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JUNE 2017
SCREENING OF VULNERABILITY TO CLOUDBURST FLOODINGELEVATION MODELS
Linda Bredahl, Senior Consultant, M.Sc.
JUNE 2017
causes heavier rain events in Denmark and problems with subsequent drainage of the terrain in urban areas.
To assess how vulnerable an area is to flooding we analyse the hydrological conditions of the terrain - using Model Builder.
The weather
becomes more extreme:
•Higher rain intensities
•Higher wind speeds
•Longer droughts
Various methods are used depending on the project area, its characteristics and purpose for each project - all involving Spatial Analyst and 3D Analyst.
Terrain regulation is done, using ArcGIS tools, to create urban areas and climate resilient cities
CLIMATE CHANGE..
JUNE 2017
MY PROFILE
Linda BredahlSenior ConsultantM.Sc.
Area: Rambøll Water
Department:Urban Water Management, Climate Adaptation andGreen Infrastructure
Danish Height Model (DTM/DSM) - high resolution - nationalFirst step: screening of the terrainGIS analysis – Spatial Analyst, hydrological tools, & 3D AnalystUrban flooding – calculationsRemote sensing
JUNE 2017
BACKGROUND EXAMPLE
July 2011: The capital of Denmark was hit by the worst and most destructive cloudburst in the city’s history
Damages caused by floods:6 billion DKK or approx. 1,07 billion USD
150 millimeters of rain in 2 hours
BACKGROUND EXAMPLE
JUNE 2017
INITIATED PROJECT WITH TASKS• Initial analysis of:
Traffic TerrainUrban character and spacesExisting structuresDamage reports
• Hydraulic modelling
• Socioeconomics
• Masterplans
• Design
• Costs and benefits
5
JUNE 2017
STANDARD LOW POINT SCREENING
Screening of surface (not detailed calculation with sewer pipe system)
JUNE 2017
MODEL FOR STANDARD SCREENING
Standard: fill up to 25 cm! If the terrain is very flat this gives some very big basins.
Con…
The basins of a certain size, most commonly 1 ha - depends on the characteristics of the terrain
JUNE 2017
BASIS FOR FIRST DECISION MAKING
JUNE 2017
BASIS FOR FIRST DECISION MAKING
JUNE 2017
MASTER PLANNING
JUNE 2017
• Depression analysis (as we just saw)
• Blue spot analysis
• Simple blut spot
• Advanced blue spot
LEVELS OF SCREENING
Small depressions
Catchment area
TWI (Topografic wetness index)
Permeability
Rain event
JUNE 2017
Blue: > 100 m3
Red: < 100 m3
Blue: > 25 cm
Red: < 25 cm
JUNE 2017
MORE BLUESPOTS..
Blå: > 100 m3
Rød: < 100 m3
JUNE 2017
Volumen > 100 m3
Upstream area > 1 ha
JUNE 2017
THE POUR POINT CHALLENGE
JUNE 2017
JUNE 2017
THANK YOU
ANY QUESTIONS?
