Determining water flow discharge in open channels is a very important task for agricultural water management, but current methods are labor-intensive and difficult. The entropy method suggested by Chiu and Said (1995) promises to simplfy the task of measuring water flow rates. This paper offers a further simplification of ongoing discharge measurements by showing that the u(max) and H(max) values form a constant in a specific water channel cross section. Once the u(max)/H(max) constant is determined, u(max), and therefore discharge, can easily be calculated from H(max) measurements. This method, which we call Q(umax) method in this paper, was compared against the integrated discharge method for accuracy and was found to have an accuracy similar to that of two other common methods, the integrated Q(0.2) to (0.8) and the entropy methods (Q(Mi)). Comparisons were carried out at four sites along the tributaries of the Kizilirmak river in central Anatolia, Turkey.