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General information

Admin — Mon, 09 Nov 2026 14:43:41 +0000

Since the reclamation and drainage of Flevoland, the province has experienced land subsidence. This subsidence is caused by soil ripening, compaction and/or peat oxidation. Subsidence is expected to continue playing an important role in the future. One of the consequences of subsidence is a reduction in drainage depth, putting both agricultural and other land-use functions under pressure.

Since 2021, the Flevoland Land Subsidence Area-Based Process has been underway. Within this process, potential pilot projects and measures to address subsidence have already been explored. An overview of potential alternative revenue models has been compiled, model studies have been carried out to calculate the effects of lowering water levels on ground surface elevation, and possibilities are being explored for devaluing agricultural plots to enable the generation of solar energy on agricultural land.

From 2025 onwards, we have been working on the next step: testing the knowledge gained in practice. Together with stakeholders, we are seeking clarity on feasible and promising strategies and measures to address subsidence while simultaneously preventing agricultural land from becoming wetter.

Objectives of the area-based process

The overall Flevoland Land Subsidence Area-Based Process has two objectives:

To conduct an open and transparent process involving all relevant parties and stakeholders. Everyone participates in the process on an equal footing, and together we work towards achieving the substantive objectives.
To test knowledge in practice in order to gain practical insights into feasible and promising strategies for areas where, as a result of ongoing subsidence, shallower groundwater levels are expected to occur in the future if current policies remain unchanged.

It is therefore essential to establish an open dialogue with regional partners and ensure the availability of relevant factual information, including practical experience. In this way, we aim to develop broadly supported and applicable solutions that can also be implemented in practice.

By approaching the process in this way, we aim to jointly develop an integrated understanding of the issues. These insights will give agricultural entrepreneurs in Flevoland a better understanding of the strategic choices they can make for their businesses in relation to subsidence. In addition, they will provide public authorities with guidance for developing appropriate new long-term policies for addressing subsidence in Flevoland.

To achieve the objectives of the area-based process, the work plan has been divided into two components: collecting and analysing field data, and collecting, analysing and combining already available information. These two components will subsequently be brought together so that the results can be translated into appropriate long-term policies.

Field data

Field data are collected in cooperation with farmers and the water authority. The main focus is on identifying suitable solutions to increase drainage depth, thereby improving agricultural conditions. At the same time, the effects of these measures on the subsidence process are investigated.

Measures being implemented within the subsidence area include the reprofiling of field ditches, lowering the water levels in field ditches and implementing seasonal water level management.

To assess the effectiveness of these measures, monitoring wells, soil moisture sensors and surface water monitoring points are being installed. Over a total period of three years, data will be continuously collected and analysed to determine the effectiveness of the measures. This includes examining their effects on the water and soil system.

In addition, the effects of the measures are assessed in relation to their impact on subsidence, with a particular focus on the long-term effects. The financial feasibility of scaling up the pilot projects is also examined, as well as the implications of incorporating the proposed measures into long-term policies.

Existing information

Existing information and data are collected and analysed for various components of the project. This includes information on subsidence in the specific context of Flevoland, as well as the characteristics of the soil and water system that may influence the spatial suitability of different measures. For example, soil composition may make a particular location more susceptible to subsidence in the long term.

Another topic being investigated is current and future agricultural suitability. This is assessed on the basis of field observations and the collected data. A comparison is made between current and future agricultural suitability, both with and without the proposed measures. The uncertainties associated with these scenarios are also taken into account.

Expected results

At the end of this area-based process, we aim to establish a shared and broadly supported understanding of what works in the subsidence areas of Flevoland. This understanding will be supported by the results of three years of field measurements and the validation of the effectiveness of the measures. In addition, the findings will be evaluated with farmers who deal with the consequences of subsidence on a daily basis.

The ultimate aim is to develop concrete guidelines and practical strategies that can be used by both farmers and public authorities.

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Admin — Mon, 09 Nov 2026 14:16:32 +0000

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Impact on argiculture

Admin — Thu, 09 Jul 2026 14:03:23 +0000

Flevoland was created through the reclamation of parts of the former Zuiderzee during the twentieth century. The Noordoostpolder was officially drained in 1942, followed by Oostelijk Flevoland in 1957 and Zuidelijk Flevoland in 1968. On average, the province lies three to five metres below the Amsterdam Ordnance Datum (NAP) and is therefore entirely dependent on active water management.

Following reclamation, the soil consisted mainly of young, water-rich sediments with low bearing capacity. To make the subsoil suitable for agriculture, infrastructure and habitation, it had to gradually drain and consolidate. This process is known as soil ripening. During soil ripening, the physical properties of the soil change as a result of drainage, shrinkage, soil structure formation and consolidation. These processes are accompanied by land surface subsidence.

Even before the reclamation, it was known that the soil would subside following drainage as a result of soil ripening and compaction. To monitor this development, long-term measurements were carried out at approximately ninety locations throughout Flevoland. In Oostelijk Flevoland, the predicted and measured subsidence showed reasonably good agreement. In Zuidelijk Flevoland, however, the actual land surface subsidence proved to be considerably greater than expected. The amount of subsidence originally predicted to occur over a period of one hundred years had already been reached approximately 25 years after drainage.

This underestimation is mainly attributed to differences in the subsoil. In particular, the ripening behaviour of highly organic clay layers and the compaction of deeper soil layers proved to be greater than initially assumed. As a result, more land surface subsidence occurred than had been anticipated in the original forecasts.

To gain a better understanding of future developments, new subsidence maps for Flevoland were produced in 2011. According to these forecasts, the ground may still subside locally by several tens of centimetres between 2025 and 2050. In areas with soft, organic-rich subsoil, land surface subsidence of up to approximately 50 cm is expected during this period. The soil will continue to settle after 2050. Locally, a further approximately 35 cm of subsidence may occur over the following fifty years.

