Austrian hydraulic engineer, one of the most significant contributors to the study of groundwater hydrology during the late 19th and early 20th centuries. He showed that many of the standard techniques of mathematical physics could be applied to problems of groundwater movement, establishing this subject on a firm scientific basis.

Forchheimer's chief contribution was the application of Laplace's equation to the phenomena of groundwater flow. Because the equation already had been thoroughly studied in relation to the phenomena of heat flow and fluid flow, a whole body of preexisting mathematical theory became available for the solution of problems of groundwater flow. See also Laplace's equation.