10 June 2008
Tangjiashan – problem over
Posted by Dave Petley
Xinhua is now reporting that the flood wave has passed through the city of Mianyang safely. This appears to mark the end of the crisis. I have to say many, many congratulations to the Chinese authorities and everyone involved for their handling of this event. To manage to mitigate this lake in this way is probably an unprecedented achievement.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
The mayor of sichuan had declear dismiss of the alarm a whle a ago as the level became about 720m and the water wave passed Mianyang safely.P.S.An interesting observation to me was that the channel widen itself much faster than cuting deeper. That might explain that the dam releases pressure quickly without weakening itself too much.
Dear Dr. PetelyYour readers may wish to to gain further insight to the effects of the 12 May EQ on Chinese infrastructure by using Google Earth and the KMZ file available from the Google Lat Long Blog which contains layers for pre- and post-EQ imagery available at http://google-latlong.blogspot.com/2008/05/imagery-for-sichuan-china-earthquake.html Note that georegistration is not perfect in these images.One downstream dam called Kuzhu in other Xinhua news photos was already destroyed before water was released from Tangjishan Lake. The dam’s coordinates are 31.84 N, 104.448 E (Google Earth)To see what this hydro power site looked like before the EQ turn on the “before” imagery in the KMZ file above. Post-EQ/pre-Tangjishan Ll flood pictures released by Xinhua of the dam and reservoir are available at http://news.xinhuanet.com/english/2008-05/25/content_8251172_2.htm and http://news.xinhuanet.com/english/2008-05/28/content_8271237_1.htm For a good satellite view of Kuzu dam and power station after the quake but before it was “over topped” by flood waters from L. Tangjishan select the layer “after/2008-05–15/Panchromatic”. Note because of imperfect georegistration the apparent lat-long of Kuzu dam is 31.385 N and 104.454. Water backed up from another landslide dam just down stream (apparent location in the panchromatic image is 31.8433 N, 104.466 E) has already flooded the power house.In these same images (I like the multispectral image of 2008-05-14 best) one can see 4 more landslide dams blocking the river in the next few miles down stream. A significant volume of these slides will be added to the sediment in those from Lk Tangjishan swept down stream. Toggle between pre- and post-EQ imagery to form your own estimate of infrastructure damage.Jim S.
water water everywhere includes some very nice high resolution pictures of the scene.
Confused media:In many websites, the location of Tangjiashan Lake is shown in wrong place:http://news.bbc.co.uk/2/hi/asia-pacific/7404614.stmhttp://www.chinadaily.com.cn/china/2008-06/11/content_6750951.htmThe lake (marked as “Lake”) shown in this image is the correct one.http://bp2.blogger.com/_a2JvElU8gh4/SDKEOil8B-I/AAAAAAAAAKs/bx6010E4MUY/s1600-h/08_05+beichuan+annotated+image.bmp