BopaBW – Near-surface soil parameter Baden-Wuerttemberg

Country / Region: Germany/Baden-Württemberg

Begin of project: January 1, 2018

End of project: May 31, 2023

Status of project: December 31, 2022

Fig. 1. Arable land in Baden-Wuerttemberg as base data to define the areas for deriving near-surface soil parameters Source: BGR, Data source: ALKIS (Amtliches Liegenschaftskatasterinformationssystem), digital elevation model DEM10 Baden-Wuerttemberg

The digital soil map of Baden-Wuerttemberg with a scale of 1:50000 (BK50) is based on traditional soil surveying methods like soil sampling, laboratory analysis, and forestry and vegetation survey. Additionally, various maps (geological and topographic maps) and relief parameters, derived from digital elevation models, are used for generating the BK50. However, so far no remote sensing datasets were included in that soil map owing to the high fees for commercial satellite products, low spatial and/or spectral resolutions and the fact of only detecting the surface of the soil. Since 2015, the Sentinel-2A and 2B satellites are continuously generating multispectral satellite scenes within the Copernicus Mission that are free of charge. The satellites orbit the complete earth every 5 days/10 days and record it with a spectral resolution of 13 bands, differently in spatial resolution (10 m/20 m/60 m).

The objective of the joint project „Near-surface soil parameters Baden-Wuerttemberg“, with lead of the State Authority for Geology, Mineral Resources, and Mining (LGRB) in cooperation with the BGR and the German Research Centre for Geosciences (GFZ) Helmholtz Center is to derive near-surface soil parameters of arable land from satellite data (Fig. 1). These near-surface soil parameters might serve as additional soil information in combination with the existing BK50.

Such near-surface soil parameters are e.g. soil texture or the degree of surface stone cover. The estimation and quantification of chemical soil parameters like contents of organic carbon and carbonates are likewise important as physical soil parameters to be implemented in EU-, state and federal regulations.

Collected hyperspectral laboratory (Fig. 2) and field measurements (Fig. 3) are calibrated and validated with Ground-Truth data. The LGRB owns an extensive soil database with field survey data, analytical data, and carbon modelings to be used for that purpose. That database is continuously updated and complemented with hyperspectral field data. Additionally, soil information like mineralogical parameters and element contents are generated in laboratory analysis by BGR.

Beyond that, the hyperspectral field and laboratory measurements are combined with multispectral signatures of Sentinel-2 scenes to derive the near-surface soil parameters directly from the satellite data (Fig. 4).

Complementary, Sentinel-1 radar data is used to test its efficiency for monitoring the degradation of peatlands in Baden-Wuerttemberg. Disturbed water balance of peatlands causes mineralization of peat and leads to a continuous degradation and subsidence of peatlands.

By that process, organic carbon is primarly emitted as climate-relevant emission to the atmosphere. Regarding the changes in elevation of peatlands in combination with peat parameters might enable the estimation of CO2-emissions. Sentinel-1 data, based on radar interferometry, provide subsidence and uplift rates (Ground Motion Service Germany (BBD)) and allow to depict the current elevation change of peatlands on a high resolution.

Partner:

State Authority for Geology, Mineral Resources, and Mining (LGRB)
German Research Centre for Geosciences (GFZ) Helmholtz Center