Question

The maximum depth of water in a reservoir is maintained by a V-notch weir, as shown in the figurebelow.

Under storm conditions this weir is not adequate to cope with the excess flow and needs to bemodified. (a)If the maximum discharge, above which water will start to flow over the dam, is 55000m³/hr, determine the necessary height of the weir (H) if its discharge coefficient is 0.9. (b)One proposed new design is to increase the angle of the notch to 120°. Determine the maximum hourly discharge over this weir if the height of the weir remains the same as in part (a) and the discharge coefficient is 0.85. (c)A second proposed design is to replace the notch weir with a rectangular weir the same height as the original. Determine the width that this weir would need to be to give the same discharge as the proposed 120° notch.

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