Master Thesis Opportunity

The inclusion of flood defences in flood hazard maps

Flood hazard maps give insight in the area that is potentially prone to flooding for events with different return periods and / or flood levels. Flood maps are made a global scale, at national/regional level (e.g. as part of the requirements of the European flood  directive) and at local/urban scale. In the current practice, national/regional level but also global flood maps are generally made without considering the effect of flood defences. However, this leads to an overestimation of hazard zones, exposure and risk levels and a bias in risk communication. In this study it will be investigated how the effects of flood defences can be incorporated in flood hazard mapping, particularly for areas for which there is limited information on the exact conditions of flood defences.

A study considering of four parts is proposed:

1. Review of existing methods for flood mapping and assessment of flood defences:
   
   • Flood mapping with and without flood defences (binary approach);
   • Simplified methods to assess performance and reliability analysis such as expert judgement and standardized fragility curves;
   • Full reliability analysis
     Based on this information, a method will be proposed on how to include (and “weigh”) information on the probability of flood defences failures into flood hazard mapping.
2. Assessment of effect of breaching and overtopping of flood defences on flood patterns (e.g. limitation of inflow etc. particularly in coastal areas with storm surge and tidal effects) by studying simplified cases and thereafter real-life case studies. The intent of the simplified cases is to better understand better in what situations the inclusion of levee failure is important (or not) for flood hazard mapping (expressed in terms of flood extent, depth, etc.).
   
   
3. An investigation in how flood maps can be (visually) presented for areas including the effects  of flood defences, also targeting on various user groups and decision making. Case studies: Europe: Romania (or Serbia) for a riverine system.
   
   
4. Optional: Review of data sources to include flood defences in flood hazard maps: including existing databases which include information on flood defences (FLOPROS, JRC for Europe) will be performed, as well of global data sources (DEMs) and technological capabilities (e.g. from satellites)

Supervision: Bas Jonkman, dr. Mathijs van Ledden (World Bank), more information: s.n.jonkman@tudelft.nl