Articles & Case Studies

Remote Water Level Monitoring Eases Flood Worries at Wychavon

Posted: Monday 10th October 2011

A remote water monitoring solution from specialist consultants Hydro-Logic Ltd. helps Wychavon Local Authority Drainage Engineers ease flood worries for local residents.

The small market town of Evesham, with a population of approximately 22,000, in the Local Authority District of Wychavon in Worcestershire, is situated on a horse-shoe shaped strip of land, almost entirely surrounded by a curve of the River Avon between Stratford-on-Avon and Tewkesbury – a geographical feature which explains the town’s long history of flooding, which has been documented as far back as the 13th Century.

A little more recently, in May 1998, the river rose by 5.8m in a few hours – showing how rapidly water levels in the area react, and in July 2007, when the town suffered its heaviest rainfall in 200 years, the flooding was the worst in its recorded history. Not surprisingly, local residents have a heightened fear of a repeat performance every time heavy rains result in rising river levels.

One of the locations that suffered flooding in 2007 was a residential neighbourhood of the town, situated on Bengeworth Brook near to the point at which the brook is diverted into a culvert under a small shopping centre.

The responsibility for the Brook changes hands at this particular point, with the Local Authority being responsible for its course up to the culvert, including its passage through a small landscaped public park immediately before the stream passes under the building and into private ownership.

Over the years since the shopping centre had been built, residents had suffered several floods due to the screen on the culvert being blocked by trash and debris. In the early years this had been exacerbated due to the design and installation of the trash screen at too steep an angle, resulting in rapid blocking of the screen when the water level rose.

However, even the replacement of the original screen by a new one at a shallower angle did not entirely solve the problem, with trash and debris piling up against the screen fairly frequently, even when there had not been heavy rain, or indeed, when there was a very minimal risk of resultant floods. The heightened “flood awareness” of local residents meant that they were very quick to call Wychavon District Council to report blockages, resulting in frequent and unnecessary Engineering Team call-outs to check the screen.

The problem for Wychavon was therefore: how to effectively monitor the trash screen in order to be able to act quickly to avoid any danger of flooding, while at the same time avoiding unnecessary and expensive staff call-outs.

Tony Jones, Engineering Consultancy Manager, Wychavon District Council, explained, “The objective of this project was to find ways to help the residents in Wychavon avoid the problems of unexpected flooding and allay their fears. When we investigated several “near misses” we realised that the reason that flood warnings had not been received in advance was due to the fact that the warning alarms were on the main river, while the affected villages were situated before the river. This presented us with an information gap to fill and we were determined to install a system which we could interactively interrogate, in order to provide the best and most appropriate flood response services to our residents.“

It was clear that a technical solution would be required and the District Authority therefore sought the assistance of Herefordshire-based Hydro-Logic Ltd., an independent company which brings together specialist water monitoring consultancy services, as well as offering a range of monitoring products - and which was therefore able to offer a complete turnkey solution.

After detailed investigation of the problem Hydro-Logic designed, specified and installed a level monitoring and early warning system, which would deliver vital and timely notification of rising water levels by the culvert.

The completed installation uses a combination of Isodaq products and systems, including robust, field-based instrumentation, with a remotely controlled camera and a mini-weather monitoring station situated above the water level monitoring equipment. This field station sends data, including photographs, via the web to engineering staff either to their office computers or to their mobile phones or laptops.

The benefits of this system are significant, firstly the field-based components are simple to install, robust in operation (essential given the location), driven by solar panels, and require very little maintenance, secondly, the web-based display systems are very easy to understand and require very little training to use.

In the Bengeworth Brook installation three “trigger points levels” have been programmed into the monitoring system, and when each level is reached it automatically sends an alarm to a pre-selected list of recipients.

In addition, if the Drainage Engineers receive a phone call from a worried resident, they can remotely activate the camera and obtain an immediate photograph of the situation at the culvert, and from that information make the decision as to what action is required.

This installation has now been incorporated into a flood alert early warning system for the area in which six locations are considered to be at high risk of flooding. Some of these locations have only the Isodaq data logger and telemetry installed, as they currently have no need for the camera option, though it could be added later.

Andrew Fell, Wychavon’s Assistant Land Drainage Engineer, commented: “With this system, we can respond to residents’ concerns immediately, as a photograph can be produced whilst the resident is on the phone and a decision can be made quickly as to whether an inspection is required. This now means we do not have to make unnecessary site visits. A big plus of this system is that the residents’ fears have been reduced substantially.”

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