A flood watershed

Remote control and monitoring is the future for flood prevention in low-lying areas, explains E&T.

Around five million people live in flood risk areas in England and Wales, according to the Environment Agency. Some parts of the UK are even below sea level, leaving them constantly at risk from permanent flooding and water logging.

However, the flood risk can be reduced by drainage districts, which have been set up to prevent flooding by providing flood protection and water-level management schemes, which involves improving and maintaining rivers, drainage channels and pumping stations to evacuate water.

Despite the problems with flooding in the UK in recent years, the South Holland district of Lincolnshire - so named because it is an area of low-lying land akin to the Netherlands - has not been adversely affected. The South Holland Internal Drainage Board (SHIDB) is responsible for the drainage of the 38,441 hectares of valuable fertile land sandwiched between the rivers Welland and Nene, which includes 16 pumping stations and seven tidal-controlled gravity sluices connected to a network of 704km of drainage channels.

When the SHIDB wanted to monitor these sites remotely it installed a system that would not only monitor but also control 16 unmanned remote pumping stations from an office in Holbeach.

Sarian DR6410 routers

Phase one of the deployment, which was completed in November 2008, saw Sarian DR6410 routers being used for both fixed line and mobile communications. BT broadband connections were used wherever possible, but mobile networks in the form of dual Vodafone and T-Mobile SIM cards are being used in some of the more remote locations to provide a backup in the event of router downtime.

Industrial wireless access points (APs) are also present at selected sites to ensure that engineers can still access the pumping stations in the event of bad weather. Each pumping station has automatic controls - telemetry - capability for central monitoring and an alarm system detecting fixed-line failure.

With Sarian's routers transmitting data every 10-15 seconds, it not only enables SHIDB to monitor the district's water levels and status of each site's equipment in real-time, but also permits the engineers to switch pumps on and off remotely, as well as to adjust the target water levels and pump sequences. This means a site can be scanned and assessed from the office before a decision is made over whether to dispatch a team to deal with any issues.

The telemetry system is configured with a secure virtual private network (VPN) tunnel back to the master router from each remote location. Some sites are also equipped with IP cameras, which feed images back to the office allowing real-time images of water levels, as well as acting as a valuable intruder detection system and safety monitoring device when engineers need to remotely control pumps.

"CCTV gives SHIDB much needed visibility as well as control over South Holland's drainage network, permitting engineers to monitor each site without affecting manpower," says Stuart Gaunt, principal project engineer at Cougar Automation, who installed the system. 

Commenting on the system performance so far he says, "In the last 12 months since handover the system has been doing very well. The only issues have been the occasional communications failure due to the broadband links - the lack of 100 per cent reliability on the public Internet and particularly, the mobile links have been the only issues."

Private APN

When asked whether he would change anything Gaunt replies: "Not in principle, but we would probably make some minor changes. Obviously, the technology has moved on a bit since phase one. At that time there was no flat-rate system available on mobile tariffs. I was negotiating with Vodafone business units to try to get them to understand what our requirements were, but it took them a while to grasp it and they were beaten to the punch by T-Mobile."

He explains, "I was also talking to a company that provides a private APN system over mobile networks, However, that is very expensive, so we found that using Sarian routers and a standard flat-rate 'sim card only' tariff, we could establish reliable tunnels without the need for a private APN."

Phase two of the Sarian deployment was implemented as this issue of E&T went to press. "We are doing it now because the environment agency has got quite stringent requirements for continuous monitoring," he explains. Before the upgrade if there was a comms outage on a channel, the data was lost.

"So, what we are doing now is installing phase two of the project, which is a store and forward system. It was always anticipated and all the equipment was installed before, but not the software because of budgetary constraints. We are now upgrading the software, at both ends of the system, so that in the event of a communications link failure the local equipment and local plc starts data logging locally. As soon as the comms link comes back in again that data is forwarded on to the main database where it is integrated with the real-time data from other stations." 

This additional data allows SHIDB to record and archive water levels and pump run hours, as well as any action taken by the engineers. Hydrological modelling will allow SHIDB and other internal drainage boards, to compare and contrast rainfall in the district with the amount of water discharged from the catchment area, among other details.

"South Holland Internal Drains Board has now taken over about five other drainage boards locally and they are now part of an organisation called WLMA, which is the Water Level Management Alliance. So, we are hopeful that because of this project there will be further opportunities to deploy this sort of technology with the other areas."

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