flood hazard mapping - nveflood hazard mapping rengifo ortega section for geoinformatics norwegian...

Flood hazard mappingRengifo Ortega

Section for geoinformatics

Norwegian Water Resources and Energy Directorate

People need space, so do rivers

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… so do people

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Historical overview

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Flood marks 1675- 1995

1789 largestflood in Norway

1995 Secondlargestflood, Glomma River

1997 National MappingProgram

Since then,125 rivers have been mapped, covering about 1250 km river length


Overall responsibility

■ Prevention ofdamages causedby flood

■ Assist local authorities to■ Identify hazard■ Analyse and evaluate the risk

associated with that hazard and■ Determine appropiate ways to eliminate or control the hazard

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Mapping Plan

■ Areas with the largestpotential risk

■ -> existing houses and infrastructures

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Flood mapping methods –steps

Flood estimation

Hydraulicmodelling

1D/2D

GIS Analysis

Flood hazardmap

Digital production

and reporting


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Hydraulic modelling

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• Site visits• Cross sections

Field work

• Watermarks• Boundary conditions

Calibration • 1D modelling, Hec-Ras +mike11

• 2D modelling Mike 21 +Hydro AS 2D

• Calibration

Hydraulicmodelling


Hydraulic modelling

■ Site visit/cross sections■ Alb (green Laser)■ Urban area■ Water marks (calibr)■ Boundary conditions■ Modelling ->

HEC-RAS + Mike11Mike21 + Hydro AS (2D)

■ Calibration10


Hydraulic simulations

■ Discharges from flood estimation■ Model

■ Results in water levels

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0 500 1000 1500 2000 2500350

355

360

365

370

375

380

162.

79

233.

1315

P3

267.

2207

P4

305.

119

P5.

5 B

RU

386.

4169

P7

425.

735

P7.

5 O

bser

vert

2011

445.

3940

P8

482.

5500

P9

536.

4312

P10

581.

5272

P11

608.

1265

633.

2941

670.

6488

696.

0299

P19

715.

8412

P20

770.

6352

P22

819.

1430

P23

887.

8465

P24

1018

.018

P26

1066

.067

P27

1104

.452

P28

1266

.185

P29

1306

.608

P30

1332

.158

P31

1372

.221

P32

1470

.868

P33

1801

.223

P34

1978

.511

P35

2191

.564

P36

2298

.549

P37

2451

.013

P38

2562

.780

P39

2690

.873

P40

2915

.937

P41

Green = Q500Red = Q200Blue = Q20


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GIS Analyse 1DDigital terrain model Flooded areas


GIS analyse 2D

14DTMIrregular mesh

Thiessenpolygons


What new in GIS analyse 2D

■ Change detectionbased on digital elevation modell ofdifferences (DoD)

■ Sediment mapping■ Differentiate

Manning’s coefficient■ Habitat modelling

15Hydrographic LiDAR


What new in GIS analyse 2D

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Flooded Area

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Resultat frå flaumanalysen i Årdal 200-årsflaum med klima


Knowledge - tools

■ Land Use Planning-> Avoid development in flood

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■ Emergency-> Mitigate impacts

Civil protection

■ Protection plan-> Flood embankment

Measures in buildings

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Experiences• Local involvement is important• Most of the communities are willing to use the results• Guidance and control from the government is

necessary


Employees

■ Section for Hazard Mapping – 2■ Regional Office in Tønsberg – 2■ Regional Office in Førde – 1■ Regional Office in Trondheim – 2■ Regional Office in Hamar – 1■ Section for Water Balance – 2■ Section for Geoinformation – 3

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Flood maps in PDF formathttp://www.nve.no/flomsonekart

WebGIShttp://atlas.nve.no/ge/Viewer.aspx?Site=NVEAtlas

1D vs 2D- Pros and Conshttp://www.tuflow.com/Download/Presentations/Syme.Pros%20and%20Cons%20of%201D%20and%202

D%20Modelling.FMA,%20San%20Diego,%202011.pdf

Thanks for your attention!

flood hazard mapping - nveflood hazard mapping rengifo ortega section for geoinformatics norwegian...

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