Canal and River Trust Drought FAC

[billS]

This has been pointed out to me on the Drought FAQ section of their website:

 

Why don’t you operate pounds brimming with water as the longer pounds could operate as a reservoir?

The loss of water from a canal pound due to leakage and seepage is the largest component of water demand on a canal system. Loss rates are at their highest during the summer, when soil is dry and water tables are low. The leakiest part of the canal lining is the top 15 cm (6 inches), because it is continually wetted and dried. It is also subject to holes or cracks formed by burrowing animals and wave action from boat propellers. So by increasing the operational level of a pound, especially in a drought, would greatly increase loss rates. During a drought, we actually aim to run pounds as low as operationally possible to reduce losses.

 

 

I am struggling with the logic here. The top 6 inches leaks  because it is continually wetted and dried, so we will create a new top 6 inches lower down  (which will be continuously wetted and dried and therefore develop leaks)?

 

[Señor Chris]

Meanwhile the water level in the Ripon Canal has been raised due to the dry weather.

 

[KevMc]

47 minutes ago, billS said:

This has been pointed out to me on the Drought FAQ section of their website:

 

Why don’t you operate pounds brimming with water as the longer pounds could operate as a reservoir?

The loss of water from a canal pound due to leakage and seepage is the largest component of water demand on a canal system. Loss rates are at their highest during the summer, when soil is dry and water tables are low. The leakiest part of the canal lining is the top 15 cm (6 inches), because it is continually wetted and dried. It is also subject to holes or cracks formed by burrowing animals and wave action from boat propellers. So by increasing the operational level of a pound, especially in a drought, would greatly increase loss rates. During a drought, we actually aim to run pounds as low as operationally possible to reduce losses.

 

 

I am struggling with the logic here. The top 6 inches leaks  because it is continually wetted and dried, so we will create a new top 6 inches lower down  (which will be continuously wetted and dried and therefore develop leaks)?

 

Maybe the lower level isn't as dried out as the higher level because the water has covered it during the winter ... and the water table assists in keeping it wet enough. But I'm no hydrologist

[Stilllearning]

55 minutes ago, billS said:

This has been pointed out to me on the Drought FAQ section of their website:

 

Why don’t you operate pounds brimming with water as the longer pounds could operate as a reservoir?

The loss of water from a canal pound due to leakage and seepage is the largest component of water demand on a canal system. Loss rates are at their highest during the summer, when soil is dry and water tables are low. The leakiest part of the canal lining is the top 15 cm (6 inches), because it is continually wetted and dried. It is also subject to holes or cracks formed by burrowing animals and wave action from boat propellers. So by increasing the operational level of a pound, especially in a drought, would greatly increase loss rates. During a drought, we actually aim to run pounds as low as operationally possible to reduce losses.

 

 

I am struggling with the logic here. The top 6 inches leaks  because it is continually wetted and dried, so we will create a new top 6 inches lower down  (which will be continuously wetted and dried and therefore develop leaks)?

 

Doesn’t it rather depend on where the pound is, geographically and geologically speaking? A pound on an embankment would tend to leak and dry out more than a pound in a valley, and a pound on chalk like the K&A, leaks more than a pound on granite like a pennine canal?

[magpie patrick]

As a long term solution lowering the water level doesn'twork for exactly that reason: in time the "top six inches" leak again. However as a short term solution to a drought there is no doubt it iscbetrer to keep that top six inches in the reservoir rather than the canal. Remember the reservoir also won't be full so it's not a waste of capacity to keep it there 

 

Another feature of a brim full canal is that water gets wasted when locks are not set ahead, as the lock above is emptied it runs over the bywash and isn't available to fill the next lock. 

[zenataomm]

Frequently Asked Cwestions

[Athy]

2 hours ago, zenataomm said:

Frequently Asked Cwestions

...or Conundrums?

[Jim Riley]

11 hours ago, Stilllearning said:

Doesn’t it rather depend on where the pound is, geographically and geologically speaking? A pound on an embankment would tend to leak and dry out more than a pound in a valley, and a pound on chalk like the K&A, leaks more than a pound on granite like a pennine canal?

Gritstone predominantly, no granite. 

[Stilllearning]

1 hour ago, Jim Riley said:

Gritstone predominantly, no granite. 

I knew I should have checked. Think my point about impermeability still stands though.

[Jim Riley]

6 hours ago, Stilllearning said:

I knew I should have checked. Think my point about impermeability still stands though.

No, there's  glacial ground up stuff mostly, above the bedrock, sand and pebbles and rocks. Bit leaky, still needs clay.