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Jo Johannis Dronkers (24 May 1910 – 20 February 1973) was a Dutch mathematician who is notable for the development of mathematical methods for the calculation of tides and tidal currents in estuaries. His work formed much of the mathematical basis for the design of the Delta Works. He attended the 1954 International Congress of Mathematicians in Amsterdam, where his work was discussed by David van Dantzig.

Life and career

Education and early work

Jo Johannis Dronkers was born in Poortvliet, the son of Willem Dronkers, a mayor, and Cornelia Pieternella van der Slikke. He had a twin brother, Johannis Jo Dronkers (1910-1993). He attended the State High School in Bergen op Zoom and then studied mathematics and physics at Leiden University. He completed his dissertation entitled "On stratifiable congruences" in 1939 under the supervision of Professor Willem van der Woude.

Although his work dealt with a problem in pure mathematics, it was notable for containing eleven propositions, five of which concerned tides. Three of these five propositions contained fundamental criticism of the work of Jannis Pieter Mazure, who at that time was one of the most influential people in the field of tidal calculations in the Netherlands. Amongst other propositions, Dronkers proposed a solution to the problem caused by the influence of upstream discharge on the calculation of tidal motion in downstream rivers.

Another of Dronkers' propositions concerned an inaccuracy in the work of Hendrik Lorentz contained in Lorentz's report on tidal movements as a consequence of the Zuiderzee Works.

Rijkswaterstaat and the Delta Works

In 1934, Dronkers commenced his career at Rijkswaterstaat, a Dutch governmental agency responsible for water management and civil engineering works. He was assigned to the Sea Arms, Lower Rivers and Coasts service, a division directed by Dr. Johan van Veen, where Dronkers focused on the mathematical study of tides and related hydrodynamic phenomena. His expertise contributed significantly to the post-war restoration efforts associated with the aftermath of the Inundation of Walcheren in 1945. Dronkers' role during this period is vividly described in A. den Doolaard's non-fiction novel Het verjaagde water, in which he is described as "The Calculator."

Dronkers' collaborative work with notable engineers like Frank Spaargaren led to several key publications in hydraulic engineering, particularly on topics such as tidal basin closures. His work gained further prominence following the devastating North Sea Flood of 1953, as he became deeply involved in the Delta Works project, a series of major civil engineering projects built to protect the Netherlands from sea flooding. Between 1949 and 1963, Dronkers served at the Central Study Service of RIjkswaterstaat, later renamed the Directorate for Water Management and Water Movement, under the leadership of Ir. J.B. Schijf. Here, as the chief mathematician, he played an integral role in the early studies that shaped the Delta Plan.

In 1963, Dronkers took over as head of the hydrological department of the Delta Service, succeeding Ir. H.A. Ferguson. His mathematical acumen was crucial in devising tidal calculations for the Delta Works. The earlier Delta Commission Report of 1961, to which Dronkers contributed, focused extensively on storm surges and tidal motion, and included work by other notable Dutch engineers like Pieter Jacobus Wemelsfelder. Dronkers' work was pivotal in transitioning from empirical approaches to more scientifically robust computational methodologies in hydraulic engineering. His analytical techniques allowed for a proactive assessment of hydraulic interventions, thereby laying the groundwork for evidence-based strategic planning in the field. This approach continues to influence much of hydraulic engineering.

Dronkers published his magnum opus, Tidal computations in rivers and coastal waters, in 1964. It remains a benchmark in the field of tidal calculation theory, and led to the award of the Conrad Medal by the Royal Netherlands Institute of Engineers to Dronkers in 1965. However, the book’s reception was not without controversy in the hydraulic engineering community. Dronkers' computational approach, though rigorous, was criticized by Johan Van Veen for its complexity and computational demands, which he believed could hinder timely practical applications. Instead, Van Veen proposed the use of an electrical analogue, which led to the use of the Deltar analogue computer. Conversely, the notable Dutch civil engineer Johannes Theodoor Thijsse advocated for a physical model-based approach.

Bibliography

• Dronkers, J.J. (1975). "Tidal Theory and Computations". Advances in Hydroscience. 10: 145–230. Archived from the original on 17 June 2023. Retrieved 22 November 2024.
• Dronkers, Jo Johannis (1939). Over stratifieerbare congruenties [On Stratifiable Congruences] (in Dutch). Amsterdam: H.J. Paris. p. 76. Retrieved 22 November 2024.
• Dronkers, J.J. (1964). Tidal Computations in Rivers and Coastal Waters. North Holland Publishing Company. Retrieved 22 November 2024.
• Dronkers, J.J.; Schönfeld, J.C.; Waalewijn, A. (1959). Tidal Computations in Shallow Water - Report on Hydrostatic Levelling across the Westerschelde (Rijkswaterstaat Communications 01 ed.). Rijkswaterstaat. Retrieved 22 November 2024.
• Dronkers, J.J.; Breusers, H.N.C.; Vinjé, J.J.; Venis, W.A.; Spaargaren, F. (1968). "Closure of Estuarine Channels in Tidal Regions". De Ingenieur. Retrieved 22 November 2024.

A list of many of Dronkers' reports is available at the website of the Trésor der Hollandse Waterbouw.

