Layer 2: Impact reduction through spatial planning

Waterlogging and flooding cannot always be prevented. Therefore, the Netherlands is taking spatial planning measures to minimise the impact of waterlogging and flooding. For example, the impact can be reduced by using the soil as a sponge or by building houses on poles or terps. This page outlines how we can reduce the consequences of waterlogging or flooding.

The measures implemented in layer 2 are also intended to minimise societal disruption. That is why this layer is sometimes referred to as the preparatory “cold phase” to layer 3: Crisis control.

Using the Spatial Assessment Framework to select locations for new developments

The Spatial Assessment Framework for climate-adaptive built environments helps to give water and soil a directive role in spatial developments. The assessment framework features a decision tree, which indicates the flood depths and flood probabilities which make construction unadvisable.

Using the national benchmark for planned new developments

Are you planning new developments or designing an area? The National Benchmark for climate-adaptive built environments will help you to do so in a truly climate-adaptive manner. For example, are you committed to sustainable soil management, in both urban and agricultural areas? The Benchmark will help you improve the sponge effect. Furthermore, it will help to prevent unnecessary soil coverage, in order to improve rainwater infiltration. In existing built areas and new development locations, a key measure to increase the sponge effect is greening public space and gardens. At the same time, this opens up many opportunities for enhancing a city’s liveability.

Using the soil as a sponge to minimise impact

Using the soil as a sponge not only helps to prevent waterlogging, but it also reduces the impact of high water in combination with extreme precipitation. For example, in its study into the July 2021 flooding in Limburg, Deltares research agency identified the soil sponge effect as one of the measures to mitigate the consequences.

Database of measures

In some cases, waterlogging can cause damage. Water can flow across building thresholds and enter houses via basements; it can flood tunnels and cause manhole covers to float away. Some damage can be prevented relatively easily. A threshold can suffice to block water or divert it in another direction. Would you like to know what other measures you can take in layer 2? Consult the database Measures for flood impact reduction, which shows which measures you can take at various water depths and provides more information with each measure.

Setting down standards and responsibilities for vital and vulnerable functions

Extreme precipitation volumes for a prolonged period of time, such as occurred in the Dutch province of Limburg in July 2021, may result in damage to or failure of vital and vulnerable functions. For that reason, one recommendation of the Waterlogging and Flood Policy Platform was to set down standards and record roles and responsibilities in order to minimise the impact of damage to or failure of vital and vulnerable functions as a result of waterlogging. See also the knowledge overview and the discussion document on this topic.

How can the impact be reduced in rural areas?

The options for reducing the impact of extreme waterlogging in rural areas differ from those available in urban areas. In rural areas, the impact is greatest during prolonged periods of heavy rain. Together with municipalities and farmers, district water boards and provinces can take various measures to adapt an area to more extreme precipitation. For example, water storage can be created in rural areas by saturating farmland and by opting for wet crops. Another option is converting farmland into nature or water storage areas. The Deltafact on Trees, Forests and Water Management from the Foundation for Applied Water Research (STOWA) explains how natural forests, food forests and agricultural forestry in river catchment areas can foster water storage.

How can excessive groundwater levels be reduced?

Several architectural solutions are available to combat groundwater issues. For example, a basement can be waterproofed, thus preventing groundwater from entering the basement or crawl space. Groundwater levels can be lowered through drainage. The InfoMil Knowledge Centre website features more information on groundwater and on the responsibilities of municipalities, district water board and residents. The Bodem+ website features best practices and practical know-how that can help to include groundwater in municipal framework visions.