He published his Ph.D. thesis on sand movement in the Strait of Dover (which was relevant for Dutch coastal morphology), based on extensive measurements in that area.

During the war, he prepared a plan called "Verlandingsplan" to manipulate tidal rivers in such a way that natural silting-up would take place, and that to reclaim this new land would be easy.

In 1939, Pieter Jacobus Wemelsfelder, a colleague of van Veen, published a paper in the journal de Ingenieur (English: The Engineer) that was the first to apply statistical methods to the occurrence of storm surges.

Despite these studies focusing on different aspects of storm surges, they arrived at the same conclusion: that the delta region of The Netherlands faced significant dangers.

The report identified significant deficiencies in the height of dikes - up to 1 metre in some areas - and highlighted vulnerabilities along critical waterways such as the Hollandse IJssel and the Merwede.

The commission provided detailed recommendations, including dike reinforcements, controlled land reclamation, and strategic closures of vulnerable waterways to mitigate the risk of catastrophic flooding.

[8] The report incorporated advanced hydrological and mathematical analyses for its time, examining factors such as astronomical tides, storm surges, high river discharge, and long-term sea level rise, which was projected at 20 centimetres per century.

Though the report's findings were not fully acted upon due to the outbreak of World War II, it laid the groundwork for post-war flood management initiatives and presaged the innovative engineering solutions later embodied in the Delta Works.

Notably, the report demonstrated van Veen's approach to integrating empirical data with predictive modelling to inform sustainable flood defence strategies.

[8] Van Veen published a book in English on the history of Dutch hydraulic engineering, titled Dredge, Drain, Reclaim: The Art of a Nation.

[9] In later editions, van Veen added a chapter under the pseudonym "Dr. Cassandra", using this alias to issue warnings about the pressing flood risks faced by the Netherlands.

His final advisory report, dated 29 January 1953, included a comprehensive study of these risks and a detailed plan to mitigate them by closing specific estuaries.

Just days later, the Netherlands was struck by the devastating North Sea flood of 1 February 1953, the worst storm surge in the country's history.

By May 1953, the commission released its first interim report, urgently recommending the closure of the Hollandse IJssel with a storm surge barrier and the implementation of van Veen’s plan to close the estuaries, which later became the basis for the Delta Works.