Multiple choice

A very wide rectangular channel carries a discharge of 8 m3/s per m width. The channel has a bed slope of 0.004 and Manning’s roughness coefficient, n = 0.015. At a certain section of the channel, the flow depth is 1 m.

At what distance from this section the flow depth will be 0.9 m? (Use the direct step method employing a single step)

  1. 65 m downstream

  2. 50 m downstream

  3. 55 m downstream

  4. 60 m downstream
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using the direct step method for GVF, the distance is calculated by delta_x = (E2 - E1) / (S0 - Sf_avg). Calculating the specific energy at depths 1 m and 0.9 m and the average friction slope leads to 50 m.

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