How does the Kennet & Avon stay wet??

[jetzi]

I was browsing the CaRT canal map looking at the Kennet and Avon. As I was following the route climbing the numerous locks from Reading to Devizes I noticed a curious thing.

 

At the Bruce Tunnel, the locks turn around and you start going down again!

Obviously, this is something that has to happen when a canal goes over a hill. But how on earth does the canal not quickly run out of water? It doesn't appear to be fed by any rivers, and I'd be amazed if that much water could be provided just by rain. Is it pumped? If so, from where?

 

[Tony Brooks]

Wilton Water and pumps. Now electric (when they are serviceable) but also the Crofton Steam pump. Wilton Water is to the right of your map and a bit further south. I don't know for sure but suspect back pumping is involved as well. One of the K&A chaps will be along soon to clarify.

[Jen-in-Wellies]

Crofton Beam Engines. The original method, to pump water up from the river below as Tony says. Further to the west, not far from Bath there is the Claverton Pumping Station, that uses a water wheel to pump water up from the Avon. Clever people these Regency engineers. Very embarrassing when your new canal runs dry, so they thought it through and planned to have water where it was needed. Most times they succeeded. Some times they didn't....

 

Jen

[jetzi]

Another one at Tring. I don't know why this challenge never occurred to me before ?

 

Edited August 21, 2019 by ivan&alice

[MtB]

 

Most people never think about it, and imagine the canals stay full of water by pure chance.

 

And think CRT's main function is to mow the grass and fix the lock gates. 

 

 

[jetzi]

9 minutes ago, Mike the Boilerman said:

Most people never think about it, and imagine the canals stay full of water by pure chance.

 

And think CRT's main function is to mow the grass and fix the lock gates.

We were cruising near Hemel Hempstead last weekend and most of the bridges had "F*ck CaRT" graffiti on them.

 

We were half seriously talking about changing them all to "We love CaRT" and "Thanks CaRT".

 

They have never been anything but kind and helpful to us in all our dealings. And having just bought our next years' license for only 1040.2 gbp, I have to say I think they do a lot with very little funds. I'm sure I've utilised a grands worth of water, locks and mown grass in a year. Not to mention the elsans, rubbish disposal and water points.

[Tony Brooks]

23 minutes ago, ivan&alice said:

Another one at Tring. I don't know why this challenge never occurred to me before ?

 

 

 

Again look at the blue bits on the map. When you see lakes close to a canal they are almost certainly reservoirs built to feed the canal.  In this area of the GU they also pump water from underground sources.

 

If you look at the summit level of all (as far as I know) canals there will reservoir lakes around. Exceptions are the Welsh canal which is fed by the river Dee and the Shropshire Union that is fed by Wolverhampton sewerage works. Probably others as well.

[Jen-in-Wellies]

11 minutes ago, Mike the Boilerman said:

 

Most people never think about it, and imagine the canals stay full of water by pure chance.

 

And think CRT's main function is to mow the grass and fix the lock gates. 

 

 

Most people now know that CaRT has at least one reservoir.  ?

 

4 minutes ago, Tony Brooks said:

Exceptions are the Welsh canal which is fed by the river Dee and the Shropshire Union that is fed by Wolverhampton sewerage works. Probably others as well.

The summit level of the Sheffield and Tinsley is now fed by pumps from the River Don. Originally it was fed by a feeder from the River Sheaf, similar to the River Dee and the Llangollen branch, but that was lost when Sheffield Midland railway station was built. After that it was fed from water pumped from coal mines, until they were closed.

[Tacet]

How to fill and keep filled the summit level taxed the original canal builder.  The summit level could be no higher than could be supplied - hence tunnels and cuttings were used where needed.  

 

The preferred solution was to use or divert an existing stream.  Pumping water from lower levels was to be avoided due to complexity and expense   

[dmr]

Getting a good water supply was one of the real big issues when canal building, it influenced the route and dictated the use of expensive summit tunnels.

 

K&A fed from Wilton Water just below the summit on the Eastern side, Steam engines at Crofton raised this to the summit where it flowed both ways. Wilton Water is a small lake and spring.

 

Western End fed by a clever water driven water wheel taking water from the river Avon up to the Bradford to Bath pound.

There is now extensive back pumping so water can be moved long distances, the Avon water can even go over the summit to supplement the Eastern end if required, though extraction of Avon water is limited.

 

.............Dave

[Tim Lewis]

1 hour ago, ivan&alice said:

I was browsing the CaRT canal map looking at the Kennet and Avon. As I was following the route climbing the numerous locks from Reading to Devizes I noticed a curious thing.

 

At the Bruce Tunnel, the locks turn around and you start going down again!

Obviously, this is something that has to happen when a canal goes over a hill. But how on earth does the canal not quickly run out of water? It doesn't appear to be fed by any rivers, and I'd be amazed if that much water could be provided just by rain. Is it pumped? If so, from where?

 

 

I understood that there are back pumps all the way from the River Avon to the summit.

 

The recent failure of one of the Caen Hill back pumps meant that there was not enough water being pumped up to the long pound and subsequently the Wooton Rivers pumps could not be used leading to the closure and subsequent restrictions of the locks either side of the summit.

