Rivers again - sandbags in the Red River Valley

Last Sunday was World Water Day, highlighting the global issues associated
with this precious resource. But one of those issues is, as with all natural
resources, its distribution, and for the residents of the Red River Valley it’s
a case of definitely too much of a good thing, battling as they are against
rising flood waters. As I write this, predictions are varying, but the river,
along the border between North Dakota and Minnesota and northward to
Winnipeg (it’s sometimes referred to as the Red River of the North to
distinguish it from the Texan one), is likely to crest up to 20 feet above
flood level over the next few days. The residents of Fargo need to fill
two millionsandbags. It is, so to speak, all hands to the pump, with
volunteers coming from all sections of the community - people who have
delinquent fines or outstanding arrest warrants have been given a chance to get
them withdrawn if they sign up for sandbag duty. Three “spider machines,” shown
in the photo at left, above, have been set up to fill sandbags at a rate of
5,000 each every hour, but much of the effort still relies on traditional
methods (photo right, above).

There is geological irony here, for the circumstances that make the valley
prone to disastrous flooding (the 1997 inundation caused $3.5 billion in damages
and required large-scale evacuation) also provide the sand for the sandbags.
During the ice ages, glaciers marauded ponderously across North Dakota and
Minnesota, scouring and sculpting the landscape and leaving vast swathes of
geological debris in their wake. As they retreated and rivers (amongst them, the
Red of the North) re-established their courses, a huge lake built up in front of
the ice - Lake Agassiz, named for the great Swiss-American geologist who
deciphered the stories of glaciation. The map below shows the maximum regional
extent of the waters of the lake - they never covered the entire area shown at
one time, but the position of the lake shifted as the ice retreated. Today’s Red
River follows the western shoreline of the lake, and its wide flat valley
reflects its origins as as an ancient lake floor. Rivers reworked the glacial
sediments and poured huge volumes of sand and gravel into the lake; along the
shoreline, deltas, beaches, and shallow water sandbars formed that today
provide, among many other things, the filling for the sandbags.

President Obama has declared North Dakota a federal disaster area - let’s all
hope that, for the communities of the Red River Valley, sand prevents the
worst.

[sandbagging photos from http://minnesota.publicradio.org/display/web/2009/03/20/fargo_dikes/;
Lake Agassiz map from the Geological Association of Canada, available from the
University of Manitoba Libraries Map Collection, http://www.flickr.com/photos/manitobamaps/2091302531/in/set-72157603391175172/.
For a good summary of Lake Agassiz, see the North Dakota Geological Survey
document at https://www.dmr.nd.gov/ndgs/ndnotes/Agassiz/Lake%20Agassiz.asp] SIGNATURE

Comments

David Bailey (2011-04-08):

Hey,
Thanks! Great post you have written on “Rivers again - sandbags in the Red River Valley”. Really I can say that your post is very informative, I’ll come across your blog again when you will update it with new.
Thanks,
David Bailey

Originally published at: https://throughthesandglass.typepad.com/through_the_sandglass/2009/03/rivers-again-sandbags-in-the-red-river-valley.html