Frank Spaargaren (20 December 1940 – 4 October 2020) was a Dutch hydraulic engineer who was one of the main designers of the Oosterscheldekering and served as a director of the Waterloopkundig Laboratorium in Delft.

Ordinarily, these gates remain open, permitting natural tidal movement, but can be securely closed during inclement weather conditions.

In 1995, Spaargaren returned to the Waterloopkundig Laboratorium (Hydraulic Research Laboratory) in Delft, where he served as interim general director until his retirement in 1997.

[1] Spaargaren published a number of research reports and technical publications throughout his career, including collaborations with other notable engineers and mathematicians such as Jo Johannis Dronkers.

[11] Along with other engineers, Spaargaren had expressed opposition to elements of the Dutch Government's Delta Programme Strategy, warning that it was insufficient to cope with the threat of climate change, specifically sea level rise.

In a 2018 letter to the Dutch House of Representatives, he noted, "The dikes have proven capable of withstanding significantly higher water levels than those currently anticipated.