The effluent of a wastewater treatment plant flows through a rectangular effluent channel with 0.8 m/s flow velocity. The effluent is discharged to a receiving body at an elevation of 228.0 m. At the discharge point, the invert elevation of the rectangular effluent channel is 229.5 m and at average flow conditions the water depth is measured as 0.7 m. The slope of this 75 m long effluent channel is 0.001. Find the water surface elevation at the beginning of