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Flood risk assessments in the Norwegian flood research program


									                                                 Nils Roar Sælthun

Flood risk assessments in the Norwegian
    flood research program HYDRA

               Nils   Roar Sælthun, NIVA
                  Hallvard Berg, NVE
            Hans Olav Eggestad, Jordforsk
           Lars Gottschalk, University of Oslo
                   Irina Krasovskaia
          Morten Skoglund, The SINTEF Group
                   Astrid Voksø, NVE
           Magne Wathne, The SINTEF Group
                                            Nils Roar Sælthun

The HYDRA Programme
   HYDRA is a research programme on flood initiated
    by the Norwegian Water Resources and Energy
    Administration (NVE) at the beginning of 1995. The
    major flood in south-eastern Norway in the spring
    of 1995 made the programme particularly relevant.
                                             Nils Roar Sælthun

Working Hypothesis
   The working hypothesis is that the sum of all
    human impacts in the form of land use, regulation,
    flood-protection etc., may have increased the risk
    of floods.
                                            Nils Roar Sælthun

   HYDRA is aimed at developing knowledge,
    information and methodology to support state and
    municipal authorities, insurance companies and
    other organisations in their work and decision
                                                       Nils Roar Sælthun

Time frame, funding and participants
   Time frame of 3 years, terminating in 1999
   Economic framework of NOK 18 million
   Funding: The Ministry of Petroleum and Energy.
   Executing parties:
        Norwegian research institutions and universities
        Norwegian Water Resources and Energy Directorate,
        one river authority.
   Board of users
                                                    Nils Roar Sælthun

   Impacts of watershed land use.
   Flood impacts in urban areas.
   Flood reduction, flood protection and flood management.
   Risk analysis.
   Environmental consequences of floods and flood prevention
   Integrated watershed/watercourse/floodplain modelling
   Databases and Geographical Information Systems (support
    activity at NVE).
                                                  Nils Roar Sælthun

Risk analysis project
   The main objective: to improve the methodology for
    loss assessments - aimed at streamlining
    cost/benefit analysis of flood mitigation measures.
   Central components
        R1: Damage/loss functions
        R2: Improving flood mapping
        R3: Flood analysis and risk analysis
        R4: Improved front line decision tools
                                              Nils Roar Sælthun

R1: Damage/loss functions
   Objective: Establish standardised loss functions for
    various objects with special emphasis on buildings
    and cultivated land, based on assessments and
    inventories after the 1995 flood
                                                 Nils Roar Sælthun

R1: Objects investigated
   Buildings
   Infrastructure
        roads (direct and indirect costs)
        railroads (direct and indirect costs)
        flood levees and erosion protection
   Agricultural areas
        physical damage
        crop losses
                                                                                         Nils Roar Sælthun

Damage to buildings


 Damage (kNOK)

                                                                                      Constr. yr 1850-1942

                 600                                                                  Constr.yr 1946-94

                                                                                      Trend line 1850-1942

                 400                                                                  Trend line 1946-94


                        0   100        200        300        400          500   600
                                  Water level (cm) (ground level = 200)
                                       Nils Roar Sælthun

R2: Improving flood inundation
   Objectives:
        Improving flood zoning
        testing of various base
         map types and laser
        identification of exposed
         objects and areas by use
         of GIS and digital property
                                            Nils Roar Sælthun

R3: Flood analysis and risk analysis
   Improved regional flood frequency analysis
   Flood line estimation
   Test and verification of loss curves
   Establish frequency/damage curves
                                                            Nils Roar Sælthun
Regional flood   Normalised regional frequency curve for Glomma (PDS)
                 observed floods 1966 (blue),1967(green),1995(red)(SPDS)
frequency                  6



                            0.1            1           10                   100
                                               scale parameter

                                   -    Ret ur n       -        pe ri o d      -
                                  10      50          100         500        1000

                                                                Upstream Upstream
                               Glomma   Laagen     Downstream
                                                                Glomma Laagen
                                              Nils Roar Sælthun

R4: Improved front line decision
   Public perception of risks
   Public reactions to abandoning and evacuation
   Local decisions under lack of external information
   Decision trees
   Methods:
        polls
        expert panels
        fuzzy set analysis

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