River Ice and Flooding Simulation :
Communication of Geospatial Expertise

Situation:

In late January and early February 2004, a variety of conditions –cold temperatures over an extended period, heavy snowfall, greater than normal reservoir discharges – combined to create problems with ice dams, frazil ice build-up, and localized flooding along the Rivière des Praires in Québec. The river is a major tributary of the St. Lawrence, and runs through an urbanized zone at the boundary between the cities of Montréal and Laval. The flooding was considered a significant danger for those cities. L’organisation de Sécurité civil du Québec (SCQ) monitored the situation closely and coordinated public safety measures and efforts to reduce flooding.

The “script” that follows is a simulation, based on a scenario of use developed by the SCQ’s parent, the DOTSC (part of the Québec Ministry of Public Security [MSP]). The visualizations in the screen shots are use real data from February 2004.

In the simulation an SCQ emergency management counsellor at the Montreal regional operations centre (COR) opens up the meeting, based on a GeoConference session, to:

►      Assess the current ice/flooding situation with colleagues and external experts (present at their various places of work or assignment);

►      Introduce a synoptic view of the ice and frazil situation based on Radar satellite imagery products produced by the Institut national de recherché scientifique – Eau, terre, environnement (INRS-ETE) in Québec City.

►      Agree on actions to be taken.

 

The GeoConference session include the following participants:

►      COR: the regional counsellor chairing the meeting from the Regional Operations Centre of the Direction régionale de Montréal, Laval, Lanaudière et des Laurentides (DRMLLL, part of DOTSC), Montréal.

►      DRMLLL-Laval: Counsellor from the DRMLLL, in place in the city of Laval (accompanied by local officials).

►      DRMLLL-Montréal: Counsellor from the DRMLLL, in Montréal.

►       DGSCSI: Scientific counsel from the parent organization of the DOTSC, in Québec City.

►      INRS-ETE: Radar earth observation specialist from INRS-ETE in Québec City.

Before the part of the session shown here, the counsellors from the DRMLLL have located a number of annotations on the map showing problem areas.

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1 COR -- Hello everyone. Our objective here is to review the current situation and decide on any actions to be taken.

We’ll start with an overview of the western part of the Rivièere des Prairies. You can see some of the area that are already either flooded or in danger of flooding due to ice jams.  Now we’ll zoom in on the western-most problem areas in Ste-Dorothée-Roxboro area.

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2. COR – I’m adding some layers from the CIT WMS to make it a little bit easier to get located.

 

COR – As you can see, there are areas subject to flooding on both sides of the river. On the Montréal side they’ve put up a snow dike to try to reduce the danger.

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3 DRMLLL-Montréal – In this sector in Roxboro, we have been fortunate. A channel formed through the ice dam

[Noted in the annotation properties, shown].

 

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4. However, the ice dam is still there and has begun to grow upstream.

 

[DRMLLL-Montréal edits ice dam (embâcle) – see illustration below

 

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5. COR:INRS-ETE has contacted us – they have been working on techniques for ice classification with radar images.

INRS-ETE: We were fortunate enough to get a Radarsat 1 image yesterday from the Canadian Space Agency, who did the preprocessing very rapidly. So, we were able to do our work within 18 hours after acquisition.

With the starting Radar image from CSA, we can readily see the difference between ice and open water, which is black. But it is hard to distinguish between different types of ice, even when we enhance the image.

[INRS-ETE adds “on-the-fly” image enhancement with the Image Style dialog.]

see larger image

 

6. INRS-ETE -- In our technique, we calculate the texture of the image and then classify it. The quality of the classification is improved, and the interpretation done, using ground observation.

Open water is very dark blue. We can distinguish at least four types of ice: light-blue (smoother ice) to deep red (ice jam). We can also see where the concentration of frazil ice is high – as here just downstream of Autoroute 13, behind another area of old ice and ice jam.

 

DGSCSI – Thank you, this gives us a way to develop a general ice map.

 

COR – Now we should decide on some activities to try to mitigate the flooding problem.

see larger image

 

7. COR – Here, downstream from Ste-Dorothée in Laval-des-Rapides, we have a very large ice dam. It is nicely visible on INRS-ETE’s classified image, by the way. We have anther sector with flooding just upstream.

DGSCSI – We should try to do sounding here [uses pointer] to determine if there is still a channel under the ice… Then we can use the barge to try to recut the channel [makes annotation].

 

 

[The teleconference continues to other sectors downstream…]