IIHR Seminar (December ) KYUTAE LEE

1. The need for assessing Flood Risk? 2. Risk analysis/assessment – general overview 3. Issues in current practice of Flood Risk Management 4. Role of uncertainties in flood risk management 5. Example: Multicriteria Risk Mapping Approach (MCA)

Providing information for rational decision making to People I nformation on individual flood risk raising awareness & preparedness Insurance industry calculation of probable maximum loss (PML) calculation of insurance rates Government investments in flood protection: - Financial needs for protection measures - Evaluation and selection flood protection measures

Past / today: Safety-Standard Approach Mainly structural measures (e.g., levees, dikes) Provides same safety level for all inundated area (neglecting the different damage potential, hence inefficient allocation of resources) Emerging: Risk management Approach Consideration of the whole spectrum of risk reduction measures Efficient allocation of funds based on a cost-benefit analysis (by using multi criteria, estimating the damage function) Approaches

(Modified from Schanze (2006))

(Plate (2002))

Damage evaluation – necessary information (Adapted from Meyer, 2007)) 1. Risk Analysis 2. Hazard Determination 3. Inundation maps by hydrological and hydraulic model 1.Risk Assessment 2.Vulnerability Determination 3.Flood Damage model Flood Risk maps

1. Uncertainty estimation Flood risk assessment is always to some degree uncertain, but these uncertainties in the results should be documented in order to provide decision makers with information on the quality of the data they are using as a decision support. 2. Evaluation of the Social & Environmental Risks - Social & Environmental Risks are often neglected since they are not (easily) measurable in monetary terms. - Focusing on only economic damages makes often the results of Flood Risk Assessment incomplete, biased. 3. Spatial distribution of Risks The spatial distribution of risks is rarely considered. E.g. One area might be more vulnerable than other areas for 100 yr flood.

Uncertainties in Risk Management Upper bounds representing Maximum expected AAD Lower bounds representing Minimum expected AAD

Incorporates all relevant types of risks (Social, Economic & Environmental) without measuring them on a monetary scale. 1. Economic  Annual Average Damage 2. Environmental  Erosion potential (of material)  Accumulation potential (of material)  Inundation of oligotrophic biotopes 3. Social  Annual average affected population  Probability of social hot spots (hospitals, schools etc.) of being affected