Anatomy of a Landslide Dam

Landslide dams are a cascading hazard. Landslides themselves can impact people and property, but when their debris blocks streams and rivers, the dams and impounded reservoirs they form can pose a secondary hazard to people and infrastructure downstream, when they fail and release water and debris.

Last year the Kaiwhata landslide, located east of Wellington in the Wairarapa, created a dam and reservoir. Soon after its formation, the dam breached and the reservoir emptied, which sent a flood wave downstream inundating the area with water and debris. Last month the landslide reactivated following a heavy rain event, and formed a new landslide dam and impounded reservoir, which is still present (as at December 2020).

[howaboutataste]

I remember as a kid when there were down trees in the creek we would make a dam. All you need is a good log or two and then bring downed branches to it. The leaves would collect and slow down the flow of water remarkably. The water level upstream would rise until it flowed over. After several days the water level would be increased some distance upstream, with it being still and clear water. Also our parents would make us disassemble the dam at that point, or whenever they became aware of it. Which was also sort of fun but could be a heavy task. There's quite a lot of weight on it at that point and figuring out how to dismantle it was an exercise.

[alvonfinster]

Thanks, nice & concise. I live in the Yukon, and we have many failures of this sort - large and small. Melting permafrost is adding to the extent & intensity of slope failures. Most are not described - too large an area, too few people. I was involved in the fisheries, specifically salmon habitat. The failures can negatively affect upstream migration and the downstream deposition can form/destroy downstream spawning and rearing habitats.

[person]

Post10 would have had that blockage opened within the hour.

[OVTraveller]

So typical of bureaucracy: investigate, express concern, assessment, The solution was so evident from word go, so let the built up waters erode the landslide, sit back, go back to your office declare the disaster over!

[anandlahane]

Impressively informative.
In India, , had we had such dedicated studies and monitoring, the Kedarnath havoc could have been avoided .
May the souls rest in peace.

[warphonesS]

Not one person thought oh the water has reached the top of the dam. Let's put a camera to film the breach in all its glory.

[KiarashPooladsaz]

Working on this case study for my thesis, this video is informative, patiently describing the event and it is so clear! Great team work.

[keyboardwarrior]

Great video, very interesting and informative. Keep it up!

[vice.nor.virtue]

This is such a great video to show to students who may be interested in persuing a career in Geography. It was really interesting how they documented this dam.

[jessed]

good lord two weeks without action and the rain solved the problem with the obvious answer. dig a trench and let the water do its thing.

[emmaathome]

Dam forms, dam erodes, water flows..there you go.

[fullcircle]

First time I heard of this and I'm in NZ. Thanks for the video.

[xzysyndrome]

Kinda bummed no one had the forethought to set up a camera to video the breach and emptying of the lake.

[johnprentice]

Having had a previous landslide in the area I'd suggest it's potentially a dangerous area to be working in and collecting the data finding research. Hats off to you guys stay safe and thank you for your excellent video.

[philipgarsidebooks]

I'm enjoying your videos. Very clear descriptions of what happened and why.

[DonLuc]

Super video, brief, concise, informative, no background music, that makes it about perfect! Just stumbled onto your site.

[justold]

Yep, Mother Nature Happens (every day) !

[assassinlexx]

So call up the blasting crew. They can blow a cut to drain the back up river.
But instead it is talking talking talking. More real action not lip action.

[josephthibeault]

Much can be done if you are actually doing something.
The lake should not have been allowed to grow this size.
Need someone in charge.

[Nowa]

WHAT A BEAUTIFUL MOMENT... And I'm here - you come in too