The role of water authorities and the potential of floating construction
The region of Stichtse Rijnlanden has a rich 900-year history of water management. During this period, and especially in recent years, significant changes have taken place. While centuries ago, inhabitants mainly adapted to natural conditions, we have increasingly manipulated the landscape to suit our needs; water and soil had to conform to our requirements. However, due to climate change, we are now experiencing more frequent periods of extreme flooding and drought. To make our landscape resilient for the future, we need to once again adapt to the climate, as we did in the past. The water board can no longer guarantee future water supply and drainage without a change in our thinking, where water and soil should regain their influential role. This also necessitates a different role for the Hoogheemraadschap.
Water and soil as guiding principles
In recent years, we have observed a shift in the role and position of the water board within spatial planning. This change is also reflected in the new water management program for 2022-2027, known as "working upstream." This means that as a water board, we aim to be more proactive and involved in spatial planning issues from the beginning of the planning process. This way, we can introduce water and soil-influenced thinking from the start.
Furthermore, societal challenges are becoming increasingly multifaceted. Numerous synergies are possible, allowing us to think not only from a water perspective but also to explore multiple land use options. For example, this includes the energy transition and new business models for agriculture. This approach is crucial considering the scarcity of space. Therefore, as a water board, we see great potential in floating construction as one of the possible solutions. This includes elevated construction on stilts and mounds.
Potential of floating cities
One significant advantage of floating construction is the combination of housing with (peak) water storage. It allows for accommodating larger fluctuations in water levels, as the floating homes literally move with the water level. From the perspective of developers, waterfront living can also increase the value due to the unique experience it offers. Additionally, floating homes can be (temporarily) relocated, providing additional benefits.
As water managers, we work on strengthening existing dikes to reduce the risk of flooding. Given the increasing extremes, it is essential not only to consider the flood risk from primary dikes but also to address inland waterlogging caused by extreme rainfall. Floating construction provides a solution for both situations, particularly in lower-lying areas and regions prone to soil subsidence, such as the northern part of the Rijnenburg polder due to peat.
Furthermore, in the future, as a result of climate change, we will face increasing water shortages, particularly during summer months. The challenge is to create a water system that is as self-sufficient as possible, both during periods of extreme waterlogging and drought. Adequate freshwater supply and good water quality are important considerations in this regard.
In the Rijnenburg polder, the municipality of Utrecht aims to develop approximately 25,000 sustainable and accessible homes, including the construction of a light rail connection. In the northern part of Rijnenburg, space has been reserved for a combination of an energy landscape and water storage. This location serves as the basis for researching the development of the floating city with wetland nature. To achieve sufficient water depth for a floating city, part of the soil needs to be excavated, with a focus on achieving a closed soil balance. This requires a shift in thinking, which will be explored further in the next phase of this research.
Follow-up Research: From Business Case to Value Case
In the follow-up research, we will quantify the societal values that floating construction can bring. Traditional approaches to financial cost-benefit analysis often focus on short-term perspectives within the framework of land development. Additionally, substantial future climate damages can be avoided through floating construction, costs that would otherwise burden governments, property owners, and future generations. By combining functions, such as housing and water storage, we contribute to increasing the societal benefits, thereby enhancing feasibility. By incorporating these societal benefits into our decision-making process, even in the short term, we can create a climate-adaptive and future-proof floating living environment that is truly enjoyable. It is also essential to ensure sufficient water availability and good water quality during dry summer months. Therefore, we are applying this new approach of assessing broad well-being in the ongoing research on floating construction in Rijnenburg.
Climate change and societal developments are fundamentally altering water challenges. We must once again adapt to the climate, and floating construction is indispensable for the Netherlands. This way, future generations can continue to live, reside, and work in our country, even with a changing and increasingly unpredictable climate. We strive for a safe environment with an abundant supply of clean water.
Regarding the case studies, they are focused on exploring the general potential of floating construction. The developed visuals and textual explanations are intended to inspire and stimulate thinking about compelling perspectives for floating construction.
The chosen case studies are purely meant as tools to bring these general concepts to life. They are not intended as concrete plans and therefore do not hold any status or impact on ongoing area developments or project implementations (such as the elaboration of the Merwehaven Masterplan). This applies to both the spatial designs and the presented number of residences.