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.
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.
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.
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.
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.