I’ve lived in New Hampshire my entire life and whenever we get ridiculous amounts of rain (Hurricane Irene, right now) I always hear about Vermont getting washed away while we have some sporadic bad flooding here in New Hampshire. Is there a reason (like terrain) that Vermont floods so much more than us? Or is it that it has happened to flood more in my short 21 years of life?
*My heart goes out to the Vermonters here right now* 💙
In: 66
The geology (and thus geography) of Vermont is somewhat different. It is more of a fold belt running north-south, so it tends to have narrow valleys between high uplands. The geology of upstate NH is dominated by intrusive rocks and lacks that linear ridge-valley system; southern NH is more like southern Maine/eastern Mass and has wider valleys or rolling terrain. The more eastern “linear system” equivalents occur up (north) toward the eastern townships region of Quebec and miss NH (those parts of Quebec got whacked pretty well too, much like Vermont). The “belt” passes n-s through Vermont before turning ne-sw through quebec (townships through Gaspé and out toward Newfoundland). A little more complicated than that, but the general idea applies.
The thing about watersheds is that narrow valleys see rise in water levels a lot faster than wide watersheds. The volume has to be accommodated somehow, and if it isn’t over a large area, it has to be by increased height. It will rise until it can spread out, basically. Well, Vermont geography has a lot of places where there isn’t a large flatland where the water can spread out easily. Not all Vermont, but enough places that particular rivers always rise a lot with heavy rain. New Hampshire does have such narrow valleys too, but it is a lot less important part of the total area, so major flooding is less common.
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