{"id":18106,"date":"2016-03-24T12:30:23","date_gmt":"2016-03-24T12:30:23","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=18106"},"modified":"2016-03-24T12:30:23","modified_gmt":"2016-03-24T12:30:23","slug":"the-yale-himalaya-initiative-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2016\/03\/24\/the-yale-himalaya-initiative-1\/","title":{"rendered":"The Yale Himalaya Initiative landslide hazard map for Nepal"},"content":{"rendered":"
The Yale Himalaya Initiative landslide hazard map for Nepal<\/h5>\n

An article by the Yale Himalaya Initiative<\/a> has announced the development of a new landslide hazard map for Nepal.\u00a0 This map, below, was built by a team who “created a model to identify high-risk areas. Their model incorporated elevation, aspect, slope, roads, population centers, rainfall patterns, and drainage systems<\/em>.”\u00a0 It appears that this was based upon a more local scale approach used by ICIMOD<\/a>.\u00a0 The resultant map divides the country into four hazard classes:<\/p>\n

\"Yale

The Yale Himalaya Initiative landslide hazard map for Nepal<\/p><\/div>\n

.<\/p>\n

The article claims that the technique has remarkable skill in identifying areas of high hazard.\u00a0 One of the team, Ross Bernet, is quoted as saying:<\/p>\n

\u201cOur model is 84-percent accurate based on the data we had…We\u2019ve said, \u2018Here\u2019s where we found the data, here\u2019s what we\u2019re working with, here\u2019s what we did.\u2019 The hope is that someone who might be using the map to make decisions that affect people\u2019s lives really understands all of that.\u201d<\/p><\/blockquote>\n

On the face of it this is very laudable, but I have reservations.\u00a0 think a few key points are pertinent here.\u00a0 The first is that one needs to be very careful to define terminology.\u00a0 In particular, the use of the terms hazard and risk have particular meanings in this context, and they should not be used interchangeably.\u00a0 It is far from clear to me as to whether this is a hazard map or a risk map (the inclusion of population centres may indicate the latter?), or maybe a susceptibility map.\u00a0 Second, it is really important to be clear about which type of landslide trigger is being discussed.\u00a0 Seismically-induced landslide hazard will be different from that for rainfall, so which is being accommodated here?\u00a0 Given that seismic hazard is not included as an input, it would seem it is just rainfall induced landslides, but the inset map suggests that the landslide inventory was for seismically-induced failures. And third, great care must be taken with statements about accuracy.\u00a0 I could decide that all of Nepal is high hazard, and claim to be 100% accurate because all of the landslides are in my high hazard zone.\u00a0 But this is meaningless of course.\u00a0 Defining what is meant by accuracy is really important.\u00a0 We must not get into a situation in which decision makers think we can assess the hazards of landslides with very high levels of accuracy.\u00a0 We simply cannot at present, and that is not for a lack of trying.<\/p>\n

A second key issue for me is that this work appears to be presented in isolation.\u00a0 Bu this is not the first national scale landslide map for Nepal.\u00a0 The Nepal Hazard Risk Assessment<\/a> (NB the link is to a PDF) project of a few years ago, which was led by a very credible and experienced international team who really understand both landslides and risk, undertook a detailed assessment of a range of hazards in Nepal, including landslides.\u00a0 They generated two maps of national landslide susceptibility (not hazard or risk).\u00a0 This one for rainfall-induced landslides:<\/p>\n

\"Yale

The Nepal Hazard Risk Assessment Project<\/a> map of rainfall induced landslide susceptibility<\/p><\/div>\n

.<\/p>\n

And the other for seismically-induced landslide hazard:<\/p>\n

\"Yale

The Nepal Hazard Risk Assessment Project<\/a> map of seismically-induced landslide susceptibility<\/p><\/div>\n

.<\/p>\n

There are huge differences between these two maps of landslide susceptibility, and between these maps and the one generated by the Yale Himalaya Initiative.\u00a0 There is a real danger of confusion here, which I find very worrying.<\/p>\n

I have been collecting data on landslides that kill people in Nepal for 16 years.\u00a0 Technically this is of course the realisation of landslide mortality risk (and I note that the Nepal Natural Hazard Risk project maps do not show risk – I am unsure as to whether this aplies to the Yale Himalaya Initiative map as well), .\u00a0 Below is a map of fatal landslides across Nepal for example from my data (these are all rainfall-induced landslides):<\/p>\n

\"Yale

Map of fatal landslides in Nepal from my fatal landslide database<\/p><\/div>\n

.<\/p>\n

There is a notable difference in the location of these landslides and the landslide hazard map from the Yale Himalaya Initiative.\u00a0 The Nepal Hazard Risk Assessment Project appears, at least superficially, to explain the distribution much better.<\/p>\n

I realise that I might sound overly critical in this post – that one could take the view that every initiative of this type is a good thing.\u00a0 And I recognise that this work is built upon the strengths of ICIMOD.\u00a0 But releasing a map into the wild like this without providing an explanation for what it actually shows and how it was derived feels unhelpful.\u00a0 This feels even less satisfactory when high levels of accuracy are claimed but are not explained or justified.<\/p>\n

Landslide hazard mapping is deeply challenging.\u00a0 There are no simple fixes in my view,<\/p>\n","protected":false},"excerpt":{"rendered":"

The Yale Himalaya Initiative has generated a landslide hazard map for Nepal. it is very unclear as to what this map is actually showing. <\/p>\n","protected":false},"author":22,"featured_media":18115,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[558],"tags":[499,469,503,66,246,72],"class_list":["post-18106","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-development","tag-disaster-risk-reduction","tag-featured","tag-hazard","tag-nepal","tag-risk","tag-south-asia"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/18106","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=18106"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/18106\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/18115"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=18106"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=18106"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=18106"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}