Assumptions & limitations for subsidence
When using the land subsidence datasets, it is important to combine them with local knowledge, additional data, and further research. In addition, each dataset has specific assumptions and limitations that should be considered.
The dataset on recent land subsidence shows movement of the ground surface only, not of buildings or infrastructure. It should not be used at the individual plot level or to draw conclusions about liability. More detailed information can be found in the technical documentation (PDF).
When assessing the datasets on future land subsidence and the loading-related subsidence the following assumptions and limitations should be considered:
- The data is based on the Royal Netherlands Meteorological Institute’s (KNMI) 2014 climate scenarios rather than the 2023 scenarios and use spatial output from the Atlantis land subsidence model, whose underlying assumptions should be reviewed carefully.
- The high climate scenario assumes continued water level indexation, while the low scenario assumes large-scale fixation of surface water levels. The latter is a highly unlikely outcome, included mainly to illustrate how human intervention can reduce subsidence.
- Peat degradation, consolidation, and creep are included in the calculations, but shrinkage and swelling of clay are not, due to their short-term and unpredictable nature. Gas and salt extraction are factored in, with predictions adjusted to reflect the recent phase-out of extraction from the Groningen gas field. However, potential interactions between deeper and shallower subsidence sources are not accounted for.
- Regionally, lower-resolution input data means the maps are less accurate, and figures from a previous dataset version have been adapted for use here. Additionally, some linear features on the maps show subsidence estimates that are less reliable and likely overestimated, mainly because groundwater levels at these locations are poorly represented in the underlying models.
- More detailed information can be found in the technical documentation (PDF).
These datasets on pile rot risk and differential settlement also rely on the KNMI 2014 climate scenarios, and are based on national models and assumptions, meaning they are far from complete or fully accurate. Several damage mechanisms are not included and little is currently known about how shrinkage-swelling behaviour affects shallow foundations. As a result, some neighbourhoods may face risks not reflected on the maps, or vice versa. Previously completed mitigation or repair work is also not captured, as this information is not available nationally. Foundation type assumptions are based on general location, building age, and soil type (peat/clay), buildings on sandy subsoil are assumed to have shallow foundations unaffected by settlement. Because of these limitations, the maps should not be used to draw conclusions about risk for individual buildings or blocks; this requires local data. More detailed information can be found in the technical documentation (PDF).
