{"id":27722,"date":"2018-05-21T01:32:51","date_gmt":"2018-05-21T01:32:51","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=27722"},"modified":"2018-05-23T23:52:40","modified_gmt":"2018-05-23T23:52:40","slug":"hidroituango-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2018\/05\/21\/hidroituango-1\/","title":{"rendered":"Hidroituango: another landslide crisis at a hydroelectric dam"},"content":{"rendered":"

Hidroituango: another landslide crisis at a hydroelectric dam<\/h4>\n

Over the last few days another landslide crisis has occurred at a hydroelectric dam site, this time at the large Hidroituango project in Colombia<\/a>.\u00a0 This is a very large embankment dam being built across the Cauca River near to Ituango in Antioquia Department.\u00a0 The dam, estimated to cost $2.8 billion, was due to be completed this year.\u00a0 When operational it will generate 17% of the electricity demand of Colombia.\u00a0 The dam is 225 m high.<\/p>\n

The present landslide crisis is a little difficult to understand as media reports are somewhat confused.\u00a0 The best narrative appears to be in this news report (in Spanish),<\/a> which seems to suggest that:-<\/p>\n

In 2014, Empresas P\u00fablicas de Medell\u00edn (EPM) (responsible for the dam) diverted the Cauca River through two tunnels, each with a diameter of 14 m, to allow construction of the dam.\u00a0 Earlier this year, as filling of the lake began, the water was diverted to a further, larger tunnel 200 m upstream from the first two.\u00a0 The original tunnels were plugged with concrete.<\/p>\n

Unfortunately, three landslides occurred at the site between 28th April and 7th May.\u00a0 These landslides blocked the flow of water, and the lake started to fill to a dangerous level.\u00a0 Concerns started to be expressed that the lake might overtop the dam, triggering collapse. Correction: it is now clear that the tunnel was blocked by a collapse event that propagated to the surface to generate a crater, rather than a conventional landslide.\u00a0 This crater can be seen in satellite imagery<\/a>.<\/p>\n

This image, showing a large landslide scar, is shown in some reports<\/a>:-<\/p>\n

\"Hidroituango\"

A large landslide scar at the site of the Hidroituango site in Colombia.\u00a0 Image via the The Star<\/a>.<\/p><\/div>\n

.<\/p>\n

Meanwhile , the Global Forest Coalition has this image of a landslide<\/a>, probably originating from the scar shown above:<\/p>\n

\"Hidroituango\"

A landslide at the Hidroituango site in Colombia. Image via the Global Forest Coalition<\/a>.<\/p><\/div>\n

.<\/p>\n

The blockage of the tunnel started to cause the water level in the dam to rise, and evacuations were initiated.\u00a0 To try to manage the risk, EPM attempted to dynamite the seals from the original two tunnels.\u00a0 However, progress was to slow, leading to the decision on 10th May to drain the lake through the powerhouse, causing considerable damage.<\/p>\n

But, on 12th May the main tunnel naturally unblocked, releasing a large volume of water that caused extensive flooding downstream.\u00a0 There is a strange video online<\/a> that appears to show an explosive release of water at the site, and a further severe release, apparently at a different location.<\/p>\n