Five million for pioneering research into land subsidence in the Netherlands

Published: 13 June 2019

The Netherlands Organisation for Scientific Research (NWO) announced today that funding amounting to €5 million will be granted to a consortium of research institutes for the purposes of the further investigation of land subsidence in the Netherlands. Deltares is part of the consortium led by Utrecht University. Ongoing subsidence on the surface and in the subsurface has major social and economic consequences. Different disciplines such as physical geography, satellite geodesy, biology, soil chemistry, environmental sciences, agro-economy, civil engineering, spatial management and legal studies are now teaming up to make the Netherlands future-resilient.

More than 500 million people live in river deltas around the world. These areas, where the subsurface is often soft, are being used ever more intensively and are becoming ever more densely populated. Groundwater extraction, heavy buildings and reductions in the water level for agriculture and cities are causing the consolidation of the ground, which in turn leads to damage to crops, buildings and infrastructure. Low groundwater levels due to the lowering of the water level, resulting in land subsidence, can also contribute to a warmer climate as dry peat releases greenhouse gases. A country that subsides as the sea level rises becomes increasingly difficult to keep dry. The effects of land subsidence are also clearly visible in the densely populated Dutch river delta. A sustainable delta requires a thorough approach.

Full scope

A large research team has now received 5 million euros to look at the full scope of this challenge and determine how the Netherlands can best deal with subsidence. Residents, companies, municipalities and water authorities will be provided with action perspectives. The overarching aim of the programme is to integrate studies of the fundamental causes with studies of policy decisions. Land subsidence has several causes that, in conjunction, explain the overall subsidence pattern. The final effect of all these causes varies from place to place, as does the best way to tackle the problem. The big question is how we can reverse our current approach to land subsidence if the damage becomes too great. The answer depends on breaking down the causes in the right way.

Building a firm knowledge base for the future

Deltares makes a considerable contribution to the supervision of scientific researchers, the use of laboratory facilities and model instruments. Gilles Erkens, land subsidence expert at Deltares and Utrecht University: ‘The approval of this wide-ranging research proposal on land subsidence means we are establishing a firm knowledge base, both in terms of people and in terms of excellent knowledge of this highly relevant area.’ That is needed to identify future-resilient solutions and make informed policy decisions. Deltares is also actively involved in two other major land-subsidence programmes: the Green Heart Land Subsidence regional deal and the measurements of land subsidence and greenhouse gas emissions on a national scale that are being presented as part of the national Klimaatenveloppe programme. The three programmes dovetail well and they ensure that the fundamental knowledge can be implemented in practice.

Researchers are coring to unravel the structure of the subsurface

From data to policy

‘To achieve all this, our first priority is to collect more precise data,’ explains Dr. Esther Stouthamer, a physical geographer at Utrecht University. ‘We are going to bring together these data from different sources, and then determine in several ways how fast land subsidence is in the Netherlands. By combining land-subsidence measurements from satellites with ground measurements in test fields and 3D maps showing the structure of the subsurface, we can use computer models for the entire country to analyse the causes of land subsidence. That is needed to isolate the exact causes for each location – natural and man-made – and to determine which combinations currently result in fast and long-term subsidence. Using the same computer models, we will also be predicting the extent of land subsidence in the future and the associated costs. We will be doing this for several future scenarios with and without changes in land use and water management. This will establish a basis for new policies and for new solutions to deal with this issue as a society.’

Transdisciplinary approach

The transdisciplinary approach in this research programme requires intensive collaboration between social partners and research institutes. The programme brings together Utrecht University, Delft University of Technology and Wageningen University & Research. They will address the fundamental knowledge base in the fields of satellite geodesy and civil engineering (Delft University of Technology), spatial cost-benefit analyses and soil chemistry (WUR) and physical geography, biology, spatial policy, and regulation and legislation (Utrecht University). Deltares, TNO and Wageningen Environmental Research will play an important role in the management of national data, advising government authorities, and the practical application of knowledge about land subsidence. Ministries, provincial and municipal authorities, and water authorities will be the social partners in the programme. Other stakeholders include the business community such as engineering and consultancy firms.

The problem of land subsidence is already high on the civil-service and executive agendas. A scientific research programme has now been added to that effort.