The deepest Canal Summit

[Heartland]

Some historians have stated that a greater understanding of canal summits as a water supply deserves consideration. Putting aside the aspect of reservoirs and streams feeding the summit does a deeper summit level have value in its own right? 

 

For some waterways the length of the summit must be a limiting factor and so a related question is what was the longest summit level. When James Brindley's plan of a summit from Wolverhampton to Birmingham fell apart, the first solution was the short summit at 491ft od between Lock 6 and 7. That problem was solved later with the first reduction of the Summit that led to a waterway level from Smethwick to Wolverhampton as well as the canal through Dudley Tunnel at 453 ft that eventually extended to the Wallows via the private Pensnett Canal.

[BEngo]

I think the longest summit on a single canal is the Watford to Foxton pound.  Even though the Welford Arm climbs off that so THE summit of the Old Union  is at Welford, fed from reservoirs, a transit direct from the bottom of Watford to the bottom of Foxton is an up -and-down-again summit crossing .  The Coventry  and Ashby together are today a longer pound.

 

The long pound from Whilton Bottom to Stoke Bruerne, while not as long as Watford to Foxton , can also be a summit, for traffic up Stoke and down to Northampton.

 

The Worcester and Birmingham, The Stratford and the 473 ft level of the BCN are today  also a long summit, albeit there were stops at Kings Norton and Worcester Bar to break it into smaller lengths pre Nationalisation.

 

The Coventry Ashby Summit is curious too.   From the  Coventry Canal Company viewpoint it was a Summit  which stored  water for and fed the Atherstone flight and Glascote.  Very little water entered from the Oxford and there was a potential water  loss to the Ashby, if only through leakage and evaporation, so they wanted a stop at Marston Jabbets.  From the Ashby Canal viewpoint the Coventry was  a potential water predator, so the Ashby also wanted  a Stop at Marston.   From a waterway system view point you can lock down into the Cov. from the Oxford and the Coventry can be fed from the Oxford's reservoirs.

 

Using a summit as a reservoir is an OK idea, provided it is kept dredged to reservoir depths,  and has adequate catchment and capture so it will refill. To be effective, the top gate sills at either end need to be deep enough that an operating draught boat can still get into the locks when the summit is well low.

Edited December 19, 2022 by BEngo
Add BCN et al

[David Mack]

I've never been very convinced by the argument for a deeper summit as a reservoir. If the summit is built (and maintained) a foot deeper than the rest of the canal, then it can continue to operate with the level up to a foot down. Drain it down much deeper than that, and the loaded craft the canal was intended to convey will start to get stuck. The amount of water stored in a one foot depth of channel is pretty small compared to what a reservoir holds, so in reality it adds little resilience in times of drought.

[Jen-in-Wellies]

The summit pound of the Rochdale Canal struck me as being wide, compared with the rest of it. Doubling the width would have the same effect as doubling the depth. Also, making the pound as long as possible before the first lock each side would again store more water. 

 

8 minutes ago, David Mack said:

I've never been very convinced by the argument for a deeper summit as a reservoir. If the summit is built (and maintained) a foot deeper than the rest of the canal, then it can continue to operate with the level up to a foot down. Drain it down much deeper than that, and the loaded craft the canal was intended to convey will start to get stuck. The amount of water stored in a one foot depth of channel is pretty small compared to what a reservoir holds, so in reality it adds little resilience in times of drought.

The HNC summit, through the Standedge Tunnel would be a special instance of this. Not only would you want depth to prevent boats being stranded as the flights are used each side, but you would also want it to reduce resistance to boats moving through the narrow tunnel. Water can go underneath, when space to go round the sides is limited.

[dmr]

30 minutes ago, Jen-in-Wellies said:

The summit pound of the Rochdale Canal struck me as being wide, compared with the rest of it. Doubling the width would have the same effect as doubling the depth. Also, making the pound as long as possible before the first lock each side would again store more water. 

 

The HNC summit, through the Standedge Tunnel would be a special instance of this. Not only would you want depth to prevent boats being stranded as the flights are used each side, but you would also want it to reduce resistance to boats moving through the narrow tunnel. Water can go underneath, when space to go round the sides is limited.

 

I read somewhere that the Rochdale summit is (or was) extra deep to act as a resevoir but I am not convined, and I don't think its significantly wider than other parts of the canal.  The lock top gates look no different to the other locks so if the level drops significantly then getting over the cill will be the mimiting factor, no real point in making the canal deeper than the lock cill?

[magpie patrick]

I've always felt the claim that summit levels are reservoirs was a bit dubious, but that doeesn't mean some aren't deeper as a summit level, especially a short one, won't have the same resilience as a pound further down as the option of running water down isn't so easy. A foot or two extra would allow a draw down by day that might recover overnight. To benefit from this though the summit pound would need dredging... so I wouldn't rely on it now! 

[Jen-in-Wellies]

2 hours ago, dmr said:

and I don't think its significantly wider than other parts of the canal. 

You're right. In my memory, it was wider, but piccies say no. This will sound weird when Christmas is over, but it looks very strange with digital snow falling across the picture. 😀

 

[dmr]

That snow is very irritating.

