Thursday, December 08, 2005

Marvel's dips into the Antietam

The January 2006 article of America's Civil War magazine has an article written by William Marvel on the subject of the possible usefulness of the creek crossings on the Union left flank during the battle. The author waded through the creek himself and recorded the depth at various places. He seems to make the quite reasonable assumption that the flow today is about the same as it was back in 1862. What makes me think twice about this is an episode of Battlefield Detectives I watched a few nights ago that investigated the Revolutionary War battle at Oriskany. The cartographer/geographer was puzzled why the raging creek of today on a key area in the battlfield was not noted on period maps. After studying the problem, he posited that the considerable deforestation and other vegetation losses in the intervening years led to a high erosion situation that resulted in a far greater volume of free water flowing into low lying areas. Thus, rivulets are transformed by the increased runoff into creeks and creeks into small rivers and so forth. Makes me wonder if Marvel took this possibility into consideration.

3 comments:

  1. Drew,

    I did take that into consideration. I anticipated higher water volume because of greater pavement coverage, etc., but diverted tributaries and drainage retention in surrounding development seems to have minimized that effect. I also chose a day when water levels were similar to September of 1862 (against the bridge abutments), and interviewed a Hagerstown native and fisherman who said the creek had not changed much in depth since his youth (presumably in the 1930s.

    Bill

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  2. Mr. Marvel,
    Thanks for visiting and for your clarifying comment. It sounded like a fun hands-on-history project that should stimulate discussion among enthusiasts of the battle.

    Cheers.

    Drew

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  3. Having watched the rocky streambeds on my own family's property (and downstream at the creeks) shift over nearly four decades, I find the assumption of things being the same speculative. 143 years is a long time for a creek. The approach isn't necessarily wrong, but it needs quite a bit of cross checking and verification.

    Water moves mud, sand, gravel and rocks over time. It fills in old holes and channels and gouges new ones. The big changes to the beds occur during high flows in my experience. (Beaver also tend to have an impact in some locales in the West/South creating water retention and flooded timber, etc.)

    Even going back to the 1930's is not far enough to really know. Of real relevance would be the several decades before 1860. If the land use changed much in that time, then the water runoff/retention likely would as well. In a few decades this could change the character of the creek bed considerably. So by 1880 it might be substantially different, and 1930 is still quite far in the "future."

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