Hydrological modelling
Hydrological modelling traces how water moves over and under the ground: where it runs, where it collects, and which areas drain to which streams. In GIS it starts from a terrain model and is sensitive to everything that model gets wrong, from filled hollows to bridges that look like dams.
Hydrologically corrected terrain models
The problem of bridges Bridges and hydrological modelling (Example)
Typical questions
- Where does surface water run, and where does it collect?
- Which areas drain to a given stream or lake?
- Where is the risk of flooding?
Often used data
Through the SPHERE leaves: Elevation, Surface flow systems, Catchments, Freshwater bodies, Flood hazard.