Q=2*W*H^1.5

When gazing at the river have you ever wondered how much water is flowing past you?

The Club’s website gives the link to the Environment Agency and the water levels at Loud’s Mill and the weir on the Stinsford side stream but how do those relate to the amount of water flowing in the river?

There are two weirs and the fish pass at Loud’s Mill. According to EA figures the main weir is 10.66 metres wide and the width of the mill stream weir is 1.52 metres. They are both Crump weirs, a type widely used throughout UK Rivers because they have a stable flow against head characteristic and their calibration does not change much with changing water flow.

A text book equation for the flow over a Crump weir in cubic metres per second is: Q=2*W*H^1.5, where W is the width of the weir in metres and H is the upstream head in metres above level of the crest. Assuming that the water level measurement for Loud’s Mill is the same as the head over the weir, the flow can be estimated.

Yesterday, when I took the photo, the level at the front of the weir was 0.16 metres, which in theory gives a flow of 1.364 cubic metres per second or 1.364 tonnes per second.

According to the EA the typical range of river levels at Loud’s Mill is between 0.08 and 0.40 metres. This represents a range of flows over the main weir from 0.482 to 5.394 cubic metres per second.

In the photo you can see the 1 in 5 gradient fall off at the back of the weir. What you cannot see is the 1 in 2 slope at the submerged front of the weir leading into the crest. It is these slopes that are characteristic of a Crump weir.

By the way, yesterday the grayling fishing was good but instead of a fishing report I thought that some members might be interested to know how much water was coming down the river.
Jim

Lous Mill, DFC

Micro Tag

Monitoring Loud’s Mill Fish Pass

Since the fish pass was finished at Loud’s Mill Gauging Weir the Environment Agency has been monitoring how well fish have been using it. One part of this work has involved the capture and tagging of brown trout from above the weir and stocking them below. This was done in mid March and we have since been monitoring these fish as they ascend the fish pass.

If you decide to take a fish home you may find a tag (see picture below) in the belly of the fish.

If you are able it would be most useful if the tag was returned to us, at the following address, along with the date and exact location of the fish’s capture. This will enable us to fully understand the fate of those fish we tagged as part of this study.

Andy Martin, Environment Agency, Rivers House, Sunrise Business Park, Blandford Forum, Dorset, DT11 8ST

April 17, 2009 by Filed under: Loud's Mill Fish Pass 

The grand opening

Today was the official opening of the Loud’s Mill fish pass, we all met at the Environment Agency’s depot in St. Georges Road.
From Dorchester Fishing Club 2009
Andy Martin (EA) started proceedings, then our very own Charles Dutton gave an overview of how the fish pass came to be, quickly followed by Paul Knight (Salmon & Trout Association), Tony Andrews (Atlantic Salmon Trust), Richard Slocock (Frome & Piddle Association) and Oliver Letwin MP opened the fish pass.
From Dorchester Fishing Club 2009

We all then walked to see the fish pass in action – a super day and congratulations (again) to all involved in this project – a good job well done….

From Dorchester Fishing Club 2009
From Dorchester Fishing Club 2009
From Dorchester Fishing Club 2009
January 9, 2009 by Filed under: Loud's Mill Fish Pass 

It’s Working!

Hi All,

I thought you would appreciate and enjoy these 2 video clips of fish to using the Loud’s Mill fish pass. Our consensus of opinion is that the first is a salmon and the second is a brown trout. Sizing the fish is difficult as it is all relative to the camera, but the wall edges you can see in the bottom corners of the picture are 300mm apart so the salmon is deffinetly bigger than that. I suspect the brown trout is more in the 200 – 300mm range.

Have a good weekend
Andy
Fisheries Technical Specialist

October 17, 2008 by Filed under: Loud's Mill Fish Pass 

Loud’s Mill fish pass

My first visit since the completion of the fish pass and very impressive it is too. Here is a short video clip of the pass and notice how slow the water is as it reaches the bottom – brilliant..

and I spotted this big brown in the shallows!
August 17, 2008 by Filed under: Loud's Mill Fish Pass 

It Flows!

Pictures of the fish pass flowing properly for the first time are attached and I’m really pleased with how it looks.

Dawnus will be pulling off site by the end of next week, having completed a superb piece of work.

Regards
Andy Martin
Fisheries Technical Specialist

August 12, 2008 by Filed under: Loud's Mill Fish Pass 

Loud’s Mill fish pass

Well the project is very much in its final stages with the majority of works having been completed. Dawnus have spent the week finishing off various pieces of work including, the fitting of the mesh flooring over the fish pass, installing the lighting box for the video equipment and fitting out the new kiosk. This has included having the power hooked up and turned on.

On Monday the divers will be back in to cut the sheet piles in front off the fish pass, with a temporary stop log being installed to keep the fish pass dry (for now). On Thursday the trash boom is being delivered and this should be installed by the end of the week. On Friday the divers will be back to install the GRP extension to bottom of the fish pass that will hold one of the PIT tag aerials. As long as this work all goes to plan the temporary stopped log is scheduled to be removed next Monday (11th) and the water will flow down the fish pass for the first time. If anyone would like to attend the site while this is happening then please contact me first.

Dawnus are then aiming to finish on-site and by completed by the 15th.

We (that is a colleague and myself) will be back on site with the supplier of the PIT tag equipment to install it at the beginning of September. In the meantime though we should have the video equipment up and running to see if any fish choose to use the pass in August.

I’ll send a final update when the water flows (so to speak).

Regards
Andy Martin
Fisheries Technical Specialist

August 2, 2008 by Filed under: Loud's Mill Fish Pass, River Work 

It’s There!!!

We now have a Larinier fish pass in place at Louds Mill… Congratulations to all that contributed to this, especially Charles Dutton and the Committee of the Frome, Piddle & West Dorset Fisheries Association

Report by
Andy Martin
Fisheries Technical Specialist
Environment Agency
July 24, 2008 by Filed under: Loud's Mill Fish Pass, River Work 

Louds Mill Fish Pass Construction

Up until the middle of the week the programme was running to schedule with the concreting of the walls complete and all the formwork removed.

Dawnus were then due to install the formwork for the concrete slope that the fish pass will sit on and pour the concrete. However the severe rainfall and associated high river levels have meant that access to the site for the last 2 days has been restricted to foot traffic (and this has been difficult), therefore this work has had to postponed until the river levels drop (expected to be next week, given current weather forecasts).

On Tuesday we went and inspected the fish pass at the fabricators in Melksham. The construction of the fish pass tray, baffles and the welding work is of excellent standard and we are satisfied with the quality of the work that they have produced. The attached pictures show the whole fish pass and a close up of the front baffles which are the most critical to its performance (yes, it is as big as it looks).


Report by
Andy Martin
Fisheries Technical Specialist
Environment Agency
July 12, 2008 by Filed under: Loud's Mill Fish Pass, River Work 

Louds Mill Fish Pass Construction

The concreting of the floor and walls of the fish pass slot is now complete (see attached pics), with the formwork for the walls being removed today. The work continues to progress as programmed.

Next week they will be installing the formwork and pouring the concrete for the slope that the top of the fish pass will end up sitting on.


Report by
Andy Martin
Fisheries Technical Specialist
Environment Agency
July 3, 2008 by Filed under: Loud's Mill Fish Pass, River Work 

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