Earthquake Dam, Linton New Zealand

During the earthquake the slopes collapsed and triggered many many landslides. The total area affected by landslides is about 7,000 square kilometres so it’s a huge area so mapping that area takes a lot of time. So we’re about 10 kilometres west of Kaikoura there’s been quite a large landslide that has filled the river and has dammed it. This is one of about fifty landslide dams that we’ve identified to date but there will be more of varying volumes varying sizes some of which might pose a hazard and therefore risks, some maybe just so small that nobody will even notice. What you can see is the head scarp of the landslide which is the bare area and you can see the vegetated area that’s kind of the forest that has slumped down as the earthquake caused the land to collapse and what you can see now is the bottom or the toe of the debris which is the very bottom where the debris has filled in the drainage line and further above the dam you can see the lake is starting to form and this is the problem. The water now is being impounded behind the dam. As the dam starts to fill there is potential that the dam can actually fail. Natural dams can fail for multiple reasons. They can fail because the water in the reservoir behind the dam overtops and erodes the dam out. They could fail because another landslide comes down and completely destroys the dam or they can fail as water seepage passes through the dam and causes headward erosion which can eventually undercut and undermine the dam. So if the dam were to collapse then downstream is the bridge for the inland road into Kaikoura and also there is a small school lower down and several farm buildings so what we’re doing now is we’re trying to get a much better understanding of the shape of the dam how wide it is how high it is what the material is like what the volumes are and the lake level. If we assume that the dam were to fail and the water and debris travels down the slope we can then get a better understanding of how far the debris is going to go and the height of inundation and the velocity of the debris. So in order to kind of like kind of measure and survey the debris and the volume of water what we need to do is we need to use a combination of instruments and so what we’ve got now is a drone and the drone we use photographs from and we create a real model of the ground. And then over there is the laser scanner which is like a ground-based laser and all it does is it fires a laser beam off a slope and measures the time and from there we can create a model. We can then bring the photographs together with the laser and create a very accurate picture and this is the base data that we use for our calculations of what would happen or what could happen.

5 thoughts on “Earthquake Dam, Linton New Zealand

  1. I must compliment the producers of this video as it gave a very good description in layman terms of what did, is, and could happen in this situation. Thank you.

  2. Seems to me if you're going to spend thousands of dollars surveying it all, why not take that money instead and get a couple earthmovers up there and clear the dam before it fills with water.

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