Where do drinking water utilities get their raw water from when the climate changes?

On 14 November, hydrologists, strategists and technologists from practically all of the drinking water utilities gathered at KWR to participate in a symposium in connection with the Joint Research Programme’s Klimaateffecten op winningen (Climate Impact on Abstraction) project. Public servants from various provinces and fellow researchers from RIVM, KNMI and KWR joined this gathering.

Climate impact can influence drinking water abstraction.

(Source) strategy

The report of the Climate Impact on Abstraction project (Klimaateffecten op winningen, in Dutch) had shown that the climate impact is potentially great for all types of abstraction. Apart from the use of robust treatment techniques, the drinking water utilities have little margin for manoeuvre: they are heavily dependent on their environment and have to operate with significant uncertainties. Climate change plays an important role in the (source) strategy of the drinking water utilities. This BTO research, undertaken at the initiative of Vitens and involving most drinking water utilities, indicated that there is a great need for the mutual sharing of knowledge.

Resilience of the water provision as a whole

Following the welcoming words by the day’s chairperson, Eric Broers (KWR), Sija Stofberg of KWR reviewed the results of the BTO research and pointed to several striking findings, such as the observation that drinking water utilities (must) increasingly focus on the resilience of the water provision as a whole, for example, by spreading the risk with regard to the sources.

2023 climate scenarios

Karin van der Wiel (KNMI) explained her institute’s new climate scenarios. Many professionals make use of the KNMI’23 climate scenarios. To apply the scenarios effectively, it is useful to know more about their background and the underlying choices that were made. The new scenarios were recently made public and, besides scenarios for high and low emissions of greenhouse gasses, also include two alternatives related to water. In all of the scenarios the summers are drier and the winters wetter compared to the last thirty years, but a distinction is made between the average annual water-logging or average annual desiccation. From the water sector’s perspective, it is the increase in summer droughts and the increase in extreme precipitation events that are of greatest relevance. At the end of this year data on the expected river discharges will also become available, and next year the updated Delta scenarios will be produced incorporating the new 2023 climate scenarios.

Reverse osmosis

Drinking water utilities each work in their own way on the climate resilience of the drinking water provision. Guido Kersten (Oasen) spoke about Oasen’s river-bank filtrate abstraction. When compared to surface water abstraction, this abstraction has relatively fewer difficulties with drought and low discharges, but could encounter problems caused by salinisation. For these reasons – but also with river-water pollution in mind – Oasen is looking at reverse osmosis as a treatment process.

Heel: learned by doing

Marie Louise Geurts (WML) described the process that has led to the current form of the water production company Heel, which was started in 1990 with the aim of reducing the use of groundwater. In 20 years, a production site has been set up with a reservoir in a former gravel pit. Over the years the abstraction has experienced various intake suspensions and installed a deep groundwater abstraction system as a back-up. In retrospect, it can be said that not all of the challenges were fully anticipated at the beginning, but that lessons were learned by doing. A word of advice to colleagues at other drinking water utilities facing similar challenges: think about what the complexity of the operational management might mean for the employees, and how you can prepare them for it.

Multi-source concept and sustainable integration of groundwater abstraction

Ate Oosterhof (Vitens) gave a presentation on the challenges faced by Vitens related to its wish to expand its abstraction in the short term. Vitens is currently working on a multi-source concept in the IJssel valley, in which it would be possible to switch among various sources: river water, river-bank filtrate, shallow groundwater and deep groundwater. A concept of this sort involves various (technical) challenges. Vitens is also examining the sustainable integration of groundwater abstraction, with concepts such as ‘de eeuwige bron’ (the eternal source) and ‘Panorama Waterland’ as examples.

You build drinking water abstraction systems for several decades

The mini-symposium concluded with an extensive discussion, for instance about the development of drinking-water demand projections and the challenges for drinking water utilities. Drinking water abstraction systems are built for several decades, which is why it is good to identify which discussions the water sector should initiate now.

Experts from drinking water utilities, KNMI, RIVM and KWR discussed the future of the drinking water provision.