The project

Knowing what the River Rhine is 'doing' - bringing in too much or too little water from Germany and Switzerland - is a vital factor in terms of water supplies in the Netherlands. The faster climate change becomes, the larger the impact on our freshwater reserves. Not only when there is too much water, but precisely when there is too little, we all feel the effects: from ordinary households to agriculture and industry. The Freshwater Delta Decision directs the choices we make in the Netherlands and the steps we want to make with respect to the water system. Or user functions such as irrigating land. The discussion about this issue has been, and continues to be, conducted at the local and regional level in a dynamic context with large numbers of different interests. Fresh water is a factor that affects the economy and utilities when there are water shortages, or even when shortages become possible.

Our role in the Netherlands and the results

In 2014, we supplied the quantitative assessment of the effects of scenarios and promising measures. This involved an iterative process with many parties involved in the Delta Programme. For example, we identified the measures needed to make supplies of fresh water more robust, or precisely to reduce water demand, when those measures will be needed and to what extent. One of the adaptation measures involves the more frequent use of smaller routes for water recharge. An example is the inlet near Gouda, which will be closed more often if extremely low discharges become more frequent in the future.

We looked at the effects of these measures, and others. Those effects include changes in groundwater levels, problems with agriculture and shipping, limitations on the intake of drinking water or changes in ecological values. This process involved using the complex Delta Model, which combines water system analysis and the determination of the impact made by water users (agriculture, shipping, nature, drinking water, water for industry and cooling water). However, we also use smart calculation tools to analyse a whole range of options quickly and then to discuss them immediately in the policy-making process.

On the basis of the results, the Delta Commissioner was able to make changes to the adaptation strategy. The Dutch Lower House and other government authorities then approved the recommendations of the Delta Commissioner about the Preferred Freshwater Strategy for the 21st century.


There will be a follow-up to the Freshwater Delta Decision. In addition to follow-up research for phase 2 of the Delta Programme, Deltares also launched a stress test in the latter half of 2014. The question here is whether the Preferred Freshwater Strategy will still be feasible if a number of major projects are implemented, putting further pressure on freshwater supplies. This study is intended to clarify, among other things, whether the system will still be robust if there is a stacking-up of the negative effects of climate change, rising demand for fresh water and interventions such as the deepening of the New Waterway near Rotterdam, a salt variant of the Volkerak-Zoommeer lake or a large new sea lock in IJmuiden. The results will be presented in 2015.

Deltares experts

Judith Ter Maat, expert integrated water resources

It was fascinating to see how the results of the research, which were often still "hot off the press" were discussed in the dynamic policy-making process. That made the study extremely dynamic, and sometimes complicated, but the result was excellent!

Marnix van der Vat, expert water management and economics

The nice thing about working on these studies is that we cover all aspects relating to the use of water and that we have to provide arguments for the selection of particular measures, and the distribution between different functions when there are water shortages. The economic grounds for these decisions are not yet complete and we will be continuing to work on that area in the years to come. That will take us a step further in the field of water management than most of our neighbouring countries.

Joachim Hunink (left), Marnix van der Vat (middle), Judith ter Maat (right)