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

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:
Bethel, VT
Re-Photo
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. The flood was caused by a variety of factors.
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.