Question 2 (25p): The flowrate of the trapezoidal channel as shown in figure is 10 m/s. The channel bottom slope is 0.0008. The channel bottom and the side slopes are concrete with a Manning coefficient of 0.01; a) Design hydraulically most t economical channel (the best hydraulic section). b = [2h(1 + m-m)] b) Find the flow regime. c) After a heavy rainfall, the main channel given above expands with a flood plain as seen from the left figure. Find the flowrate of the new channel with a flood plain. Flood plain bed and it's slope is with grass -0.03 -0.03 5 m- bottom slope is also 0.0008) 0,01 1 m h n-0.01 b n-0,01 coefficient manning n=0.03. (The flood plain