Determination of Discharge Equation for Semi-Circular Broad Crested Weir Models

Abdullahi Umar, Umar Alfa Abubakar, Aliyu Adamu, Aminu Ohueyi Ahmed, Sani Yakubu Khalifa

Abstract


The discharge characteristics of semi-circular crested weir models were investigated. Two categories of weir were considered; normal weirs and oblique weir models. Both group of models had constant weir height of 20cm and had the crest radius varied three times; 5cm, 7.5cm and 10cm.Twelve models were fabricated and tested. Nine models with angles 90o, 60o and 15o as well as having radius of 5cm, 7.5cm and 10cm respectively were used in generating the discharge equation while three weirs models of radius 5cm, 7.5cm and 10cm at constant oblique angle of 30o were used in validating the equation. Multiple nonlinear regression analysis was used in determining the discharge equation while the validation was done using statistical methods (total error, coefficient of determination, coefficient of correlation, and reliability) with attention to accuracy, validity and goodness of fit of the generated equation. The investigation showed that for the developed discharge equation, the overall total error is 0.195. Coefficient of determination value is 0.994. The value of coefficient of correlation is 0.997 and the reliability of 1.911% in term of relative difference. It can be concluded that the generated equation is a very good option for calculating discharges for semi-circular broad crested weir, because it gave high coefficient of determination, very low total error, and a good reliability value.


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