«Regional forecasting service for rainfall-induced landslides in Norway» Graziella Devoli NVE/UiO

Transcription

1 «Regional forecasting service for rainfall-induced landslides in Norway» Graziella Devoli NVE/UiO Section for Forecast flood and landslide hazards Hydrology Department, NVE October 2017

2 Example of EWS for Norway Norway: Nordic country, high-income country Climate: Artic and Continental climate Geology: Caledonian metamorphic rocks and quaternary fluvial and glacier sediments Type of landslides: debris flows, debris avalanches, debris slides, small and shallow soil slides along roads, railways, slush flows (also rock slides that can generate tsunamis, sensitive clay slides and rock falls) Main triggering of landslides: Rainfall (Large scale, low pressure systems, extra tropical cyclones; local summer convective rainfall) Snowmelt Type of landslide material: moraine deposits, fluvial, colluvial deposits 2

3 Rests of Hurricanes Maria and Nate, (Kristin), 14 sept Norway Many debris slides and debris flows in Western Norway. This landslide at Hatlestad, Bergen, killed 3 people, 14 september 2005

4 Forecasting services at NVE Flood forecasting Landslide & debris flows Snow avalanche Monitoring and warning of large unstable rock slopes (..tsunamis or valley blockage) Flood: 1989 Snow avalanche: January 2013 Debris flows/debris slides: October 2013 Unstable rock slopes: January

5 Water stream flow, 10 June 2011 Photo NVE Debris flow Eikesdalen, july 2014 Photo S. Tjelle Type of landslides: Shallow soil slides, debris slides/avalanche and debris flows, slush flows (runout 3-5 km; velocity 5m/s) Triggered by rain, rapid snowmelt or a combination Yearly severe economical losses along roads and railway Slush flow, Dovrefjell, Mai.2010 Snøhetta Foto: Adressa.no 5

6 Snowmelt induced spring flood Gudbrandsdalen, East Norway, summer 2011 Foto Scanpix 6

7 Heavy rain induced flood Flåm Foto vg.no Odda, West Coast. October 2014 Foto NRK.no 7

8 Summer showers induced Flash flood/debris Flows Notodden, South Norway - 23 juli 2011 Foto J. Simonsen 8

9 Growing problem? Compensations paid Events in 2013: Debris flows Soil slides Clay Debris (unspec.) Snow avalanches Millions NOK 9

10 Warning portal: varsom.no 10

11 Use of landslide warning Click in the Warning-area Test message and susceptibility map (brown area) 11

12 Examples of Warnings, May th 16 th -19 th 20 th 21 st 22 nd 23 rd 24th -30 th 12

13 Landslide awareness levels Be prepared! < 50 year flood Extreme situation! General safe conditions! About 300 days/year Generally safe conditions Man-made landslide Be aware! < 5 year flood About days Situation that requires monitoring Expected some landslide events, certain large events may occur. Local flooding and/or erosional damage 4-8 days Sever situation Expected many landslide events, some with considerable consequences. Extensive flooding, erosional damage and flood damage 0-2 days Extreme situation Expected many landslide events, several with considerable consequences. Extensive flooding, erosional damage and flood damage to buildings and infrastructure. Number of days in period

14 Hazard assessment: steps 1. identify and notify local emergency authorities and the public about potentially dangerous hydrological situations (for 3 days ahead); 2. information about an ongoing situation and expected development so that the situation can be handled best possible locally. 14

15 Daily Weather forecast (Temperature and precipitation) is received from meteorological institute and used as input in hydrological models Nedbør Nedbør Temperatur Weather forecast interpolated 1x1 km 2 grid in xgeo.no 15

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17 From the HBV model several simulated parameter are obtained every day 17

18 Besides simulated parameters we use real-time observations 18

19 Landslide data From xgeo.no 19

20 Who/where landslide data are registered? Regobs.no Road maintainance - El Rapp! Personnel on duty Road authority intern controll Other institutions, Private consultants Landslide database NSDB: skredregistrering.no Skrednett.no Limitations: double registrations 20

21 Landslide thresholds Water supply Based on empirical data over 209 landslide events, but regional corrections are in progress Soil water content 21

