Floods constitute a major natural hazard, resulting in large global losses every year. This relates to both the direct damage caused by flooding (i.e. to buildings, crops) as well as the economic-wide impact that can go beyond the flooded area itself, and have effects until long after the flood itself. Various measures can be taken to mitigate or reduce losses. However, in order to prioritize measures and evaluate their cost-effectiveness, it is necessary to have a good grasp on the consequences of flooding, even though this longer-term and often indirect damage is hard to capture and assess.
On the one hand, with climatic change affecting the global, regional and local water systems (i.e. in the form of sea-level rise), the risk of flooding and flood hazards is increasing. On the other hand, global population continues to grow, and with increased urbanisation, modern cities are becoming more and more dense in terms of people and valuable assets. They can be characterised as high-risk damage intensive areas, where a high level of connectivity can lead to spatial and temporal chain reactions.
In order to support decision making in flood risk management, it is necessary to have reliable estimates of the potential consequences. Integrated modelling of direct damage and indirect losses, linked to specific flood events (i.e. 1/100 year flood) is necessary for this. Recent coupling of damage models with economic models makes it possible to estimate a priori such consequences and evaluate different measures, supporting decision making in regard to what to do, where to implement activities, and when to become active. This methodology requires:
1) The collection of relevant data related to the hydrological system and/or flood events;
2) The collection of relevant information on exposure (i.e. land-use assets);
3) The collection of economic data (e.g. input-output tables);
4) The integration of this data in a risk assessment model with modules for direct and indirect damages; and finally
5) The adjustment of the model in order to evaluate impacts of future scenarios (socio-economic, climate) and/or policy options (flood proofing, reservoirs, etc).
FACILITATORY (PUBLIC) BODIES:
land use planning department; planning and development department; water and sewerage management department; environmental and sustainability department; socio-economic development department
LOCAL TASK FORCE:
local or regional authority; professional expert
dense inner city; urban region; (sub-)urban communities
MAIN NECESSARY RESOURCES ARE:
monetary investments; expert knowledge; public institutional set-up; local knowledge
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