Floods
  High water is a natural phenomenon leading to rivers overflowing and to extensive flooding as a result of persistent rainfall and snow melting. Since the natural floodplains are populated and subject to intensive economic exploitation, flood damage is sustained which involves material loss as well as a risk to human life.
Flood control primarily takes the form of technical measures such as building barrages, water retention basins, dams and dikes. Ecological measures aim at natural retention of water by the protection and renaturation of floodplains and retention areas.
Forecasts and simulations identifying flood risk areas for certain water level values (e.g. hundred year flood) are necessary for deciding on the necessity and scope of flood control measures.

High-precision digital terrain models, as are produced with the TopoSys laserscanner, are vital as the basis for hydraulic determinations of flood risk areas and risk analyses. TopoSys supplies high-resolution basic data for manifold applications and preventive measures for the flood prevention and water resources management sector:
 

Color-coded DSM Lahn
© BfG, Germany
  • Calculation of hydraulic simulations (1D and 2D)
  • Determining flood areas
  • Producing flood risk maps and risk analyses
  • Producing basic planning principles for disaster control
  • Recording drainage channels
  • Measuring water levels
 

Relief image DSM Frankfurt/Oder
© DLR, DFD-AN, Germany
  Profiles and cross sections used in hydraulic simulations can be extracted at any location from the area-wide elevation models.

Cross section Wolterdingen
© Gewässerdirektion Riedlingen, Germany
  A problem posed in the further processing of TopoSys data for applications relating to water resources management is the extremely high data volume of the raster elevation models. High accuracies and high data densities are vital in changing topography, but often redundant in flat, planar areas. By expedient data thinning in the form of a Triangular Irregular Network (TIN), the data volume is reduced many times over without losing the essential information relevant to water resources management.

An overview of the subject is given in the Flood Protection and Hydraulic Simulations application flyer for download.

Danube flood risk analysis project
 

Danube forecasts
© Wald + Corbe, Germany

 In the Danube flood risk analysis, TopoSys DSM and DTM elevation models served as a main processing basis for producing the hydraulic simulation model, for determining the flood areas and for forecasting diverse scenarios.


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