Tracking coastal erosion

UK collaboration develops system designed to gather and wirelessly transmit coastal erosion data from beneath the sea. Siobhan Wagner reports.

A new sensor communication system that directly transmits data from underwater sensors to shoreline bases claims to monitor more closely the effects climate change has on coastal erosion.

The technology is the result of an 18-month UK industry and academic collaboration.

Sensors on the seabed around the UK’s coastline would gather data such as temperature, pH levels and sediment movement. This information would be fed to an underwater radio modem that transmits the data wirelessly to an onshore radio modem connected to a PC.

The backbone of the technology comes from project partner Wireless Fibre Systems (WFS) a Scots developer of underwater electronic communications, sensing and navigation technology.

The company’s underwater radio modem uses a magnetic loop antenna capable of generating an electromagnetic field of under 9kHz. The data is encoded in the magnetic component detected by a second sensitive receiver loop.

The signal is enhanced with digital signal processing.

Ian Crowther, general manager of environmental and industrial division at WFS, said one of his company’s underwater broadband modems has been proven to transmit signals at speeds of 1mb/sec.

‘There is no content that is restricted,’ he said. ‘It can transmit voice, data or video.’

Crowther added that these signals penetrate both water and air and operate in both shallow and deep water. For monitoring coastal erosion, the sensors need to be up to 200m from shore.

The project has received about £450,000 from the Technology Strategy Board and will be managed by the School of Applied Computing at Swansea Metropolitan University. Valeport, a UK hydrometric and oceanographic instrumentation manufacturer, is the other partner in the initiative.

The collaboration hopes to develop a technology that will, for the first time, gather and wirelessly transmit data related to coastal erosion from beneath the sea in real-time.

‘It hasn’t been done before because there has been no technology available that can transmit data from beneath the sea back to shore — not wirelessly anyway,’ said Crowther.

Previous systems could only relay data back using either a buoy on the ocean surface or a cable running from the underwater installation to the shore.

Crowther added: ‘No-one has been very successful at getting two-way communications, but by applying novel digital signal processing techniques and new antenna designs to existing science we have been able to increase the data rate and establish two-way communications with our system.’

The information gathered will support decision-making on coastline management around the world. Coastal erosion is caused by the impact of waves and small particles of rock and sediment wearing away the land.

According to recent research at London’s International Institute for Environment and Development, one person in 10 worldwide lives less than 10m above sea-level and near the coast. Current scientific data suggests that climate change will continue to cause rising sea levels and speed up beach erosion. Crowther and his colleagues believe potentially disastrous situations could be avoided with better monitoring of what is happening below the sea.

He said much of today’s information about coastal erosion is gathered from aerial photographs.

‘With our underwater system you will be able to understand things such as sediment movement from the sea bed which you can’t get from aerial photography,’ he said.

WFS has recently won contracts to use its technology in the defence and offshore oil and gas industries.