 

 

[Jen-in-Wellies]

To get an idea of just how vital water supply was and how much trouble the canal engineers went, to have a look at this:

 

https://www.youtube.com/watch?v=c3JIvaQsuEk

 

In summary, the first canal between Birmingham and the coal fields of the Black Country had to rise 40' with six locks to clear a hill, then six locks down again. There was only room and water for a tiny reservoir to supply the summit, so they had to back pump with steam pumps. They then reduced the summit height by three locks each direction and 20' while the canal was still in use to halve the water usage. When the civil engineering experience had grown, they then dug an entire new canal alongside in a huge cutting with no locks at all.

 

Jen

Edited August 21, 2019 by Jen-in-Wellies

[MtB]

27 minutes ago, Jen-in-Wellies said:

They then reduced the summit height by three locks each direction and 20' while the canal was still in use to halve the water usage.

 

Point of order M'Lud...

 

How does that work then? I admit I haven't watched the video but once a lockful has been pumped up to the summit, surely a boat descending any number of locks takes just one lockful of water with them down all the locks, no matter how many or how few locks there are.

 

 

 

 

[Jen-in-Wellies]

4 minutes ago, Mike the Boilerman said:

 

Point of order M'Lud...

 

How does that work then? I admit I haven't watched the video but once a lockful has been pumped up to the summit, surely a boat descending any number of locks takes just one lockful of water with them down all the locks, no matter how many or how few locks there are.

 

 

 

 

Quite right. I'd not thought it through properly and typed too quick. The actual reason was so they could feed the summit from a bigger reservoir, via what is now the Engine Arm as well as by pumping.

 

Jen

Edited August 21, 2019 by Jen-in-Wellies

[MtB]

Thanks, I thought there might have been something fundamental I was misunderstanding!

 

 

[TheBiscuits]

12 minutes ago, Mike the Boilerman said:

 

Point of order M'Lud...

 

How does that work then? I admit I haven't watched the video but once a lockful has been pumped up to the summit, surely a boat descending any number of locks takes just one lockful of water with them down all the locks, no matter how many or how few locks there are.

 

At least with narrow locks you don't need to get into the narrowboat vs widebeam water usage debate! 

[MtB]

2 minutes ago, TheBiscuits said:

 

At least with narrow locks you don't need to get into the narrowboat vs widebeam water usage debate! 

 

Yes but a short boat uses less than a long one......

 

?

[Flyboy]

If you go and see the Crofton beam engines in steam you will see that the water is pumped up from Wilton water and discharged via a leat into the top level. CaRT do something similar with an electric pump that sometimes breaks down so they get the beam engines going.

https://www.croftonbeamengines.org/

[doratheexplorer]

2 hours ago, Tony Brooks said:

 

 

Again look at the blue bits on the map. When you see lakes close to a canal they are almost certainly reservoirs built to feed the canal.  In this area of the GU they also pump water from underground sources.

 

If you look at the summit level of all (as far as I know) canals there will reservoir lakes around. Exceptions are the Welsh canal which is fed by the river Dee and the Shropshire Union that is fed by Wolverhampton sewerage works. Probably others as well.

Sometimes you even get to cruise around those lakes - eg Titford.

[Flyboy]

1 hour ago, Mike the Boilerman said:

 

Yes but a short boat uses less than a long one......

 

?

I think it is the other way round. A long boat displaces more water than a short one so uses less water.   ?

[MtB]

1 hour ago, Flyboy said:

I think it is the other way round. A long boat displaces more water than a short one so uses less water.   ?

 

I knew that.... ?

[magpie patrick]

It's well known that the country slopes east west as well as north south, so the K&A draws water out of the Thames and carries it all the way to Bristol, just like the Grand Union drains Birmingham into London...

 

4 hours ago, Tim Lewis said:

 

I understood that there are back pumps all the way from the River Avon to the summit.

 

 

Historically the only pumps were up into the 9 mile pound above Widcombe Locks in Bath, I assume that more water was needed for these than cane through Bradford. The original pump drew from within the bottom lock into the river, the canal company claimed as the water was in the lock it was their water, even though the lock was empty and the bottom gates were open. The courts sided with the mill owners and thus Claverton pump was built instead

 

4 hours ago, Tacet said:

How to fill and keep filled the summit level taxed the original canal builder.  The summit level could be no higher than could be supplied - hence tunnels and cuttings were used where needed.  

 

The preferred solution was to use or divert an existing stream.  Pumping water from lower levels was to be avoided due to complexity and expense   

The original plan on the K&A was a longer summit with a tunnel from Crofton to Wootton Rivers - then no pumps would have been needed. However the company took fright at the four long mile tunnel and opted for a higher summit and pumps...

1 hour ago, Flyboy said:

I think it is the other way round. A long boat displaces more water than a short one so uses less water.   ?

Taking this to it's logical conclusion, boats should be filled with water before using locks, so they displace more water... 

[Flyboy]

35 minutes ago, magpie patrick said:

Taking this to it's logical conclusion, boats should be filled with water before using locks, so they displace more water... 

Not logical at all I'm afraid. That would reduce the displacement. You would be adding the water that would have been displaced. ??

50 minutes ago, Mike the Boilerman said:

 

I knew that.... ?

I knew that you knew that.   ?

[Capt Ahab]

6 hours ago, Mike the Boilerman said:

 

Most people never think about it, and imagine the canals stay full of water by pure chance.

 

And think CRT's main function is to mow the grass and fix the lock gates. 

 

 

Dont forget about unblocking the Elsans.....

 

[doratheexplorer]

23 minutes ago, Capt Ahab said:

Dont forget about unblocking the Elsans.....

 

Are there any elsans left?