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GIS Toolbox for risk evaluation

GIS for floods

The EU Flood Directive (Directive 2007/60/EC) was proposed by the European Commission on 18/01/2006, and was finally published in the Official Journal on 6 November 2007. Its aim is to reduce and manage the risks that floods pose to human health, the environment, cultural heritage and economic activity.

At River Basin scale, River Authorities are responsible for computing flood events of a designed return period and provide related maps.

Maps of flooded areas are the main tool to immediately identify and evaluate the risk.

Climate Change seems to have shorten the return period of extreme rainfall events. Furthermore any changes on environment use (land use or soil type) impact on the catchment response of such events.

Here a procedure to create maps of floods for selected areas is presented.

The role of GIS

Hydrological and hydraulic modelling for the calculation of water depth, in selected areas of the catchments and for a defined return period, require a lot of geographic information. GIS are the most powerful tool to handle and to present these data.

  1. Watershed and stream Network delineation. GRASS and QGIS

  2. Characteristics of the sub-basins. GRASS+QGIS

  3. Reach slope, Time of Concentration and Lag Time calculation

  4. Creation of SCS Curve Number and Impervious area layer via GIS

  5. Weighted rainfall layer

The GIS added value in the water management process

Flood events can impact also on water resources asset. For instance it is possible to see if a certain wells field is affected by the flooding water, and give suggestion on how to plan the water supply in case of such event. 


IN GENOAGIS_floods_Genua.html
IN EINDHOVENGIS_floods_Eindhoven.html