(Solved): Example 6: Compound Channel The figure below shows a compound cross section for an open channel flo ...

Example 6: Compound Channel The figure below shows a compound cross section for an open channel flow due to flooding. A trapezoidal concrete lined channel is Region 1 below, where the normal depth of flow is $2\mathrm{m}$. The channel base width is $5\mathrm{m}$ and has side slopes of $1\mathrm{V}:2\mathrm{H}$. The Manning's n is 0.015 (Region 1). During large floods, the water level in the channel exceeds the channel-bank full level of $2.5\mathrm{m}$. The flood banks are $10\mathrm{m}$ wide and are grassed with side slopes of $1\mathrm{V}:3\mathrm{H}$ (Region 2 and Region 3 ). The estimated Manning's $n$ for these flood banks is 0.035 (Region 2 and Region 3 ). The bed slope SO is 0.001 for the whole compound channel. Estimate the discharge for a maximum flood level of $4\mathrm{m}$.