9.4.6.A mining company would like to replace an old flow monitoring weir. The contracted (one end), horizontal weir has a crest height of 23.5 ft, a crest length of 13 ft, and a discharge coefficient of 3.28 ft0.5/s. At design flow it operates with a head of 3.6 ft. Determine the crest height of a standard U.S.B.R. 90°-V-notch (replacement) weir that would discharge the same design flow without raising the upstream flow depth.

Fig: 1