Coastal Flood Hazard and Risk Maps in Denmark Thorsten Piontkowitz & Laura Storm Henriksen, Danish Coastal Authority
Contents Introduction Denmark and the coastal zone Identified flood prone areas Flood Hazard and Risk Mapping The HARIMA-approach Hazard analysis Vulnerability analysis Results Outlook Conclusions Future challenges SIDE 2
Denmark and the Coastal Zone Seaside town Inland town Copenhagen SIDE 3
Identified Flood Prone Areas Flood prone area Randers Fjord Flood prone area Køge Bay SIDE 4
The SPR-model Source Pathway Receptor Surge Coastal flood defence Flood prone area
The HARIMA Approach 1 GIS - database Hazard analysis 2 3 Hydraulic boundary conditions Reliability analysis 4 Inundation modelling Vulnerability analysis 5 6 Tangible losses Intangible losses Risk assessment 7 Flood risk assessment SIDE 6
Hazard analysis (Hydraulic boundary conditions) Extreme value statistics Scenarios Scenarios Low probability (extreme event scenarios) Medium probability 1/100 High probability 1/20 Open coast [Hw] Extreme events used in accordance with Article 4(2)(b,c) Overtopping approach Climate scenario 2050, medium probability Climate scenario 2050, high probability Climate scenario 2100, high probability 1/100 + 30 cm SLR ± local land movement 1/20 + 30 cm SLR ± local land movement 1/100 + 80 cm SLR ± local land movement Land movement SIDE 7
Hazard analysis (Numerical modelling) Standardised storm surge curves MIKE 21 FM: Model setup 21. februar 2002 06. januar 2012 20. december 2001 6. december 2003 2. januar 2002 VS 100 år VS 20 år 12:00 21-02-2002 00:00 21-02-2002 12:00 22-02-2002 00:00 22-02-2002 12:00 Roughness map 21. februar 2002 20. december 2001 2. januar 2002 12:00 21-02-2002 00:00 21-02-2002 12:00 22-02-2002 00:00 22-02-2002 12:00 SIDE 8
Vulnerability Analysis Material damages and losses Casualties, cultural assets Interruption of trade and transport Loss of confidence, increase of survivors sensitivity Depth-damage functions Buildings Inventory Agricultural acreage Livestock Infrastructure Cultural losses Shown on the maps Number of inhabitants Hazard companies Installations Protected nature SIDE 9
Cell-Based-Risk Assessment Grid sizes: 25 x 25 m 50 x 50 m 100 x 100 m 200 x 200 m 500 x 500 m All maps are available at WebGIS. Ref. Burzel & Oumeraci, 2012
Three map groups Hazard and flood damage maps (flood extend, total economic damage) Solrød Strand, 100-year event (2012) Solrød Strand, 1000-year event (2012) SIDE 11
FHRM public available http://miljoegis.mim.dk/spatialmap?&profile=oversvoem2 SIDE 12
Contents Outlook Conclusions Future challenges SIDE 13
Conclusions The 7-step method, including the applied tools, allowed to prepare flood hazard maps and flood risk maps for all 10 flood prone areas having a significant diversity in spatial extent, flood exposure, vulnerability, with the limited data and time available. The selected 7-step method has been a very useful, since the assessment of the flood risk approached in a structured and comprehensible way that allows to be communicated to others (e.g. end-users). The process and results showed, that the following topics need to be addressed further in future: - flooding hazards issues (extremes, data, sources, climate projections) - incorporation of other risk sources - numerical modelling vice versa GIS-tools, since modelling is very time-consuming - further development of damage functions - the transfer of risk analysis results to risk communication and decision making SIDE 14
Changes/adaptations in 2 nd cycle Consideration of multi-hazard scenarios in fjord areas. Consideration of a more detailed reliability assessment of flood defences (GISbased) Evaluation and further adaptation of depth-damage functions and the furhter consideration of tangible and intangible losses SIDE 15
Thank you for your attention! Højbovej 1 DK-7620 Lemvig Denmark Tlf: 99 63 63 63 E-mail: kdi@kyst.dk www.kyst.dk