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1927 Flood: Then and Now

1927 Flood: Then and Now. Elizabeth Stanley Mann Meghan Kirsch. November 2, 3, & 4, 1927. Approach:. Focus on 1927 Flood in Vermont Collect historic photographs Re-photograph in the same location Calculate Manning’s n for Winooski River. Re-Photographs:. Re-Photo. Bethel, VT.

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1927 Flood: Then and Now

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  1. 1927 Flood: Then and Now Elizabeth Stanley Mann Meghan Kirsch November 2, 3, & 4, 1927

  2. Approach: Focus on 1927 Flood in Vermont Collect historic photographs Re-photograph in the same location Calculate Manning’s n for Winooski River

  3. Re-Photographs: Re-Photo Bethel, VT 1927 Flood Photo

  4. Cambridge, VT Re-photo 1927 Flood Photograph

  5. Montpelier, VT Re-Photo 1927 Flood Photo

  6. Winooski, VT Re-Photo 1927 Flood Photograph Flood Discharge: 118,000 CFS Today’s Discharge: 18,000 CFS

  7. Manning’s n: Roughness Coefficient Manning’s Equation: V = R2/3 x S1/2 / n V = average velocity, m/second. R = hydraulic radius (area/wetted perimeter), m2/meter. S = slope of water surface, no units. n = roughness coefficient Values From: Dam Records, USGS Discharge Records 1927 Flood: 0.02 Today: 0.017

  8. Causes of the 1927 Flood: 150 - 300% rainfall above normal in October Super-saturated soils due to excess rain Late in the season, many plants had died Possibly also due to deforestation

  9. Conclusions: The flood was caused by a variety of factors. The flood greatly changed the landscape, causing failing on slopes, destruction of homes and bridges, and forcing a mass rebuilding effort in all counties. At the observed locations the flood waters were anywhere from 15 to 30 feet above normal levels, depending on the channel geometry.

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