Editing Three Gorges Dam (section)

=== Erosion and sedimentation ===
Two hazards are uniquely identified with the dam:<ref>{{cite web | access-date=October 8, 2019 | archive-date=November 25, 1996 | archive-url=https://web.archive.org/web/19961125064330/http://earthtimes.org/chinanov11.htm | url=http://earthtimes.org/chinanov11.htm | title=Environmental controversy over the Three Gorges Dam |year=1996 | last=Topping | first=Audrey Ronning | url-status=dead | website=The Earth Times }}</ref> that sedimentation projections are not agreed upon, and that the dam sits on a [[seismic fault]]. At current levels, 80% of the land in the area is eroding, depositing about 40&nbsp;million tons of [[sediment]] into the [[Yangtze]] annually.<ref name="autogenerated1" /> Because the flow is slower above the dam, much of this sediment settles there instead of flowing downstream, and there is less sediment downstream.

The absence of [[silt]] downstream has three effects:
* Some hydrologists expect downstream riverbanks to become more vulnerable to flooding.<ref>{{cite news | archive-date=May 20, 2008 | url=http://chinese.wsj.com/gb/20070829/chw110745.asp?source=baidu | language=zh | script-title=zh:三峡大坝之忧 | trans-title=Concern about the Three Gorges Dam | url-status=dead | work=The Wall Street Journal | date=August 31, 2007 | access-date=August 16, 2009 | archive-url=https://web.archive.org/web/20080520235856/http://chinese.wsj.com/gb/20070829/chw110745.asp?source=baidu}}</ref>
* Shanghai, more than {{cvt|1600|km}} away, rests on a massive sedimentary plain. The "arriving silt{{snd}}so long as it does arrive{{snd}}strengthens the bed on which Shanghai is built&nbsp;... the less the tonnage of arriving sediment the more vulnerable is this biggest of Chinese cities to inundation".<ref>{{cite book | title=The River at the Center of the World | publisher=Henry Holt & Co | last=Winchester | first=Simon | author-link=Simon Winchester | page=228 | isbn=978-0-8050-5508-5 | place=New York | title-link=The River at the Center of the World | year=1998}}</ref>
* [[Benthic]] sediment buildup causes biological damage and reduces aquatic [[biodiversity]].<ref>{{cite book | first1=Henrik | first2=Koen | last1=Segers | title=The River at the Center of the World | publisher=Springer | last2=Martens | year=2005 | page=73 | isbn=978-1-4020-3745-0}}</ref>