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Farewell symposium: Dunes, coastal aquifers and artificial infiltration: towards a new equilibrium?

New thesis prize named after leading hydrogeology expert Stuyfzand

Over the course of forty years, hydrogeologist Pieter Stuyfzand has worked at Kiwa/KWR, Delft University of Technology and the VU-University of Amsterdam on a valuable corpus of knowledge relating to artificial infiltration, dune hydrology and groundwater quality. He is taking leave now that more and more of the knowledge he has developed is being put into practice throughout the world. A report on his farewell symposium, that culminated in a thesis prize bearing his name.

Pieter Stuyfzand’s farewell symposium was organised at KWR on Friday, 29 November 2019. Colleagues, former colleagues, family and friends looked back with him on his impressive forty-year career at KIWA/KWR, twelve years at the VU-University of Amsterdam and four years at Delft University of Technology. Host Jan Willem Kooiman opened the symposium with wonderful anecdotes about international post-conference field trips with Stuyfzand and others, and introduced the Kooiman classification for Stuyfzand, which describes the different phases in Stuyfzand’s career in line with the celebrated Stuyfzand classification for groundwater types (see H2O 1986, nr 19, p.562-568).

Corpus of knowledge with lasting practical value

The event provided an impressive demonstration of how the ideas that Stuyfzand has built up over the decades about the artificial infiltration of pre-treated surface water, dune hydrology and groundwater quality continue to have an effect in the present, and not only in Stuyfzand’s principal research location, the dunes. This pace of this development picked up sharply in response to Koen Zuurbier’s doctorate, which involved concrete pilot projects outside the dunes. In particular, the growing demand for regional freshwater supplies and, of course, the drought of 2018 led to ever-louder calls for the use of the subsurface. Stuyfzand is taking leave at a good time: in the Netherlands, and increasingly abroad in the not too distant future, the ideas he has developed over the past 40 years will be applied in practice more and more. His ideas are being picked up by other people, often people trained and/or inspired by him, and developed further.

Stuyfzand during his farewell presentation. (Photo: @Miriam Brunke)

New ways of safeguarding drinking water supplies

The first speaker to address substantive issues at the farewell symposium, Dr. Koen Zuurbier (PWN), completed his doctorate (on subsurface water storage in horticulture) with Stuyfzand at the VU-University of Amsterdam in 2016. Recently, after nine years as a colleague of Stuyfzand at KWR, he made the switch to a position as policy consultant at water company PWN. Zuurbier described how the availability of adequate supplies of drinking water will be under pressure in the future and how, among other things, the re-use of residual water and subsurface water storage are important new ways of safeguarding adequate and ongoing supplies of drinking water. And, of course, he looked back on working with Stuyfzand as a professor, doctorate supervisor and KWR colleague.

The Stuyfzand classification of water types in Belgium and worldwide

Professor Kristine Walraevens (University of Ghent) knows Stuyfzand mainly from the SWIM symposia (Salt Water Intrusion Meeting) and was inspired by the Stuyfzand classification, which she has been using since 1987 in her own research into the chemical composition of groundwater, not only in Belgium also in Morocco, Tanzania and Bangladesh. She drew on numerous examples to show how the spread of water types sheds light on the dynamics of salinisation, refreshing and other processes.

Pioneer in unravelling data

Many people know Pieter Stuyfzand as an inveterate Excel user, but Emeritus Professor Theo Olsthoorn, his former colleague at Kiwa and Delft University of Technology, showed that, even before the real digital era, he was already involved in fresh-salt modelling, but with the programmable HP41-CV. He presented an impressive overview of Stuyfzand’s work and fished out a number of dusty reports from his own archives. He showed how Stuyfzand has always been a pioneer in the detailed unravelling of data and literature in order to arrive at analytical solutions for issues relating to fresh-salt modelling.

Fresh and saline groundwater in coastal areas never in balance

Dr. Vincent Post, a former colleague of Stuyfzand at the VU-University of Amsterdam, talked about whether there is an equilibrium between fresh and salt groundwater in coastal areas on the basis of, among other things, the results of his research in Australia and on the island of Tarawa (Kiribati). He also concluded that it is already very important to use fresh groundwater in coastal areas in sustainable ways and that this can only become even more important in the future in the context of climate change and rising sea levels. With Stuyfzand, he also emphasised that it is essential to make adequate and reliable measurements to monitor the condition of the groundwater.

