{"id":21543,"date":"2017-02-10T08:20:40","date_gmt":"2017-02-10T08:20:40","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=21543"},"modified":"2017-02-10T08:20:40","modified_gmt":"2017-02-10T08:20:40","slug":"oroville-dam-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2017\/02\/10\/oroville-dam-1\/","title":{"rendered":"Oroville Dam: extraordinary erosion, and a crisis, on the spillway"},"content":{"rendered":"
Oroville Dam: extraordinary erosion, and a crisis, on the spillway<\/h5>\n

The Oroville Dam<\/a> in California is the tallest dam in the USA.\u00a0 with a height of 230 m, this is an earthfill embankment dam built between 1961 and 1968 for the purposes of water supply, hydroelectric power generation and flood control.\u00a0 After years of drought, California is suffering a series of huge rainstorms – so-called atmospheric rivers – that have rapidly raised the water level in the dam.\u00a0 To allow flood control, the dam has been undergoing controlled discharges of water through the spillway.\u00a0 This structure can be clearly seen to the left of the dam in the Google Earth image below:<\/p>\n

\"Oroville

Google Earth imagery of the Oroville Dam in California before the current crisis<\/p><\/div>\n

.<\/p>\n

On Tuesday, after such a release water, major damage was noted on the spillway, apparently caused by the failure of the concrete base and then erosion of the underlying substrate. The California Department of Water Resources<\/a> tweeted this image of the damage on 8th February:<\/p>\n

\"Oroville

Spillway damage at the Oroville Dam, via California Department of Water Resources<\/a><\/p><\/div>\n

 <\/p>\n

Over the next few days further discharges of water have been undertaken to test the spillway and to control the water level in the lake. The CaDWR tweeted this image of one such test earlier today:<\/p>\n

\"Oroville

Damage to the Oroville Dam spillway during a water flow test on 9th February, via CaDWR<\/a><\/p><\/div>\n

.<\/p>\n

Unsurprisingly, the condition of the spillway has dramatically deteriorated:<\/p>\n

\"Oroville

Damage to the Oroville Dam spillway on 9th February, via CaDWR<\/a><\/p><\/div>\n

.<\/p>\n

So now the Department of Water Resources are left in a bind.\u00a0 KQED is providing excellent coverage of this event<\/a>, with an update yesterday as follows:-<\/p>\n

With the spillway mostly out of commission since major releases were curtailed, Lake Oroville has been rising at the rate of about half a foot [about 15 cm] an hour since midday Tuesday. Its level has increased 30 feet\u00a0 [about 10 m] since then, with the reservoir\u2019s surface now 20 feet [6 m] below an emergency spillway.<\/p>\n

The emergency spillway, which would release water down a steep slope adjacent to the spillway, has never been used in the dam\u2019s half-century of operation. DWR officials and others say water flowing down the slope will likely result in a large volume of debris being dumped into the Feather River, which flows through the city of Oroville on its way to the Sacramento Valley.<\/p>\n

That\u2019s one reason dam managers are willing to risk the destruction of the concrete spillway, calculating that would be preferable to the unknowns involved in an uncontrolled emergency spillover.<\/p>\n

\u201cIt\u2019s going to be rocks, trees, mud \u2014 liquid concrete \u2014 going down that river,\u201d retired DWR engineer Jerry Antonetti told Sacramento\u2019s KCRA as he watched the spillway Wednesday night. \u201cI\u2019d open \u2018er up, sacrifice the bottom of that thing \u2014 it\u2019s going to go in the river \u2014 clean it out next year and build a new spillway.\u201d<\/p><\/blockquote>\n

The emergency spillway can be seen to the left of the main structure in the image below:<\/p>\n

\"Oroville

Google Earth image showing the main spillway and the emergency spillway at Oroville Dam.<\/p><\/div>\n

.<\/p>\n

It is not difficult to anticipate the damage that the use of this structure will cause.\u00a0 Fortunately the integrity of the Oroville Dam itself is not in question, but managing the spillway and associated damage is a massive challenge.<\/p>\n","protected":false},"excerpt":{"rendered":"

At the Oroville Dam in Calfornia an extraordinary crisis has developed as the spillway undergoes massive, flood-induced erosion<\/p>\n","protected":false},"author":22,"featured_media":21568,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[137,71,325,469,59,725,48],"class_list":["post-21543","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-california","tag-dam","tag-erosion","tag-featured","tag-flood","tag-north-america","tag-usa"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/21543","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=21543"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/21543\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/21568"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=21543"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=21543"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=21543"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}