Canada Dam Emergency – Value.Space Assessment

Instability confirmed on a dam deemed at risk of failure by authorities in Quebec, Canada.

December 12, 2023

At 10:09 PM on December 3, 2023, Quebec's Public Security Ministry issued an alert regarding the potential failure of the Morier Dike. Residents of Chute-Saint-Philippe and Lac-des-Écorces were given preventive evacuation orders.

To date, more than a thousand people have been evacuated. In the event of the dike failure, an estimated 2,000 buildings could be impacted, according to flood maps.The Morier Dike, constructed in 1954, holds a reservoir capable of retaining up to 382 million cubic meters of water, equivalent to more than 100,000 Olympic-size swimming pools.

Local media referenced Quebec’s Environment Ministry, which is responsible for the dike, that a routine inspection had revealed the dam's stability might be compromised, likely because of internal erosion. Emergency work is currently underway to reinforce the dam against possible failure.

Value.Space’s Assessment of Morier Dike

Value.Space conducted a satellite-based risk assessment of the Morier Dike, analysing the dam's structural behaviour for an 18-month period prior to the instability discovery on-site. Timeline: May 10, 2022, to November 13, 2023.

Figure 1 – Finds on the Morier Dike

All finds on the Morier Dike

The assessment revealed seven significant and notable movements on the dam, which can indicate structural weaknesses that existed or developed during the period of the analysis.

Figure 2 – Significant Find

Significant find on the Morier Dike

  • Find 03 - the movement stands out due to being different from the adjacent areas on the dam slope. While the data clusters on the top of the dam indicate lift, there is downward movement on the toe of the dam. Movements with different directions across a dam section can indicate structural weakness.

  • Data timeline shows that change of stability in this section occurred from February 2023 onward. The movement velocity is up to 22.12 mm a year.

Figure 3 – Notable Movements

Notable finds 01 & 02 on the Morier Dike

  • Finds 01 and 02 – both areas of movement extend from the top of the dam to the toe of the dam, across the structure. Again the movement areas stand out compared to stable dam sections on either side.

  • The downward movement in the section represented by Find 01 reaches up to 30,87 mm a year. Similar movement on the section represented by Find 02 is up to 22.24 mm a year.

The rest of the finds (04, 05, 06 and 07) indicate movement areas on the slope or on the top of the dam, that add to the overall picture of structural instability of the Morier Dike. The movement of the find-areas are between 19-22 mm per year.

Morier Dike Instability Confirmed

Several finds on the dike indicate movements across the dam sections that are between stable sections of the dam, which can be signs of a weakening dam structure and would need to be looked at by engineers on-site. The overall picture of the Morier Dike as revealed by Value.Space’s assessment can be seen as similar to past examples of dams that eventually failed.

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