Environmental Engineering Reference
Extensive information of both databases can be found on the website http://eusoils.
jrc.it/ESDB_Archive/ESDBv2/fr_intro.htm . A number of soil variables that are
important from an agronomic perspective were selected to define the most
important ones in explaining the variation in soil properties (see Methods ).
Description of TOPsoil Organic Carbon (OCTOP)
OCTOP is published by Jones et al. (2004 , 2005b). This topsoil (0-30 cm)
organic carbon dataset is the result of a novel approach combining a rule-based
system (provided by pedo-transfer rules) with detailed thematic spatial data layers.
The effects of land use, vegetation and temperature were taken into account in
the calculations to estimate the organic carbon contents. Point data extrapolation
was not suitable to generate the database as the number of samples for Europe is
insufficient, data were insufficiently geo-referenced and the organic carbon
contents vary within soil units depending on vegetation and land management
(Jones et al. 2005 b). The resolution of the dataset is a one by one km grid spacing.
This resolution is regarded as appropriate for planning effective soil protection
measures at European level. The estimation or determination of the spatial distribution
of organic carbon content of soils will have always an element of uncertainty.
The data sources used to compile the OCTOP database are:
European Soil Database version 1.0 (ESDBv1) (Heineke et al.
European Land Cover Data (combination of CORINE Land Cover [CLC]) of the
EEA and Eurasian land cover (United States Geological Survey [USGS])
Average Annual Accumulated Temperature (AAAT) from the Global Historical
Climatology Network (GHCN) (Easterling et al. 1996).
Description of the Global Digital Elevation Model (GTOPO30)
GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing
of 30 arc seconds (~1 km). The global dataset is covering the full extent of latitude
from 90° south to 90° north, and the full extent of longitude from 180° west to 180°
east. The horizontal coordinate system is decimal degrees of latitude and longitude
referenced to the coordinate system WGS84. The vertical units represent elevation
in meters above mean sea level. The elevation values range from −407 to 8,752 m.
In the digital elevation model, ocean areas have been masked as “no data” and have
been assigned a value of −9,999. For more information on the dataset we refer to