Abstract

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.

Key words: Agricultural water, discharge, natural stream, entropy.