22 Representation of the thresholds (Hydmet), xgeo.no 20 th May (morning) 21 st May (morning) 22 nd May (morning) 22 nd Landslide hazard assessment is based on the thresholds, other simulated hydrological parameters, real time observations, susceptibility maps and expert-knowledge 22

23 Work in progress to increase precision in warnings: Forecasted hydro-meteorological index (soil saturation and rain & snowmelt) combined with a susceptibility maps at catchment level (geology, geomorphology, slope, yearly rainfall, various runoff variables) Hydmet: Thresholds (only hydrometeorological conditions) Landslide susceptibility map at catchment level Hydmet GEO: Thresholds corrected with landslide susceptibility 23

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25 Landslides, Eastern Norway May 2013 Bilde Issued warning message Observed landslides Photo: RØ, NVE 25

26 New thresholds for south-eastern Norway Weekly rainfall from 15th to 22nd may 2013 Observed landslides the 22 th May 2013 Foto NTB scanpix 26

27 Operational since 2013, after a period of test ( ) Flood/snow avalanche and landslide forecasting services Synergy effects: Weather forecasts, hydrological models, observations. Development of common decision tools warning portals, organisation/personal 27

28 Tools & apps to monitor/record events, evaluate and communicate natural hazards Elrapp Road operation data base for contractors & road authority regobs.no Observations registered by professionals and public (Crowdsourcing) Retriever: Media monitoring xgeo.no : Expert tool to evaluate flood, landslide and avalanche hazards Senorge.no: Public version varsom.no Warning portal on flood, landslide and avalanche hazards on regional scale 28

29 Organization 8:00-21:00 nationwide forecasting and warning service About 12 forecasters from NVE and 2 from NPRA (Roads Administration) Multidisciplinary teams: Hydrologists, hydrogeologists, geologists 1 forecaster on duty for one week (+ 1 second call in working time Daily briefing at 9:00 with a meteorologist from MET Norway 29

30 Management and economy $ Estimated costs for landslide service (in 2016): 14,7 mill. NOK (1.8 mill US$, but 1.2 millus$ are in common with snow avalanche forecasting service) Includes forecasters compensation, research & development, management, etc. 30

31 Few warnings and flood events in 2015 and

32 Evaluation of the system HEC method 1 Between yellow/orange or orange/red level 32

33 International workshop October 2016 reliable landslide data, thresholds, validation of warning, communication 50 participants From Europe: BGS, INERIS, CNR, ARPA PIEMONTE, IMO, SGI, WLS, Wildbach Norway:NVE, MET, SVV, Bane NOR, NGU, NGI, UiO USA: USGS 34

34 More information about the workshop: /nyheter-flom-ogjordskred/better-landslidewarning-to-be-betterprepared/ 35

35 References (Norway) Piciullo L., Dahl M-P., Devoli G., Colleuille H., Calvello M. (2017). Adapting the EDuMaP method to test the perforamnce of the Norwegian early warning system for weather-induced landslides. Nat. Hazards Earth Syst. Sci., 17, Devoli G., Jorandli L., Engeland K., Tallaksen L.M. (2017), "Large-scale synoptic weather types and precipitation responsible for landslides in southern Norway". Proceedings of World Landslide Forum 4, 29 May-2 June 2017, Ljubljana Devoli G. (2017) Workshop «regional early warning systems for rainfall- and snowmelt-induced landslides. Need for an international forum?» NVE rapport nr. 4/2017. Norges vassdrags- og energidirektorat, Oslo, Norge. Bell R., Cepeda J., Devoli G. (2014). Landslide susceptibility modeling at catchment level for improvement of the landslide early warning system in Norway. Proceedings 3rd World Landslide Forum 3, 2-6 June 2014, Beijing. Boje S, Colleuille H, Cepeda J, Devoli G (2014). Landslide thresholds at regional scale for the early warning system in Norway. Proceedings 3rd World Landslide Forum 3, 2-6 June 2014, Beijing. Devoli G., Kleivane I., Sund M., Orthe N-K., Ekker R., Johnsen E., Colleuille H. (2014). Landslide early warning system and web tools for real-time scenarios and for distribution of warning messages in Norway. Proceeding IAEG 2014, September, Torino, Italy 36