Darcy, Henry

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Darcy, Henry

French Hydraulic Engineer
1803–1858

No other name is more closely associated with the field of hydrology than that of Henry Darcy. His expression for the movement of water through an aquifer , known as Darcy's Law, is still used today.

Henry Philibert Gaspard Darcy was born in Dijon, France, the capital of the Department of Côte d'Or. In 1826, Darcy received his degree in Civil Engineering from the School of Bridges and Roads in Paris, a specialty institution of the Corps of Bridges and Roads. Upon graduating in the top tier of his class, he was appointed to the prestigious Corps as an engineer, and soon accepted a position in his hometown.

Creating a Water Supply System

Upon his return to Dijon, Darcy undertook the task of creating a sanitary, efficient public water-supply system for the city and his proposal was accepted with no modifications. The plan included: the Rosoir spring as the water source; an underground aqueduct through which the water would travel over 12 kilometers (7.4 miles); two reservoirs ; 28,000 meters (91,800 feet) of underground pipes; and 142 public street fountains.

The project was completed in 1844, by which time Darcy had received the Legion of Honor award and the appointment of Chief Engineer for the Department of Côte d'Or. He was offered 55,000 francs as compensation for his project, but declined the payment and instead accepted only a gold medal and free water for the rest of his life. The public water system was a tremendous achievement not only because it greatly increased the quality of life for an entire city, but also because it was completed 20 years before anything of its kind in Paris.

Other Projects.

In the next few years Darcy moved on to several railroad and canal projects. Before long, during the revolution, he was exiled from Dijon because of his affiliation with the former government. He moved to Paris, but soon poor health forced him to resign from his engineering duties and he again returned to Dijon. He devoted his last years to performing laboratory experiments on the flow of water through sand columns and pipes.

Appendix D and Darcy's Law

In 1856, Darcy published "The Public Fountains of the City of Dijon," a report detailing the engineering that was used for Dijon's water supply, with the results of the sand column experiments included in the report's Appendix D. The experiments with pipes resulted in the Darcy–Weisbach friction coefficient, a value used to account for resistance to flow through an individual pipe.

Found only at the end of his report, Appendix D contained the groundbreaking work for which Darcy is best known: Darcy's Law. Simplified, this linear rule demonstrates that the rate of flow of water through a porous medium is proportional to the slope between two points of water at different heights, and that it flows from the higher to the lower point. Darcy's Law also takes into consideration the area of the medium and its ability to transport water (i.e., its permeability). Scientists now use this analytical approach to hydrology worldwide.

In 1858, Henry Darcy died of pneumonia and was buried in Dijon. The next day, to honor one of the most important, selfless contributors to the life of Dijon and the world of science, the Town Square was renamed to Place Darcy.

see also Aquifer Characteristics; Groundwater; Groundwater, Age of; Modeling Groundwater Flow and Transport.

Amy B. Parmenter