Swiss physician, scientist, and founder of limnology, the study of lakes.

While lecturing in physiology and anatomy at the University of Lausanne, Switz., Forel began his investigations of lakes, notably Lake Geneva, and he published his findings in Le Léman: Monographie limnologique, 3 vol. (1892–1904). His standard work on limnology, Handbuch der Seenkunde (1901), included a study of the hitherto unexplained movement of lake waters known as seiches (seiche). Forel is credited with the discovery of density currents, which occur in the Alpine lakes because of the cold temperatures of entering glacier-derived streams. He also explained the mechanism of seiches and studied earthquakes and glaciers.