Assessment of damage caused by high groundwater inundation

In several cities around the world, problems with rising groundwater levels were reported, but up to now, losses caused by high groundwater levels have been neglected in loss assessment studies. However reliable loss assessments are necessary to evaluate the cost‐effectiveness of mitigating measures like groundwater withdrawal and drainage. To improve the knowledge about flood losses and the loss‐influencing factors, 1697 households affected by the Elbe and Danube floods in 2002 in Germany were interviewed. Cases affected by a high groundwater level were identified and analyzed in comparison with cases affected by riverine flooding. Inundations due to high groundwater show significantly different impact and damage characteristics in comparison with riverine floods. Most common loss models tested were as such not suitable to estimate losses due to high groundwater. Therefore, new loss models have to be developed. One step in this direction is the development of loss models just on basis of loss data from groundwater flooding. From all such models tested, the multifactorial model FLEMOps+ performed best, confirming that the uncertainty in loss estimation can be reduced if more predictive variables, besides the water level, are taken into consideration. However further research is necessary to investigate the main factors influencing the losses due to groundwater flooding and to develop specific models for their assessment.