The HydroSHEDS database provides global hydrographic
data for hydrological applications. The second, refined
version of the database is improved by using the highresolution TanDEM-X digital elevation model (DEM). In order
to derive hydrologic data from the terrain, during the socalled pre-conditioning, the DEM is edited and ancillary
layers are calculated. Prior steps of the editing include,
among others like void and outlier correction and the
derivation of a coastline and water body mask, an urban
correction.
When river networks are derived from a DEM, visible
artificial structures can divert the streams as they intercept
the natural course of the riverbed. Therefore, during the last
step of the pre-conditioning, the urban correction aims to
reduce such diversions caused by built-up structures
