A rectangular chute spillway is designed for gully erosion control with a drop (H) of 5 m, peak flow of 1.81 m³ s^-1 and maximum inlet water level of 0.81 m. Frictional head loss over the apron is 20% of H. The design height of chute blocks is equal to the depth of flow in the water way. Acceleration due to gravity (g) is 9.81 m s^-2. If coefficient of discharge of the weir section is 1.66, height of the chute blocks is