The summit is moderately remote wilderness,  at least on one side, but it was once much more industrial. There was once a big brickworks which is what I assume that quarry was for.

 

Also, another bit of history, did you know that a narrow guage railway was built across the summit to remove the silt during the restoration?

 

(this photo is copyright but I have posted a link to Flickr rather than a copy of the photo which I hope is ok).

 

 

 

 

[BEngo]

If one allows Scotland into the possibilities, how about the summit of the Caledonian Canal?  One section is  deep enough to have it's own monster (maybe).

N

[Tacet]

6 hours ago, Jen-in-Wellies said:

HNC summit, through the Standedge Tunnel would be a special instance of this. Not only would you want depth to prevent boats being stranded as the flights are used each side, but you would also want it to reduce resistance to boats moving through the narrow tunnel. Water can go underneath, when space to go round the sides is limited.

Increased depth through the tunnel would be ideal, for the reasons you mention.

 

But a tunnel is about the most difficult place to increase capacity.  I can't see the shareholders taking well to the additional cost.

[Waterway2go]

1 hour ago, BEngo said:

If one allows Scotland into the possibilities, how about the summit of the Caledonian Canal?  One section is  deep enough to have it's own monster (maybe).

N

Nice thought, although the Caledonian Canal summit is largely a natural Loch.   The Forth & Clyde Canal summit is 16 miles long plus the 4 mile Glasgow Branch making a 20 mile reservoir.  Although not originally planned as a water storage feature it has now been re-purposed as a flood water storage system.  The Glasgow Integrated Water Management Scheme allows the canal summit to be lowered by up to a maximum of 100mm. before heavy rain so that an enhanced land drainage system  can send large volumes of water into the canal quickly, thus opening up areas of land in the City that could not otherwise be developed.

 

Scottish Canals earn a tidy sum from the City Council each year as a result.  Mor information here:  https://waterprojectsonline.com/custom_case_study/smart-canal-2022/

Edited December 19, 2022 by Waterway2go
spelling

[Derek R.]

I would have thought that the area of water more than the depth would be the deciding factor in whether a canal length was an effective reservoir or not.

Fill a glass to near the brim, and pour in half a cup more of water, and the result in an overflow. Do the same to a large bowl  (a greater area) and the level is barely affected.

[magpie patrick]

11 hours ago, BEngo said:

If one allows Scotland into the possibilities, how about the summit of the Caledonian Canal?  One section is  deep enough to have it's own monster (maybe).

N

Unless Nessie has made his or her way through the five rise at Fort Augustus, the summit of the Caledonian remains monster-free!

[BEngo]

22 minutes ago, magpie patrick said:

Unless Nessie has made his or her way through the five rise at Fort Augustus, the summit of the Caledonian remains monster-free!

Where do you think Nessie goes for holidays and when there are too many monster hunters on Loch Ness?

 

N

[Tonka]

Isn't Tring Summit on the Grand Union the deepest. The cutting there is pretty deep.

[David Mack]

The Bridgewater Canal. The first cut is the deepest.

[magpie patrick]

46 minutes ago, David Mack said:

The Bridgewater Canal. The first cut is the deepest.

 

 

Edited December 20, 2022 by magpie patrick

[Heartland]

The Kennet and Avon also probably deserves some consideration

[BEngo]

3 hours ago, Tonka said:

Isn't Tring Summit on the Grand Union the deepest. The cutting there is pretty deep.

Tring canal cutting is not  as deep as it appears.  Rather than cart the spoil away or use it as fill for embankments  much was piled up on either side of the cut,   raising the land level either side of the canal.

 

The water depth can be pretty poor too, mainly because large parts of the cutting are not puddled and the water level is affected by the local water table.  Fine if the water table is high, but not so good if not.

 

N

[koukouvagia]

On 20/12/2022 at 12:34, BEngo said:

Tring canal cutting is not  as deep as it appears.  Rather than cart the spoil away or use it as fill for embankments  much was piled up on either side of the cut,   raising the land level either side of the canal.

 

The water depth can be pretty poor too, mainly because large parts of the cutting are not puddled and the water level is affected by the local water table.  Fine if the water table is high, but not so good if not.

 

N

Apparently in 2011 the water table fell below the level of the canal and water drained out from the canal into the surrounding land.  CRT was not able to fill the canal up from the underground wells because they had exceeded their annual water extraction licence.  I remember being asked by CRT if I would run our ex working boat along the summit to test the depth.

3 minutes ago, koukouvagia said:

 

 

Edited January 10, 2023 by koukouvagia

[Scholar Gypsy]

7 hours ago, koukouvagia said:

Apparently in 2011 the water table fell below the level of the canal and water drained out from the canal into the surrounding land.  CRT was not able to fill the canal up from the underground wells because they had exceeded their annual water extraction licence.  I remember being asked by CRT if I would run our ex working boat along the summit to test the depth.

 

And in 2012 as well - we were worried about being able to get to London for the Jubilee Pageant!