The Colding equation for soil drainage: Its origin, evolution, and use

The derivation of the ellipse equation by the Danish engineer Golding in 18 72 marked the beginning of a new epoch in the field of soil drainage. Littl e is known about the circumstances that led to the derivation of this equat ion or about the evolution of the Golding equation in later years. Therefor e, we decided to survey the early European literature on these subjects. Th e survey revealed that Golding's derivation was based mainly on research pu blished by the French engineer Delacroix in 1859 and by the Danish engineer Hannemann in 1870. Although Golding used soil water now concepts as develo ped earlier by Darcy and Dupuit, it is possible he was not familiar with th e work of these French engineers. After Golding's equation had been widely used for drainage design purposes in Denmark, his equation appeared in the German literature around the turn of the century. From Germany, the Golding equation spread to other European countries and to the USA. In the 1930s a nd the 1940s, the Golding equation was modified by Hooghoudt in the Netherl ands and by Aronovici and Donnan in the USA. The Hooghoudt equation is used today as a drainage design standard in various parts of the world.