APMR checks stability of dikes

A company from one of the European Space Agency’s Business Incubation Centres has developed a scanner to spot weaknesses in dike structures.

A company from one of the European Space Agency’s (ESA) Business Incubation Centres has developed a scanner to spot weaknesses in dike structures.

It is now being used to inspect dikes and dams on the River Danube and in the Netherlands.
Dutch start-up company Miramap’s instrument can ‘look’ into the ground and measure the amount of water in the soil, which is important when checking the stability of dams and dikes.

Very wet areas can indicate a weakened or even dangerously unstable structure.

By mounting the scanner on an aircraft, large areas can be mapped easily, identifying points to be inspected and perhaps repaired.

Miramap’s Airborne Passive Microwave Radiometry (APMR) soil-moisture instrument is based on passive microwave radiometry (PMR), a technology used on satellites to monitor changes in soil moisture and ocean salinity on Earth.

Roland Haarbrink, inventor of the instrument and director of Miramap, said: ‘We altered the space sensor for airborne operations to increase the spatial resolution from tens of kilometres to a few metres.

‘This increase of detail, combined with simultaneous data collection in different frequency bands and marking all measurements with satellite positioning data, makes it possible to track changes in soil moisture very precisely and to detect water seepage.

‘It is basically the same technology that ESA uses on its ‘SMOS’ water mission, operating in the L-band.

‘We have adapted the technology and improved it for land monitoring from an aircraft.’

Miramap completed the first flight campaigns with its APMR in 2006, covering dikes in the Netherlands in collaboration with the Dutch government.

Following the successful results, the scanner was used in a natural hazards and flood-management project for the River Danube in Bulgaria in 2007.

Today, it is used frequently in the Netherlands to monitor the country’s dike system.

Miramap’s technology was developed in ESA’s Business Incubation Centre in the Netherlands, part of the agency’s Technology Transfer Programme (TTP) office, set up to capitalise on space-based technology and know-how for the benefit of Europe’s economy and science.

Following two years of research and development of the new scanner, supported by ESA experts, the company won several contracts.

One was with the Dutch Ministry of Traffic and Water Management to monitor the moisture content of water barriers to detect dangerously weak zones. 

Soil moisture map of a Danube river section in dry conditions. The colours correspond to the soil-moisture gradations in the upper 0-5cm-thick layer.

  • Dark green – ranges between 0 and 0.05 m3/m3
  • Light green – ranges between 0.05 and 0.10 m3/m3
  • Light blue – ranges between 0.10 and 0.20 m3/m3
  • Dark blue – ranges between 0.20 and 0.35 m3/m3 and represents open water