Press release

'Critical asset’ for predicting flooding in York being built

A concrete channel that will help predict whether York is likely to be affected by flooding is being constructed in the River Nidd by the Environment Agency.

The concrete channel being built under the A59 at Skipbridge which will help measure flow rates

The concrete channel being built under the A59 at Skipbridge which will help measure flow rates

Anyone who frequently travels on the A59 between York and Harrogate is likely to have noticed a construction site at Skipbridge, Green Hammerton.

Taking place under the bridge, the Environment Agency is building a new channel to enable river flow meter readings to be taken.

Project manager Oliver Wilson said:

This is one of the Environment Agency’s critical assets for our flood warning service and for managing water resource available for abstraction.

Having an early warning that the Ouse could overtop in York means we can act early to prevent flooding by closing flood gates in the city.

The project involves building a concrete lined channel under the width of the River Nidd.

But building structures in a river channel is no easy feat, so a cofferdam has been built.

One half of the river is dammed off to create a dry working area to enable construction on that side, before the other side is dammed and the new channel structure can be completed.

The construction under the river enables an ultrasonic device attached under the bridge to measure the exact flow of water coming down the Nidd, which joins the Ouse about a mile downstream at Nun Monkton.

There was an existing concrete channel built a number of years ago but due to the design and flow dynamics it created in the river the bed got silted up, causing incorrect flow readings and it not working as an effective gauge station.

The new channel is designed to make sure sediment passes through it and flow readings are accurate.

Mr Wilson added:

Lower river levels have enabled us to make really good progress and we expect the gauge station to be fully functioning this winter.

North Yorkshire County Council’s Highways Department has carried out work on the bridge and road earlier this year and Northern Powergrid also recently installed an electricity line across the bridge.

Published 5 July 2018