Holland's high tech flood protection
High tech flood protection: how Dutch dikes are getting smart - via satellites and sensors.
Sure of defences
When roughly 25% of your country, home to some 60% of your population, lies below sea level, and 70% of your economic output is generated there, then there is talk of significant risk. Add to this the spectre of global warming and increasingly extreme weather and you have the pre-requisites for a perfect storm. There is zero tolerance for failure – Holland has to be sure of its defences.
Image: Source: Rijkswaterstaat
The Dutch have been rising to this challenge continuously, since as far back as the 13th century, but maintaining the status quo, and dry feet, is a complex balancing-act between nature and hydraulic engineering, requiring constant monitoring, innovation and improvement. Without its complex network of dikes, flood basins and sea defences, Holland would be literally be up the creek without a paddle. Additionally, if the nationwide network of pumping stations failed, within a week the entire country would be under 1 metre (3 feet) of water. It’s not surprising, therefore, that the flood protection systems that guarantee the safety of the lowlands are becoming ever more sophisticated.
Prepared for threats
Bad weather in January 2012 tested the Dutch flood protection systems to their limits. Due to heavy rain and storm-force winds, water levels reached a 14-year high. Rainfall in December had been 152mm – twice the average amount and the ground was saturated. In the city of Groningen, water was lapping just 7cm below the windows of the city’s prestigious museum and 800 people were evacuated from villages nearby. The Dutch, however, are prepared for these sorts of threats and a panoply of preventive measures swung into action, such as inflatable dams, storm surge barriers and emergency flood basins.
However, these measures are all implemented when the conditions threaten to become critical and the subsequent stresses on the dikes can be considerable. The consequences of a collapse would be catastrophic. By using state-of the-art monitoring, which allows accurate advanced predictions, the Dutch are concentrating on ensuring that the dikes are capable of withstanding the loads and pressures that come with extreme conditions. So the dikes themselves are becoming ‘smart’. "We've been adapting for 1,000 years. That's nothing new. It's just that climate change is going faster than it was before," remarks Lennart Silvis, the operational manager of the public-private Netherlands Water Partnership.
With around 3,000km of outer sea-dikes and around 10,000km of inner, canal and river dykes (Holland has 6,000km of busy inland waterways), the task of monitoring is immense, therefore technology and remote sensing is being developed so as to enable precise measurements and accurate forecasts to be made.
The IJkdijk (evaluation dike) is an international test setup for new inspection and monitoring technologies for water barriers. The purpose of the IJkdijk is to look into whether these inspection and monitoring technologies can be used to improve the inspection of levees in order to gain a clearer understanding of their behaviour. At the IJkdijk facility, breach tests in test embankments are carried out on a regular basis, leading to new insights and understanding. The LiveDijk Eemshaven is making history by making the progress of innovation in and around flood defences more tangible: online data from sensors in the dikes is now available for real-time viewing online. The scientific aims for trying out such a 'smart-dike' system are two-fold: first, to develop multi-sensor networks and IT-tools for them, and to provide insights to Dutch hydraulic engineers as to exactly why and when such 'water-retaining structures' would start to fail - before the water has a chance to pour through.
Current flood protection is primarily concerned with strong dikes. But the greatest gain lies in making the total system smarter: the dike, the decision-maker, and the environment. The Flood Control 2015 program integrates these three aspects in advanced forecasting- and decision-supporting systems. "We would like to be two times faster and two times better in our decision making," states Piet Dircke, a program manager at engineering firm Arcadis and the chairman of the Flood Control 2015 initiative.
Monitoring from outer space
The Dutch are also monitoring things from outer space. Using the radar images from the European Earth observation satellites Envisat and ERS-2, the Directorate-General for Public Works and Water Management (Rijkswaterstaat) can monitor the external integrity of the dykes remotely, every day, with millimetre accuracy.
Commercial companies in the Netherlands are also getting involved. TenCate GeoDetect is the world’s first intelligent geotextile. This is a system that provides early warning of deformations in soil structures. TenCate GeoDetect consists of a geotextile that incorporates optical glass fibres, as well as special instrumentation equipment and software. The slightest settlements and changes in temperature and strain in for example embankments and dikes can thus be registered at an early stage. This makes it possible to take any necessary measures and to avoid breaches.
Image: Source: DHV
With increasing economical investments being made in flood prone areas, flood risk management is a hot topic in many deltas and low-lying areas around the world. When dikes or levees are built, a choice has to be made as to what water levels the dike will protect against. But when a high water level is imminent, decision-makers and crisis managers will need to know the real strength of the dikes to prevent both excessive risk to the population and unnecessary and expensive evacuation. Dutch water-management experts are currently providing expertise all over the world, from New Orleans, to St. Petersburg and Jakarta. One group are involved in a pilot for monitoring river dikes and flood barriers in the province of Quang Nam in Vietnam. This work has been taken on by a Dutch consortium of private companies and research institutes that incorporates Deltares, Nelen & Schuurmans, Hansje Brinker BV and Miramat. The knowledge that has been gained in the context of this project can be applied in range of other countries and could lead to some very beneficial spin-offs. The pilot lasted until 2013 and encompassed the design of dams and dikes.