This research was conducted in the laboratory using an acrylic flume of 20 cm x 30 cm x 500 cm placed on the main flume of 45 cm x 60 cm x 740 cm. The base of the flume variations were made of surface roughness in the form of patches of cylindrical material with variations in the number of roughness (hr): 1,000, 1,016, 1,031, and 1,047, with a protrusion height of 4 mm and discharge variations of 1/4Q, 1/2Q, 3/4Q, and Q (Q= 7,471 l/s). Observations were made on changes in water level elevation. It was recorded using ultrasonic measuring devices. Analysis was carried out on the cross-sectional area of the hydraulic (A), the radius of the hydraulic (R), the circumference of the hydraulic (P), the slope of the energy line (S), the average velocity of flow (V), the roughness coefficient of manning (n), and the hr-n relationship , using the trend equation from Microsoft excel. The findings of this study were in the form of a mathematical formula of the relationship between hr and n namely n= 0.0014hr + 0.0344. The formula can be used to determine the n-value of a channel material based on the hr-value. Thus, an objective and measurable analysis result was obtained.
Volume 11 | 08-Special Issue
Pages: 2567-2578