Abstract
Rectangular notch is one of the discharge measuring tools that are usually used in irrigation and drainage channels. The most essential parameter of the notch discharge equation is the coefficient of discharge C-d. This study aims to investigate experimentally the variation of the coefficient of discharge C-d with the rectangular notch hydraulic and geometric parameters such as water head h, notch height p, notch width B, and notch thickness t. The results show that the coefficient of discharge C-d increases with an increase of h and B while it decreases with t. There are no changes in the variation of actual discharge Q(act) and consequently the discharge coefficient C-d with h for notch height p more than 6 cm. An empirical formula was developed based on the dimensional analysis principle that can be used to predict the coefficient of discharge C-d value for the rectangular notch with known hydraulic and geometric data (h, B, p, and t).