The top 20 municipalities in the Netherlands with the most variation in subsidence
Subsidence across the country: a comparison
Leaning houses, sinking streets, shifting dikes, and drying nature reserves. The new interactive subsidence map 2.0 provides insight into nationwide ground movements with an unprecedented level of detail, comprising more than a quarter billion measurement points over the past four years. Everyone can now explore the InSAR dataset, which can support insights into infrastructure across the entire country.
SkyGeo has processed images from the ESA radar satellite Sentinel-1 into time series of subsidence at hundreds of millions of measurement points, in accordance with Rijkswaterstaat specifications. The recently published Soil Subsidence Map 2.0 data make it possible to compare subsiding municipalities with each other in a highly quantitative and detailed manner without manual measurements.
Using this data from the subsidence map 2.0, we have a ranking of municipalities based on variation in subsidence. The first new insight from the ranking, created by SkyGeo, was a surprise. The top 20 municipalities with the most variations in subsidence in the Netherlands between 2015 and 2019 reveal a few unknown names.
Gouda topped the list of subsiding municipalities in our country during the latest policy-driven measurement. Parts of the beautiful historic city have been sinking by several centimeters per year for decades, causing the monumental quays to start overflowing even at high water levels.
Subsidence: various causes … and consequences
Each municipality has its own subsidence issues. Previously, measurements primarily drew attention to municipalities in the west of the country struggling with shallow compaction, such as Gouda. In this case, the upper peat-containing soil layer subsides, mainly due to lowering of the groundwater level. The relatively very warm, dry summers of recent years have certainly contributed to subsidence in municipalities on peat soil. What is subsiding in those municipalities are the streets and gardens, but not the houses. None of the municipalities in the top 20 will be surprised to be dealing with subsidence, but it is now easier to compare all municipalities objectively with one another.
The new leader of the ranking is dealing with a completely different set of issues. In Veendam, the high variations are primarily caused by the local subsidence basin above the deep-lying Veendam Salt Cushion. Such a subsidence basin is a lagging phenomenon that often occurs in areas where deep mining, salt extraction, or gas extraction takes place. Incidentally, Veendam is the only municipality from the North in the top 20. Furthermore, there are municipalities in South Limburg where the variations are actually caused by rising ground, with rising groundwater changes receding into the deep mines.
In short, at the national level, almost all regions are included. However, the municipalities in the Drechtsteden region and its immediate surroundings remain particularly strongly represented in the ranking. The municipalities of Diemen and Almere are the only representatives of the Greater Amsterdam region in the top ten.
Mapping the ranking of municipalities
The top 20 municipalities with the lowest stability index measured using data from subsidence map 2.0.
Veendam
Sliedrecht
Krimpen aan den IJssel
Gouda
Diemen
Schiedam
Hardinxveld-Giessendam
Barendrecht
Zwijndrecht
Papendrecht
Terschelling
Krimpenerwaard
Ridderkerk
Hendrik-Ido-Ambacht
Brunssum
Capelle aan den IJssel
Vlieland
Oldambt
Almere
Sittard-Geleen
All 355 municipalities in the Netherlands are dealing with moving soil; we have known this since Soil Subsidence Map 1.0. Local differences in soil subsidence can have significant consequences for the lifespan of gas and water pipes, roads, sewers, cables, and other infrastructure.
For policymakers in most municipalities, foundation problems caused by soil subsidence are a well-known issue that consumes a significant portion of the municipal budget. So now we can compare this.
Have you already optimized InSAR for your municipality?
If you want to start making policy decisions yourself using InSAR, we have the knowledge of how other municipalities approach this. Therefore, read our case studies on how satellite data is turned into real information for maintenance planning.
