Where houses should be built, are deep polders suitable for this as well?

And that ? Because at the same time, everyone can feel that there is a limit somewhere. If we keep building in the lowest and most vulnerable places in this country with rising sea levels and declining soils, it must go wrong at some point, right?

What perspective do we take?

The difference lies in the level of scale and the period with which we look at the effects of these projects. In Dutch regional development, there is a strong emphasis on the local perspective. Driven by the severe housing shortage, our intelligence and innovative strength help us make everything possible everywhere. There is no such weak soil, no such high water table, no such salty polder, unless we have a solution to living there in a dry and climate resistant way.

But long-term large-scale developments in land subsidence and sea level rise increasingly require a systemic and long-term perspective. What is sustainable locally and in the short term can backfire at the system level and in the long term. From this perspective, it is therefore important to add two compromises.

1. Reserve space for the future

In our white paper “A place for the future” we have shown that by 2050 around 900 billion euros will be invested in housing, infrastructure, energy transition, climate resilience and nature. These investments require more than 100,000 ha of space and thus largely determine what the Netherlands will look like after 2050. At the same time, in the lower regions of the Netherlands, measures will be needed in the future to to absorb increases in water level (such as flood zones, widening of dikes, etc.) and to adapt infrastructure and buildings on or along the water. In order to maintain sufficient space for these measures and to prevent them from becoming unaffordable due to complex integration, it is important not to accumulate all the available space. It is also important not to build in the deepest places so that they remain available to temporarily store excess water in the future. The key word here is flexibility. By reserving space now, we are keeping options open for future measurements.

2. Respect the limits of the soil and the water system

Secondly, it is important that in the development of the area we again learn to respect the limits of the soil and the water system. In many places in the Netherlands the potential uses of the land and the water system are ‘exhausted’. Draining deep polders means the higher area dries up and we need more and more fresh water to keep salinization running at bay. This cannot last indefinitely, especially as these effects are accentuated by climate change and subsidence, and fresh water is also becoming scarce.

In principle, urban development offers an excellent opportunity to reverse these negative trends in deep polders. Urban areas require less drainage, are less dependent on fresh water than agriculture, and offer opportunities for additional water storage. Achieving this ambition requires (generally) raising (ground) water levels. However, in practice, we often find that this ambition is not or only partially achieved. What starts with big ambitions for floating living or crawl-less construction often ends with traditional methods because we do not accept the additional costs for the construction method or construction preparation, or because the existing functions interfere. With all its consequences. It is therefore important that we henceforth prevent system-level effects taking into account as hard principles that long-term developments should not lead to a drop in the level of (groundwater) water, and should help to reduce or stop the water level. subsidence, salinization and / or dependence on water supply.

Scale effect

For both considerations, the effect of a single neighborhood on the system is generally small. But due to the magnitude of the housing task, the sum of the effects is unacceptably large. It’s like eating a sack of licorice. You can reason separately for each drop that it doesn’t make you fat, but after eating the whole bag, that reasoning always fails. We will have to seek a “stand-still” principle in which the sum of the developments does not demand more from the soil and water system than it provides in its natural form. In fact, we must use the 900 billion euros of investment in the coming decades and our innovative power to reverse these trends and become more resilient to climate change than we are today.

Discussion

These two system-level considerations are not yet secured in our regional planning policy. These effects are also not adequately addressed in the master plan and the memorandum on the scope and level of detail of the new Zuidplaspolder village. This place is not the only one. It is our collective blind white. This raises the question of who is responsible for the system.

The basic principles could be given a good place to prevent long term effects of the system by rehabilitating the water test. But we are not there yet. The consequences can be considerable as they require a real transition to the principle of “function follows level”. This means that we really can’t build everywhere anymore because we have to reserve space for the future. Or that we have to incur additional costs so as not to exhaust the possibilities offered by the soil and water system. It requires regional level agreements on what is allowed and what is not, a discussion of where borders are located and how we adapt our land use to them. Wanting to take these effects into account again clearly shows that a direction is needed at the system level and in the long term. Without direction, we eat empty sacks full of licorice and later we desperately wonder how it came to be that we got too fat.

Alex Hekman, Commercial Director

Email: [email protected]