Five speakers during the farewell symposium: Koen Zuurbier (top left), Kristine Walraevens (top middle), Theo Olsthoorn (top right), Vincent Post (bottom left), and Roelof Stuurman (bottom right). (Photo: @Miriam Brunke)

Groundwater stress and geo-blunders around the world’s oceans

Drs. Roelof Stuurman (Deltares) first shared some wonderful family photos of Stuyfzand and himself in younger years. In the serious part of his presentation, he discussed a number of cases that show how important sound geohydrological research is for the success of projects in, for example, urban water management and the reconstruction of a city after a natural disaster. Sound collaboration between civil servants, contractors and research/knowledge organisations is essential in this respect; unfortunately, things still often go wrong there. Errors are usually swept under the carpet, with the result that no one bears responsibility and no lessons are learned.

The Dutch dunes, a testing ground for the world

The final part of the symposium was Stuyfzand’s plea for the sustainable shaping of Holland’s coastal dunes as a testing ground for the world in several research areas, with hydrology and water quality occupying centre stage. The special features of these dunes are their combination of important nature values, size, social relevance (sheltered and water extraction areas, including artificial infiltration, coastal defences) and high levels of typical stress from the surrounding areas (such as overpopulation, industrial activity, ports, air pollution and sea level rise). In addition, they represent a 150-year history of sound research into many areas, including the subsurface structure, water balance, groundwater flow and water quality, with and without artificial infiltration. In addition, that research is based on excellent observation wells (piezometer nests), which are often not present elsewhere in the world. After his talk, Stuyfzand turned the spotlight on the previous speakers.

During one of his intermezzos, Jan Willem Kooiman talked about how Stuyfzand and he have been working together for more than 25 years, always in a different relationship with each other. (Photo: @Miriam Brunke)

In addition to these speakers, KWR colleagues Klaasjan Raat, Niels Hartog and Idsart Dijkstra, and TU-Delft colleagues Mark Bakker and Timo Heimovaara, shared great memories and anecdotes.

New: the Pieter Stuyfzand Thesis Prize

A highlight of the meeting was the presentation of the Pieter Stuyfzand Thesis Prize (PSSP) by Dr. Niels Hartog, the chair of the Dutch branch of the International Association of Hydrogeologists, IAH-NL. From 2020 onwards, IAH-NL will award this prize annually to the student with the best thesis in the field of groundwater and geohydrology, and Stuyfzand himself will be involved in the selection of the winner.

Pieter Stuyfzand and Niels Hartog just after signing the agreement for the Pieter Stuyfzand Thesis Prize. Starting next year, the prize will be awarded annually to the student with the best geohydrological thesis. (Photo: @Miriam Brunke)

Celebrated figure at SWIM and ISMAR

During the past forty years, Stuyfzand was present at almost every congress of ISMAR (International Symposium on Managed Aquifer Recharge) or SWIM (Salt Water Intrusion Meeting). Partly thanks to the valuable presentations and courses he gave at these congresses, he has contributed a great deal internationally to the knowledge development and has acquired a famous reputation. That work also resulted in valuable contacts and friendships with international colleagues, such as speaker Kristine Walraevens (University of Ghent). Some other foreign friends/colleagues were unable to travel to the Netherlands and so they sent video messages to Stuyfzand and the symposium. David Pyne (USA), Russell Martin (Australia) and Peter Dillon (Australia) pointed out that Stuyfzand was indispensable in the development of MAR (Managed Aquifer Recharge).

Forty years at KIWA/KWR, twelve years at VU-University and four years at TU-Delft

It will come as a surprise to nobody who knows Pieter Stuyfzand that, at the reception after the symposium, he discussed his view of the past forty years of service in detail. Even after this symbolic farewell, Stuyfzand will continue to be active in his field as a private consultant and he will work on a book with the provisional title Analysis of flow and quality patterns in (coastal) groundwater systems with and without Managed Aquifer Recharge.

Pieter with his wife Loredana (right), daughters Julia and Eugenie (middle), and son-in-law Gadi (left). (Photo: @Miriam Brunke)