Water availability and drought over long term

The availability of sufficient freshwater, for all users and functions, is also an increasingly big challenge in the Netherlands and Flanders. A solution is being sought in self-provision at the regional and local levels, along with a maximum possible efficiency in the exploitation of freshwater sources. For the drinking water sector this will require going beyond the well-trodden paths in its thinking, as indicated by the Beleidstafel Droogte (Drought Policy Committee) among others.

In this theme-overarching research project, we detail the knowledge base required by the drinking water sector in order to bring about the water transition that drinking water utilities, Water Authorities and nature organisations aspire to.

Water systems thinking as basis

Through an approach known as ‘water systems thinking’, an understanding can be gained of the consequences of new connections between sectors, or of the more economical use of water in the water cycle. What is important here is to understand the repercussions (both positive or negative) of a measure taken in one location or sector on other sectors. Thus, for instance, the use of residual water or surface water for drinking water, industry or agriculture, should not lead to the drying out of streams; or a solution for water quantity should not result in problems with the water quality.

This water systems thinking generates conceptual models at the provincial level or at the level of a drinking water production location. These can be used to gain a clear picture of where and how problem areas arise, and of which measures best balance regional water demand and supply.

Understanding of adaptation possibilities

Insight is needed into the technical possibilities and effectiveness of methods to achieve a better balance between the retention and discharge of water and the increase of water availability. The water sector has developed numerous methods over the last decades aimed at improving water stock building. The focus was on the West Netherlands, applying different infiltration and recovery systems which use surface water as a source. This involves very large-scale MAR systems in the dunes, but also smaller ASR systems at greenhouse horticultural locations, among others. Alternative sources also are considered, for instance the abstraction of polder water or of brackish water, and the large-scale abstraction of bank-filtration water along rivers, or even the use of WWTP effluent. Are such techniques also suitable for larger scale application in Pleistocene areas, and what adjustments would have to be made?

The side-effects of these solutions also need to be borne in mind. For instance, the large-scale delivery of surface water effectively addressed the drought damage caused by groundwater abstraction in the East Netherlands, but it also resulted in a deterioration of local water quality. Along with technological solutions, land-use and water-management measures are also very relevant. How much can be achieved through a different land-use or by the increase of the drainage base or by discharge containment? Would this be at the cost of water quality? And what implications would these measures have for other functions?

Behaviour and perception of drinking water customers

Lastly, an understanding of water demand also requires knowledge about the behaviour and perception of the drinking water customer. In this regard the central question concerns how much, and by what means, water conservation can be stimulated among (private) customers.

The effectiveness and the water-conservation potential of different behaviour influence techniques remain unclear. The same can be said about the effect of potential technical measures (e.g., implementation of greywater systems), economic measures (e.g., introduction of peak and off-peak rates, or of tiered rates), and regulatory measures (e.g., watering restrictions).

Lastly, there is a need for knowledge about how customers perceive the safety and desirability of possible alternatives, including the (re)use of grey- and rainwater, and how their acceptance can be increased among different types of customers.