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<p>Partially contracted rectangular sharp-crested weirs (PC-RSCW) have the width of the rectangular crest to channel width (<i>b/B</i> &gt; 0.3). The discharge coefficient (<i>C</i><sub>d</sub>) of these weirs depends on various parameters necessary to be evaluated. Hence, the present study investigates the flow over PC-RSCW in a laboratory model with <i>b/B</i> = 0.2917, 0.3333, 0.3750, and 0.4167 and heights (<i>P</i> = 0.1&#xa0;m) for flow discharges (<i>Q</i> = 0.7 to 4.9 L/s) and reveals the role of parameters affecting the discharge coefficient through sensitivity and statistical analysis. The variations of flow discharge (<i>Q</i>) with head over the weir (<i>h</i>), <i>C</i><sub>d</sub> with <i>h/b</i>, <i>h/P</i>, and <i>b/B</i>, and the measured and actual discharges were compared, and the discharge error values were calculated. Results indicated that in the partially contracted region, <i>C</i><sub>d</sub> reduced suddenly in <i>b/B</i> = 0.3333 and then increased by increasing <i>b/B</i>. The largest and the smallest maximum discharge errors between the present data and previous formulas were less than 17% and 3%, respectively. Finally, a calibrated novel equation was proposed for <i>C</i><sub>d</sub> based on <i>b/B</i>, <i>h/b</i>, and <i>h/P</i> with <i>R</i> = 0.9816, RMSE = 0.0007, MAPE% = 0.4232, SI = 0.0057, BIAS = 0.0018, and KGE = 0.8237. Sensitivity and statistical analysis results were provided to predict <i>C</i><sub>d</sub> of PC-RSCW in a laboratory channel with small discharges.</p>

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Discharge coefficient investigation of rectangular sharp-crested weir under partially contracted condition

  • 期刊论文

  • 发表日期：

    2025年8月19日

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  • Mehdi Hamidi,
  • Ali Mahdian Khalili

摘要

Partially contracted rectangular sharp-crested weirs (PC-RSCW) have the width of the rectangular crest to channel width (b/B > 0.3). The discharge coefficient (Cd) of these weirs depends on various parameters necessary to be evaluated. Hence, the present study investigates the flow over PC-RSCW in a laboratory model with b/B = 0.2917, 0.3333, 0.3750, and 0.4167 and heights (P = 0.1 m) for flow discharges (Q = 0.7 to 4.9 L/s) and reveals the role of parameters affecting the discharge coefficient through sensitivity and statistical analysis. The variations of flow discharge (Q) with head over the weir (h), Cd with h/b, h/P, and b/B, and the measured and actual discharges were compared, and the discharge error values were calculated. Results indicated that in the partially contracted region, Cd reduced suddenly in b/B = 0.3333 and then increased by increasing b/B. The largest and the smallest maximum discharge errors between the present data and previous formulas were less than 17% and 3%, respectively. Finally, a calibrated novel equation was proposed for Cd based on b/B, h/b, and h/P with R = 0.9816, RMSE = 0.0007, MAPE% = 0.4232, SI = 0.0057, BIAS = 0.0018, and KGE = 0.8237. Sensitivity and statistical analysis results were provided to predict Cd of PC-RSCW in a laboratory channel with small discharges.