References

1. ^ van Dantzig, D. (1954). "Mathematical problems raised by the flood disaster 1953". Proceedings of the International Congress of Mathematicians, Amsterdam Sept. 2 - 9. Amsterdam: 218–239. Retrieved 15 December 2023 – via Wageningen University.
2. "Eendrachtbode /Mededeelingenblad voor het eiland Tholen 15 december" [Communications bulletin for the island of Tholen, 15th December 1983]. Krantenbank Zeeland (in Dutch). 15 December 1983. Retrieved 17 June 2023.
3. ^ Dronkers, J. J. (1939). Over stratifieerbare congruenties [On stratifiable congruences] (Thesis) (in Dutch). Leiden University. Retrieved 17 June 2023.
4. "Jo Dronkers - The Mathematics Genealogy Project". www.mathgenealogy.org. Retrieved 15 December 2023.
5. Mazure, J. P. (1963). "Hydraulic Research for the Zuiderzee Works". Van Douwen, A.A. (1963) Selected Aspects of Hydraulic Engineering, Liber Amicorum Dedicated to Johannes Theodoor Thijsse, on Occasion of His Retirement as Professor. Delft Technological University. Retrieved 17 June 2023.
6. Lorentz, H.A.; Wortman, H.; van Everdingen, E.; Stoel, W.F. (1926). Verslag van de commissie Lorentz (gevolgen afsluiting Zuiderzee op het getij) [Report of the Lorentz Committee (Effects of the Closure of the Zuiderzee on the Tide)] (in Dutch). Algemene Landsdrukkerij. Retrieved 28 December 2023.
7. Den Doolaard, A. (1948). Het verjaagde water [Roll back the sea] (in Dutch). Amsterdam: N.V. Em. Querido Uitgeversmaatschappij.
8. Dronkers, J.J. (1949). "De exacte methode voor getijberekening met als toepassing de berekening van de getijvoortplanting bij enkele theoretische stormvloeden" [The exact method of tidal calculation with examples of its application to the calculation of several theoretical tide surges]. Rapport Studiendienst (in Dutch). 's-Gravenhage: Rijkswaterstaat.
9. Waterloopkundig Laboratorium (WL); J.D. van der Tuin (1 May 1996). Studies naar het ontstaan van stormvloeden in Nederland: Een beknopt historisch overzicht tot 1980, met biografische aantekeningen [Studies on the Origin of Storm Surges in the Netherlands: A Concise Historical Overview until 1980, with Biographical Notes] (Report) (in Dutch). Vol. Tijdschrift voor Waterstaatsgeschiedenis, jrg. 5 (1996), nr. 1, p. 1-10. Waterloopkundig Laboratorium (WL) = Delft Hydraulics Laboratory. p. 10. Retrieved 15 December 2023.{{cite report}}: CS1 maint: multiple names: authors list (link)
10. Maris, A.G.; De Blocq van Kuffeler, V.J.P.; Harmsen, W.J.H.; Jansen, P.P.; Nijhoff, G.P.; Thijsse, J.T.; Verloren van Themaat, R.; De vries, J.W.; Van der Wal, L.T. (1961). "Rapport Deltacommissie. Deel 5. Bijdragen 4: Onderzoekingen betreffende de opzet van het Deltaplan en de gevolgen van de werken" [Report of the Delta Commission. Part 5. Contributions 4: Investigations regarding the setup of the Delta Plan and the consequences of the works]. Deltacommissie Deel 5, Bijdrage 4 (in Dutch). SDU. Retrieved 17 June 2023.
11. Dronkers, J.J. (1953). Colloquium over hoge waterstanden, 2: Over de hoogste waterstanden langs de Nederlandse kust [Colloquium on High Water Levels, 2: On the Highest Water Levels along the Dutch Coast]. SD 11b/53 (in Dutch). Stichting Mathematisch Centrum. Statistische Afdeling.
12. Dronkers, J.J. (1975). "Tidal theory and computations". Advances in Hydroscience. 10. Elsevier: 145–230. doi:10.1016/B978-0-12-021810-3.50007-2. ISBN 9780120218103. Retrieved 17 June 2023.
13. Dronkers, J.J.; Schönfeld, J.C.; Waalewijn, A. (1959). "Tidal Computations in Shallow Water: Report on Hydrostatic Levelling Across The Westerschelde". Rijkswaterstaat Communications. The Hague, Netherlands: Rijkswaterstaat. Retrieved 18 June 2023.
14. Dronkers, J.J.; Breusers, H.N.C.; Vinjé, J.J.; Venis, W.A.; Spaargaren, F. (1968). "Closure of estuarine channels in tidal regions". De Ingenieur. 80 (44). Koninklijk Instituut van Ingenieurs: 127–178. Retrieved 18 June 2023.
15. Dronkers, J.J. (1964). Tidal computations in rivers and coastal waters. Amsterdam; New York: North-Holland Pub. Co.; Interscience Publishers. Retrieved 17 June 2023.
16. Van Veen, J. (1946). "Electrische nabootsing van getijden: Commentaar van dr J. J. Dronkers, met naschrift van de auteur" [Electrical Simulation of Tides: Commentary by Dr. J. J. Dronkers, with Postscript from the Author]. De Ingenieur (in Dutch) (17). Koninklijk Instituut van Ingenieurs: 70–78. Retrieved 18 June 2023.
17. Van Den Ende, J. (1992). "Tidal calculations in the Netherlands, 1920-60". IEEE Annals of the History of Computing. 14 (3): 23–33. doi:10.1109/85.150066. ISSN 1058-6180. Retrieved 17 June 2023.

External links

• Repository of a number of publications by Dronkers (mostly in Dutch)

• 1910 births
• 1973 deaths
• People from Zeeland
• Dutch mathematicians
• Leiden University alumni