Driving down Needham St a few days ago I noticed a curious and (so far) inexplicable phenomenon.
If you stand on the Needham St bridge over the Charles River and look upstream you’ll see that the river is frozen. That’s not a big surprise given the recent chilling weather.
If you look downstream from the opposite side of the bridge you’ll see that the entire river is water, not ice.
So the mystery is what’s causing this sudden thermal transition in the river, right at the Needham St bridge.
There’s one possible clue that I could see. Right beside the bridge a small non-frozen tributary comes out of a culvert under Oak St and joins the main river. I’m pretty certain, this tributary is South Meadow Brook. That small brook goes past Countryside School about a mile way, crosses Needham St about half way down and then appears/disappears below ground a few times before joining the Charles River at the Needham St bridge.
If this little brook is what’s melting the Charles at the bridge it would have to be very warm water, especially because there’s not much volume of water in the brook. There’s no reason you’d expect this little brook to not be frozen. I didn’t check to see if the brook is frozen further upstream.
So all you amateur hydro-thermologists, here are my questions.
1. Is the brook melting the river
2. If so, what’s heating the brook water
3. If not, what’s melting the river water
If anybody happens to be on Needham St today, take a look at where the brook crosses under Needham St (by the RR tracks and Jiffy Lube) and let us know if it’s frozen up there.
Since the response so far has been underwhelming, I’ll throw out two possible theories.
#1 My theory is that perhaps the riverbanks on the downstream side of the bridge are a bit narrower. That, and the added water from the brook causes the water to flow faster. The higher speed of the flowing water makes it harder to freeze and we just happen to have the right conditions to make the ice/water line right there.
#2 My daughter’s 11 year old friend Mari Jackson says “What if that’s the invisible border between two weather regions and its warmer in one than the other” Sort of like the winter weather forecasts around here – 3-6 inches of snow inside 128, 6-12 outside 128.
I think I’ll go with theory #2, not because its more credible but because I just like the idea of it.
Dripping road salt?
The not-yet-discovered Needton hot springs?
All other thing being equal, there’s the pulling motion of the falls just below where youre seeing this.
The falls at the mill is just about a mile downstream from Needham St, so it probably doesn’t have to0 much of an effect that far upstream … but that’s still probably as good a guess as any of the others we’ve got so far,
If the brook travels underground, then I would have to say that there is a little geothermal action going on. If not, then I would have to go with some sort of higher temp runoff. Lastly, if neither of these is a factor, then Jerry has a great point. Faster water freezes slower, and thaws faster.
My guess is that it’s the water from the culvert. There are similar hot spots on the Charles in the Cambridge stretch – as a student, we were very aware of their locations when we were idiot enough to walk across the frozen river to Boston.