Arup led a consortium to define the flood risk zones of Poland’s River San and its 53 tributaries in preparation for implementation of the EU Flood Directive. Delimitating flood zones for various flood events is the first step of work required by the Directive leading to proper management of the flood risk.
This £0.6m project covered 29,000km2 and involved modelling rivers which required us to survey 3,500 channel cross-sections so that river channels are measured every 500 meters and all structures (weirs, foot bridges, bridges, water intakes, pipes crossing the channels) are clearly identifiedand as well as surveying 126km of flood defences.
Fluvial and GIS modelling
We conducted fluvial modelling using industry-standard Mike 11 software for all 54 rivers, based on hydrological calculations for catchments controlled and uncontrolled by water gauge stations. We also carried out geographic information systems (GIS) modelling to establish flood zones for seven hypothetical floods of given probabilities.
The scope of our technical services included catchment inventory, hydrology, data gathering, site surveys, identifying flood zones, using GIS to prepare maps, and writing the final report.
Training sessions were run for local councils, showing the benefits of using digital flood maps in day-to-day work.