Hydrologists are often required to audit closed conduit flowrate in which venturi meters or orifice plate meters, etc., are employed to measure flow in pipes running full. These meters are based on the principle that when water passes through a contraction in a pipe, it accelerates. The resulting increase in kinetic energy is balanced by a decrease in the static pressure at that point in the pipe and the pressure drop caused by the contraction is proportional to the square of the flowrate for a given flowmeter.