Freshwater shortages and more flooding: new Delta Scenarios show need for major steps this century

About the Delta Scenarios

The Delta Scenarios are published every six years. They are based on the latest insights from, among others, the Royal Netherlands Meteorological Institute (KNMI), the Netherlands Environmental Assessment Agency (PBL), Wageningen University & Research, and Deltares. They do not set out new policies. The scenarios provide an overall picture of developments that affect water policy, such as: climate change, activities to reduce greenhouse gas emissions, and socio-economic and spatial developments. With the knowledge from the Delta Scenarios, policymakers and agencies can get to work on effective approaches to keep the Netherlands safe and liveable.

Drier, but also wetter

The focus is on four scenarios between now and 2050 and 2100: Warm (Warm), Steam (Stoom), Rapid (Vlug) and Space (Ruim). All of them are possible and all of them must therefore be taken into consideration. In all four, the summers will get drier and winters wetter due to climate change, resulting in greater challenges. In Warm and Steam, climate change is strongest. In Rapid and Space, there is a strong global effort to reduce greenhouse gases. In Rapid and Steam, the population grows; in Space and Warm, there is more space for nature. These developments also place some demands on water policy.

Increasing water shortages

One of the most pressing agendas involves keeping fresh water available for all kinds of societal functions such as agriculture, shipping, nature, drinking water, energy, and industry. The amount of fresh water available during the summer period falls in all the Delta Scenarios because there will be long dry periods and more water will evaporate due to higher temperatures. There will also be shortages because less water will flow through our rivers in the summer and salt water will intrude further and further inland.

These developments will be exacerbated as the climate continues to change. On the other hand, demand for water will rise significantly in all scenarios, for example to flush water systems (to manage salinity), the irrigation of agricultural land, the expansion of nature reserves and higher demand for drinking water. A new factor requiring large amounts of water will be the raising of the groundwater level in low-lying peatland to combat subsidence and reduce carbon emissions. The equilibrium will be disturbed, and water shortages will become more frequent. Not all functions can be supplied with enough water at all times, with damage to society as a result.

Increasing problems with excess water

The probability of problems with excess water is also higher in all scenarios, in the summer because of peak rainfall and in the winter due to long periods of rain. Moreover, extreme conditions will coincide more often: intense rainfall and high river discharges and higher sea levels so that not enough water can be discharged. The damage can be considerable in both urban and rural areas. Flooding can be disruptive when roads are impassable, hospitals are no longer accessible, or when electricity or communication networks fail.

Floods with greater consequences

In all scenarios, we need to take action to maintain our protection against flooding at the same safety standard. The sea level will rise and river discharges will increase in winter. In addition, with more people living behind the dikes and more economic assets being located behind the dikes, floods will have more impact. The Flood Protection Programme is making the associated preparations for 2050. If global emissions are not reduced, the challenges relating to flood risk management will continue to increase after 2050.

Minister Mark Harbers (Infrastructure and Water Management): “The changing climate means we are already faced with dry summers and extreme rainfall. The scenarios show that the challenges relating to water can only increase in the future, while freshwater supplies are already under pressure now. It is clear that we must take measures against extreme weather; we are already working on this in all sorts of ways, such as steps to store more fresh water in the IJsselmeer that we can draw on during dry periods. And stricter regulations for building in floodplains. We can do even more: the scenarios show that winters will get wetter, which means that we need to do an even better job of retaining and storing that water to get through the drier summers. The Delta Scenarios make a valuable contribution to the revision of the Delta Programme in 2026 and the decisions that will be made in that respect in the 2027 National Water Programme. In this way, we aim to keep the country a safe and pleasant place for the foreseeable future.”

Delta Commissioner Co Verdaas: “The challenge of keeping our country liveable in the future is increasing. We will have to learn to live with too much, and too little, water. We have a centuries-old tradition of restraining and managing water. The classic approach of technical interventions in the water system is starting to pinch. We need to plan our country so that we can cope better with the extremes. This doesn’t happen on its own: it requires decisions that will affect our living environment and how we use our land and our water. In the periodical evaluation of the National Delta Programme, we will be preparing for those decisions in the years ahead. They are difficult decisions, but they will produce a future-resilient country.”

Dirk-Jan Walstra (director of Deltares): “The Delta Scenarios demonstrate that we will have to work hard to tackle all the urgent water agendas. As a country, we all benefit from an ambitious climate policy; otherwise, we will find it difficult to keep up with the pace of change required. Good water management, sensible spatial policies and sensible water use go hand in hand here. We are now facing fundamental decisions with a broad societal impact about the management of our water and soil systems. With our long history in smart water management, the Delta Scenarios help us to prepare now for decisions and effective action.”

Consequences for all

The Delta Scenarios show that water policy is facing major challenges. In all four Delta scenarios, the water agendas become more extensive. Bottlenecks relating to water shortages, problems with excess water and flood risk management are piling up. Everyone in the Netherlands will feel the pinch.

The bottlenecks are becoming increasingly structural in nature. That affects our entire country, and it will have consequences for all water users, including: drinking water supplies, keeping water in ditches fresh, and managing groundwater salinisation in the low-lying Netherlands, keeping low-lying peatland wet, nature, agriculture, shipping, and infrastructure construction and maintenance.

Using the Delta Scenarios

The Delta Scenarios are starting points for water policy, for the Delta Programme and the agencies concerned. But they can also be used in other areas such as in spatial policy (the National Spatial Policy Document) or the National Programme for Rural Areas. The scenarios help in policy development. They show where bottlenecks will arise in the medium and long terms, and where solutions are needed. In this way, we can prepare in good time and work adaptively on a safe and liveable Netherlands.