Glossary of Karst and Cave Terms

Darcy-Weisbach equation

An empirical equation given as which states that in contrast to laminar flow, the average volumetric discharge of flow is directly proportional to the square root of the driving force and that the friction loss is equal to the hydraulic head [5]. Note: Q=discharge, A=crosssectional area, R=hydraulic radius of the conduit, g=gravitational acceleration, f=some friction factor, dh/dL=gradient, and I have attached a negative sign to indicate that ground-water flow occurs in the direction of decreasing head. In most instances, a negative sign is not included because it is not possible to take the square root of a negative number.