Groundwater management and subsidence

As a result of ongoing land surface subsidence, groundwater levels come relatively closer to the ground surface. This increases the likelihood of wet conditions, which can have adverse consequences for agriculture. A high groundwater level can lead to reduced trafficability of agricultural land, restrictions on crop growth and a decrease in agricultural yields.

To mitigate these problems, the groundwater level or surface water level can be lowered. However, such a measure also has side effects. A lower groundwater level increases the effective stress in the soil, causing clay and peat layers to undergo further compression. In addition, processes such as shrinkage, oxidation of organic matter and further soil ripening may be accelerated. In turn, these processes contribute to further land surface subsidence.

This creates a complex interaction between subsidence and water management. On the one hand, lowering water levels is sometimes necessary to maintain the functional use of the land, while on the other hand, the same measure can contribute to an acceleration of subsidence. Finding a sustainable balance between sufficient drainage and limiting subsidence therefore represents an important challenge for water managers and policymakers in Flevoland.

Determining the effect of groundwater levels on subsidence

To make well-informed decisions regarding water level management, insight into the relationship between groundwater levels and subsidence is required. It is important to understand how changes in groundwater levels affect the various subsidence processes, such as consolidation, shrinkage, oxidation and soil ripening.

However, this relationship is not easy to describe. The sensitivity of the soil to changes in groundwater levels varies from location to location and depends on factors such as soil composition, organic matter content, the thickness of compressible layers and the historical development of the area. Furthermore, subsidence processes do not always respond immediately to changes in groundwater levels. Some processes may continue for many years.

Predicting the effects of water level adjustments therefore requires a combination of measurements, data analysis and model calculations.

Measuring and modelling subsidence

Subsidence is a phenomenon that develops over longer periods of time. In the short term, the term ground movement is generally used. Due to the complex interaction between different processes, it is only possible to determine over time whether an observed movement actually results in subsidence.

Long-term measurement series are therefore of great importance, as many subsidence processes extend over several decades. When such long-term measurement series are unavailable, the use of models can provide a good alternative for predicting future subsidence.

Models can be used to quantify the relationship between groundwater levels and subsidence and to estimate future developments. These models combine information about soil composition, groundwater levels and physical processes such as consolidation, ripening, shrinkage and oxidation. By calculating different scenarios, the consequences of measures such as raising or lowering water levels can be investigated. This enables water managers to better assess the effects of an intervention on both agricultural conditions and future subsidence.

For Flevoland, such models are of great importance. They can contribute to the development of sustainable water level management, in which the interests of agriculture, water safety and soil conservation are balanced as effectively as possible.

Links/References

Subsidence

Admin — Thu, 09 Jul 2026 13:34:27 +0000

What is land subsidence?

Land subsidence is the lowering of the land surface relative to a fixed reference point, such as the Amsterdam Ordnance Datum (NAP). The ground is subsiding in large parts of the world, including the Netherlands. This is caused by deformation of the subsurface at different depths.

Natural processes, such as tectonic movements and isostasy, play a role in the deep subsurface. In addition, human activities, such as the extraction of gas, salt or groundwater, can contribute to land subsidence.

In areas where the subsurface consists of peat, clay or other compressible sediments, land subsidence occurs mainly due to the compaction of these soft layers. As a result, the volume of the soil decreases, causing the land surface to lower.

Processes that cause land subsidence

Compaction of the upper soil can result from various natural and human processes. Compaction is the compression of soil layers under the influence of a load or a change in pore water pressure in the soil. Compaction can occur due to

loading of the subsurface by buildings, infrastructure or raised ground levels;
lowering of the groundwater level;
groundwater extraction.

When the groundwater level drops, the pore pressure in the soil decreases and the effective stress increases. As a result, soil particles are pressed closer together, leading to settlement and land subsidence.

In peat soils, a lower groundwater level allows oxygen to penetrate deeper into the soil. This accelerates the decomposition of organic material by microorganisms. This process, also known as peat oxidation, results in a loss of soil volume and consequently in a lowering of the land surface.

Shrinkage occurs when clay or peat soils dry out. Evaporation and drainage reduce the moisture content, causing the soil to contract. This process can be temporary or permanent and contributes to land subsidence.

Ripening is the process by which young, water-rich sediments gradually change after drainage from a soft, wet soil into a soil with a firmer structure. During this process, drainage, shrinkage and structural development occur, accompanied by a lowering of the land surface. Ripening can be accelerated by the presence of suitable vegetation, such as reeds.

In addition to processes in the shallow subsurface, processes in deeper soil layers can also contribute to land subsidence. Examples include tectonic movements, glacio-isostatic adjustments and mineral extraction.

Natural rates of land subsidence are generally a few millimetres per year. In densely populated coastal and delta regions, such as the Netherlands, these processes are often accelerated by human activities, including groundwater extraction, water level lowering, mineral extraction and loading of the subsurface. As a result, local subsidence rates of several centimetres per year can occur (Stouthamer & Van Asselen, 2015).

Consequences of land subsidence

The consequences of land subsidence vary by area and depend on land use, soil composition and water management. Important consequences of land subsidence include:

an increased risk of waterlogging and flooding;
higher costs for pumping and water management;
damage to buildings, foundations, roads, railway lines and pipelines;
an increasing risk of salinisation due to upward seepage of saline groundwater;
a decrease in agricultural productivity;
loss of soil carbon and greenhouse gas emissions, particularly in peatland areas;
increasing infrastructure management and maintenance costs.

Project

Admin — Fri, 22 May 2026 12:57:27 +0000