Operational methodology to assess flood damages in Europe

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Alexander Solomon Fowler
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1 IIASA-DPRI 2008 Operational methodology to assess flood damages in Europe Contributors: Nicola Lugeri, Carlo Lavalle, Elisabetta Genovese 1

2 Focus of ADAM work on extremes Types Floods, Heat-wave, Drought and frost to agriculture, Forest fire, Windstorms to forests. Public and private sector Key vulnerable areas according to Adaptation Green paper: Southern Europe and the entire Mediterranean Basin exposed to a combined effect of high temperature increases and reduced precipitation in areas already stressed by water scarcity. Densely populated floodplains, exhibiting an increased risk of storms, intense rainfall and flash floods leading to severe and widespread damages to built-up areas and infrastructure. 2

to a combined effect of high temperature increases and reduced precipitation in areas already stressed by water scarcity.

3 Brief WP history Definitions and Methodologies agreement needed because of: Different scientific/humanistic backgrounds Different fields of application Different targets Different geographical/political scales Fundamental methodology was chosen; technical implementation adapted to the different hazards/fields 3

Different targets Different geographical/political scales Fundamental

4 Risk definition Flood risk = hazard x exposure x vulnerability Hazard is the threatening natural event including its probability/magnitude of occurrence; Exposure is represented by the values/humans that are present at the location concerned by the hazard. This is typically expressed by statistics on population, socio-economic data on sectorial activities and infrastructure; Vulnerability (a) measures the extent to which the subject matter could be affected by the hazard. (b) It is the lack (or loose) of resistance to damaging/destructive forces. It is therefore the indication of the measures taken (or to be taken) to mitigate the effects of extreme events. Risk is a potential loss having uncertain occurrence and size. It is a consequence of hazard, vulnerability and exposure. 4

This is typically expressed by statistics on population, socio-economic data on sectorial activities and infrastructure; Vulnerability (a) measures the extent to which the subject matter could be

5 Risk triangle Exposure Intensity vs. damage Intensity and frequency 5

6 Scale (FLOOD site guidelines on an integrated European methodology for flood risk analysis and management) 6

7 Exposure LAND COVER / LAND USE Average Land prices Demography Crop yield statistics Vulnerability Damage Fraction vs. flood depth Harvest Index vs. phenology Hazard Flood Hazard Map Water depth Flood extent area Return period Heat/water Stress Map Temperature/duration Precipitation lack/duration Return period METHODS: GIS overlay Regression analysis Crop simulation DAMAGE GIS Analysis by Spatial units [Grid / NUTS 3] 7

phenology Hazard Flood Hazard Map Water depth Flood extent area Return period Heat/water Stress Map

8 1KM GRID FLOOD HAZARD MAP It is obtained using a 1 km grid digital elevation model and the 1 km European flow network developed by the WDNH. An algorithm has been developed to find the elevation difference between a specific grid-cell and its closest neighbouring grid-cell containing a river, while respecting the catchment treestructure. This map is therefore based on purely topographical information, although linked to a river network. No hydrology is included Elevation difference Flood Hazard Class Pixels representing a river (buffer of 1km) 0m 6 (HIGH HAZ.) 5 (HIGH HAZ.) m 4 (HIGH HAZ.) m 3 (LOW HAZ.) m 2 (LOW HAZ.) > 6.0 m NO HAZ. Coastal areas 7 Lakes 1 8

the catchment treestructure. This map is therefore based on purely topographical information, although linked to a river network.

9 Risk assessment: operational approach at EU scale Socio-economic indicators at different administrative levels Flood Hazard Map Weight factors on land values Weight factors on vulnerability Vulnerability (flood depth) Hazard CLC 2000 CLC 1990 Exposure of assets (with temporal dynamics) 9

factors on land values Weight factors on vulnerability Vulnerability

10 Macro scale 1 Analysis through indicators Results produced often on administrative units (NUTS) Partial Analysis, H*E, thus considering VULNERABILITY=1 (neutral) HAZARD by the Flood Hazard map (1km) EXPOSURE: - Territorial assets - Population 10

thus considering VULNERABILITY=1 (neutral) HAZARD by the

11 ANALYSIS BY ADMINISTRATIVE UNITS AND BY CLC LEVELS NUTS0 CLC LEV.1 NUTS2 DB CLC LEV.2 NUTS3 CLC LEV.3 Year 2000 Year

Damage Assessment in a large River Basin The Mekong Experience. Phan Nguyen& Anthony Green Mekong River Commission

Damage Assessment in a large River Basin The Mekong Experience Phan Nguyen& Anthony Green Mekong River Commission Contents 1. Features and vulnerabilities 2. Influence of Changing Climate 3. Damage Assessment