanders. The Nature Value Explorer takes over this value.
This map is used for the "erosion avoidance" service.