This kinda ties into the last entry, which discussed the historical context of hurricanes (a.k.a. tropical cyclones if you follow the research literature) in the Ithaca area. Irene, while it had devastating impacts in some towns in the Capital Region and the Catskills, left Tompkins County with 1-2 inches or rain, hardly more notable than a particularly rainy summer day. I went down to southern Connecticut to enjoy being exfoliated by high winds on a beach, and a decent though not amazing storm surge. Then I came back to my Albany home to find roof damage, and a 60-foot ash tree that crashed down in front of the duplex across the street and on top of a Honda Civic. I’ve had better weeks, meteorologically speaking.
As I mentioned previously, the two worst floods in Ithaca occurred quite a long time ago – in 1857 and 1935. However, this is not to say that Ithaca hasn’t been flooded in modern times. The flood control channel down by Cass Park is there for a reason. Also, here’s a youtube video that starts with the flooded intersection of Mitchell and Pine Tree next to East Hill Plaza from way back in December 2010.
But comparatively, that’s small potatoes to some of the floods Ithaca has seen. The 1857 flood was massive. It also hails from a much different time in Ithaca’s history, before the colleges, and when the town itself had a few thousand people. Although sources are severely lacking, the downtown area was underwater for several weeks. This was before the era of effective flood control, and since downtown Ithaca is basically surrounded by steep hills on three sides and a lake on the fourth, the drainage system is about as far from optimal as you can get. Add to that some relatively impervious soil, and it becomes a big soggy problem.
Flooding is not unlikely with the spring thaw, or rapidly evolving early winter storm systems that start off with a warm moist tongue of air, dumping heavy rains before the area freezes over (certifiable proof that Mother Nature hates us all). But the two worst floods are summer events – June 1857 and July 1935, respectively.
The flood of June 17, 1857 seems to be the result of a highly localized warm-season precip event directly on the Six Mile Creek watershed (the creek just south of the Commons), which gives me the impression of a wet microburst or a cloudburst type of event. Both tend to be local and related to intense thunderstorm activity (and here’s a fun thought for when you go to sleep – they are notoriously difficult to forecast, and microbursts are one of the biggest reasons planes won’t land near thunderstorms). Anyway, the raging torrent washed out two dams, whose debris then slammed into the Aurora St. bridge, collapsing its stone arches and sending the whole shebang surging through the town. Hell, you can quote Dear Old Ezra on that one.
Some measures were taken to improve flood control, including more or bigger dams (like the one on Beebe Lake in 1898), and these were damaged by further floods, including events in 1901 and 1905. But nothing quite prepared the ares for the disaster that was the July 1935 flood.
The July 8, 1935 flood, from the descriptions I can find, seem to indicate an intense and prolonged mesoscale convective system (big effin thunderstorm complex), or something of similar intensity, with tropical moisture but nothing TC-based. At the very least, it was definitely associated with evening thunderstorms on the evening of July 7th, in an area spanning from Hornell to Binghamton.
The 24-hr. rainfall total of 7.9 inches in Ithaca (the weather station was on the Ag Quad) is impressive. The local creeks almost immediately began to flood, and as drainage brought more water through the streams, they began to tear away at their banks, and flood Cayuga Lake downstream. The damage went throughout the county, from homes washed away in Enfield to cottages being washed from the lakeshore up by Trumansburg. A passenger train was stranded, and all the train tracks in the county were washed out or impassable due to debris. Most state parks in the area were badly damaged and downtown was once again flooded. Eleven people lost their lives in Tompkins County as a result of the flood (with 52 being lost in total, and $26 million in damage [1936 dollars, equivalent to $409 million today]). The damage to Ithaca was about $1.8 million in 1936 dollars, or $28 million in 2009 dollars.
As for the university, being on higher ground protected it from the wrath of the waters. Barton Hall was used as an emergency shelter for almost seven hundred people. The damage to campus was estimated at $10,000-$12,000 (1936 dollars, about $250,000 today), mostly due to the hydroelectric plant being flooded and some trail and bridge damage.
So, maybe it’s not on a Biblical scale, but there’s something to be said about living on higher ground and away from creek banks in the Ithaca area. Or you can just look at the Beebe Lake Dam after a good rainstorm to get a faint idea of how much worse it could be.