The flow in a wide rectangular channel ( B+ 2y ≈ B) is gradually varied. The width of the channel is 2 m, bed slope is 1 in 1000 and the normal depth of flow is 1.5 m. The depth of flow at a section is measured to be 1 m. The slope of energy line with channel bed at a section where the depth of flow is 1 m is calculated using both Chezy’s formula and Manning’s formula. Determine the percentage of error (in %, up to two decimal places) occurred while estimation of the slope of energy line w.r.t to Manning’s formula.