Monday, April 21, 2014

Mississippi Dams


Image Credit - US Army Corps of Engineers.  The image shows the 18 dams and locks on the upper Mississippi River.  These dams and locks were built to create a fully navigable river channel.

Earlier this year, when we spoke about river deltas and the problems facing them.  One such problem is hydroelectric and flood-control dams.  These structures trap sediment on their upstream side.  It's estimated that only about 10% of the total sediment entering the water in the Mississippi Watershed actually makes its way to the delta.

Heres a linked article from New Scientist indicating that the Mississippi Delta, home to a large population and a significant oil & NG exploration industry, will have enough coarse sand for centuries to come.  Of course, the amount of silt and mud dropped as soon as the dams were constructed.

Interesting premise...
http://www.newscientist.com/article/dn25438-mississippi-dams-arent-to-blame-for-flood-risks.html#.U1U3xfldV8E

Wednesday, April 9, 2014

A New Island Forms - Plate Tectonics in Action!

File:Surtsey eruption 1963.jpg
Image of Surtsey appearing south of Iceland in 1963.  Image credit - Wikipedia


Check out the linked article on NASA's Earth Observatory about a new island that appeared in the neighborhood of Japan, right next too an island that formed in the mid-1970s.

Earth Observatory - New Article