The diagram below shows and outlet structure from a large detention basin consists of a concrete...

   

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The diagram below shows and outlet structure from a large detention basin consists of a concrete channel, which has a 8600mm wide vertical wall. Flow control is provided by a combination of three individual weirs and six orifices. 600 500 500 1300 350 350 300 3000 AHD 0 500 2000 HWL 77.500 m AHD 0 500 Pier HWL 77.500 m Crest of Upper Weir F TWL 75.900 m AHD Orifices Channel Base 74.300 m AHD Elevation (not to scale) Level of Channel Base 74.300 m AHD 1200 Crest of Lower Weir TWL 75.900 m AHD 0 Cross-sectional View (not to scale, dimensions in mm) Pier 300 Pier Plan View (not to scale) Each orifice has a diameter of 150 mm and a constant of C,-0.60. The weirs are located between two vertical piers and the channel walls. As a result of the central piers, it can be assumed that each weir acts as a "weir with end contractions". a. If the water level in the channel upstream of the control weirs is 77.500 m AHD and the water level downstream is 75.900 m AHD, determine the discharge flow rate in the channel. b. If the downstream water level in the channel rises to 76.80m AHD, and while the upstream water level remains unchanged, determine the flow rate in the channel. The diagram below shows and outlet structure from a large detention basin consists of a concrete channel, which has a 8600mm wide vertical wall. Flow control is provided by a combination of three individual weirs and six orifices. 600 500 500 1300 350 350 300 3000 AHD 0 500 2000 HWL 77.500 m AHD 0 500 Pier HWL 77.500 m Crest of Upper Weir F TWL 75.900 m AHD Orifices Channel Base 74.300 m AHD Elevation (not to scale) Level of Channel Base 74.300 m AHD 1200 Crest of Lower Weir TWL 75.900 m AHD 0 Cross-sectional View (not to scale, dimensions in mm) Pier 300 Pier Plan View (not to scale) Each orifice has a diameter of 150 mm and a constant of C,-0.60. The weirs are located between two vertical piers and the channel walls. As a result of the central piers, it can be assumed that each weir acts as a "weir with end contractions". a. If the water level in the channel upstream of the control weirs is 77.500 m AHD and the water level downstream is 75.900 m AHD, determine the discharge flow rate in the channel. b. If the downstream water level in the channel rises to 76.80m AHD, and while the upstream water level remains unchanged, determine the flow rate in the channel.