Dutch soil sinks more than expected
We already suspected that the ground in the Netherlands was subsiding, but it has now been measured for the entire country for the first time. The ground is subsiding much more than expected, especially in the west. This is evident from data on the new Dutch Ground Subsidence Map, which is being presented this week by the Netherlands Centre for Geodesy and Geo-Information (NCG) on Tuesday, November 20 during Geobuzz in Den Bosch, and on Thursday, November 22 during Veenomeen in Zaandam.
Interactive map
A team of researchers led by Prof. Ramon Hanssen (NCG / TU Delft) has processed three different types of measurement data into the underlying model: satellite radar, GPS, and gravity measurements. This data has been processed into an interactive map on a publicly accessible website: bodemdalingskaart.nl. Because the map shows the location of oil or gas fields in addition to the different soil types in the Netherlands, the cause of the observed land subsidence is clearly visible. The map is kept up-to-date with new satellite measurements that become available daily. This makes it possible, for example, to track whether land subsidence is decreasing with reduced gas extraction in Groningen.
Shallow land subsidence
With the map, researchers have been able to distinguish for the first time between the deep causes of land subsidence, such as gas extraction, and the effects in the top few meters. Until now, the latter could not be measured directly. It turns out that this 'shallow' land subsidence is even greater in various places in the Netherlands than that caused by the known, deep causes. Particularly in the peat and clay areas in the west of the country, this land subsidence is now clearly measurable, and was noticeable last summer, with dozens of houses showing cracks and sinkholes due to the drought. Climate change appears to play a major role in this accelerated land subsidence. Due to the relatively warm summers, peat soils dry out more, resulting in faster land subsidence. This is an irreversible process: the peat oxidizes, which also releases more CO2 into the atmosphere.
According to Hanssen, the picture emerging from the map clearly indicates the severity of the problem of land subsidence in the Netherlands: 'If land subsidence continues at the current rate, it could well mean the end of the characteristic Dutch landscape with meadows, cows, and windmills, or enormous damage to historic city centers.' Damage that, according to the Netherlands Environmental Assessment Agency, could amount to 22 billion euros by 2050.
However, the ability to measure this accurately now is good news. Water boards can use these measurements to manage their water levels more effectively, for example by better anticipating periods of drought.
About the Land Subsidence Map
The bodemdalingskaart.nl project is an initiative of the Netherlands Centre for Geodesy and Geo-Information (NCG), the same organization that initiated the NAP measurements of the Netherlands, designed the first continuous GPS network in the Netherlands, and was instrumental in the creation of the current elevation model of the Netherlands (AHN). Various universities, knowledge institutes, and companies, including SkyGeo, have contributed to the result. SkyGeo is an expert in radar analytics and the monitoring of infrastructure and soil.
Breakthrough through collaboration between SkyGeo and TU Delft
The improvement of satellite radar analyses, which made shallow land subsidence visible with millimeter accuracy, was made possible primarily by the processing and integration of the satellite data into the scalable SkyGeo platform. The billions of measurements were partly generated from Sentinel-1 SAR images from the European Space Agency (ESA). SkyGeo has built countless innovative algorithms on top of these images. SkyGeo was the first to invest heavily in the data center and the technological breakthroughs that are now front-page news. As of today, the land subsidence data is available to all users in the Netherlands.
High-resolution radar images
The radar images used for bodemdalingskaart.nl have a low resolution; moreover, the data are only available per grid cell to make them suitable for global insights. In addition to the free low-resolution data, SkyGeo also offers high-resolution data that maps subsidence in much greater detail – at the scale of individual bridges, roads, and buildings.
