Droitwich canal, Culvert water levels

[max's son]

https://www.youtube.com/watch?v=d-vMDnpia3Y

 

This one shows the high street flooded and more water in the Salwarpe

[Mike Todd]

2 hours ago, magpie patrick said:

Just for clarity, the culvert carries the Body Brook under the M5 not the Salwarpe. Whilst clearly any rain over the catchment of the Salwarpe is likely to also fall on the Body Brook the Salwarpe levels are not, per se, an indicator of the level in the brook.

 

The lock down into the Salwarpe has a drop of about 4 feet. If water backs up the culvert from the Salwarpe then there is a far bigger problem than just the culvert! However, there is a pipe linking the canal above this lock to the canal in Vines park - this is in part a water supply measure to the barge canal and in part a flood prevention measure to ensure the Body Brook doesn't overfill an already swollen Salwarpe. 

It is six months since we were there but do I not recall that there is a weir in the Salwarpe alongside lock 7? And that the difference in the normal levels of both salwarpe and body brook is only around half if the lock fall?

 

I understood that the pipe was principally to avoid the two waters mixing? Or is that another canal myth?

[Captain Pegg]

35 minutes ago, Mike Todd said:

It is six months since we were there but do I not recall that there is a weir in the Salwarpe alongside lock 7? And that the difference in the normal levels of both salwarpe and body brook is only around half if the lock fall?

 

I understood that the pipe was principally to avoid the two waters mixing? Or is that another canal myth?

Your recollection that there is no weir on the Salwarpe alongside lock no 7 is correct. There is an overflow weir on the canal above lock no 7 that discharges into the Salwarpe and overall acts in the same way a bywash would any other lock. It also effectively carries excess water discharging into canal from the Body Brook into the Salwarpe.

 

I struggle to see how the difference in levels of the Salwarpe and the Body Brook can be anything other than equal to the fall of lock no 7 which is not a shallow lock, it’s normal fall is probably in the region of 8’.

 

The pipe is to segregate river and canal water. The inlet is also above lock no 7 on the towpath side and logically I would have thought is set slightly lower than the overflow weir into the Salwarpe. Segregation of water is also why the gates on Vines Park flood lock are normally closed when in normal conditions they could be left open.

 

JP

 

Edited September 30, 2019 by Captain Pegg

[Mike Todd]

18 hours ago, magpie patrick said:

Just for clarity, the culvert carries the Body Brook under the M5 not the Salwarpe. Whilst clearly any rain over the catchment of the Salwarpe is likely to also fall on the Body Brook the Salwarpe levels are not, per se, an indicator of the level in the brook.

 

The lock down into the Salwarpe has a drop of about 4 feet. If water backs up the culvert from the Salwarpe then there is a far bigger problem than just the culvert! However, there is a pipe linking the canal above this lock to the canal in Vines park - this is in part a water supply measure to the barge canal and in part a flood prevention measure to ensure the Body Brook doesn't overfill an already swollen Salwarpe. 

I think I was thinking of the Transition Weir at 52.2681028, -2.1371339.