help with this assignment, I am very lost. The equation to be used is at the top of the screenshot.

 

AR 2/3 So 1/2 Q = n byn (by)2/31/2 (b+2yn) 2/3 n | A drainage channel is to be installed to collect stormwater runoff from the Parking lot located East of Weaver labs (outlined in blue). The design flow rate to be conveyed by the channel is 1.25 cfs.The following drainage channel model has been selected for the installation (see images below). It comes in two widths: one that is 8 in wide and one which is 12 in wide. Your goal is to determine which channel should be used. (GPM is gallons per minute). 12" Filcoten Channel High-performance fiber-reinforced concrete trench drain system designed to handle heavy loads in pre- sloped and neutral configurations. Strong: Superior impact resistance compared to the competition Durable: Resistant to changes in temperature,exposure to UV, and non-flammable Environmentally Friendly: 100% recyclable, 0% harmful substances, 0% VOCs Learn More Slope 0.5% (Neutral also available) Material Fiber-Reinforced Concrete Max. Flow Rate 1094.24 GPM Channel Width 12" Grate Options Multiple Max. Load Rate Class E 2020 Google 8" Filcoten Channel High-performance fiber-reinforced concrete trench drain system designed to handle heavy loads in pre- sloped and neutral configurations. Strong: Superior impact resistance compared to the competition Durable: Resistant to changes in temperature,exposure to UV, and non-flammabl Environmentally Friendly: 100% recyclable, 0% harmful substances, 0% VOCs Learn More Slope 0.5% (Neutral also available) Material Fiber-Reinforced Concrete Max. Flow Rate 458.11 GPM Channel Width Grate Options Multiple Max. Load Rate Class E 1. Which drainage channel should be selected to convey the design flow rate? (Justify your answer). (10 pts) 2. Find the water depth in the drainage channel selected at step 1 for the design flow rate. (10 pts) - Assume uniform flow conditions Approximate the channel shape by a rectangle - Use the slope and width given in the channel specifications. - Use the handout to find the Manning coefficient for concrete (design value). 4. What is the flow state in the channel? (10 pts) Problem 2. Analysis of a drainage ditch A trapezoidal drainage ditch excavated in non colloidal alluvial silt conveys a flow of 14 cfs. The bottom width is 3.0 ft and the side slope is 4:1. The longitudinal slope is 0.0015 ft/ft. The ditch is subjected to high water tables.