Wednesday, April 11, 2012

Great Imponderables of the canal system: 1

Unlike Stephen Fry, there are several things I do not know.  One of them is this: Why does it always rain in Crick tunnel?

You can tell experienced boaters as they pass southwards through Crick –they are putting on their raincoats on a sunny day. After goodness knows how many drought months we have had, if you go through that tunnel today, you will get more than a drip or two down your neck.  Well that was true a week ago at any rate because I was there.  In Crick tunnel it rains every day of the year.

Now that bit of the canal is the highest watercourse in the area.  It is the summit section that feeds downhill at its ends through steep staircases at Watford and Foxton.  Admittedly the ground does rise to the east , but only by some 20 metres in a mile or so and then it goes downhill again.   To the west is a similar rise about half a mile away. Here’s my artists impression (O level Art grade 5 1964, second attempt)

crick tunnel

Here we see the tunnel mouth as approached from the north.  Can it really be that that measly bit of ground over the top has held enough of its own water for a dry 18 months to still be dripping into the tunnel?  It could be coming downhill from  the left of the picture, but there isn’t that much land up there. 

Short of there being a leaky pipe up there ( I doubt it) I can’t think of any other explanation.  But it still amazes me that there is enough water up there to make continual rain in the tunnel.

Or could it be condensation??  It is pretty cool and clammy in there.  Maybe that’s it. 

We should be told.

1 comment:

Bobr said...

It is condensation, we have an old railroad tunnel with an old work shaft coming down in the middle and it has been raining in there for 150 years. Its in the mountains of South Carolina USA.