Calculate equilibrium outflow; establish rating; calculate h_o from rating; calculate mean velocity v_o, and Froude number.

Equilibrium outflow q_e = iL = (65 mm/hr × 45 m × 0.001 m/mm) / (3600 s/hr) = 0.0008125 m³/s/m

Rating: q_e = b h_o^m

b = (1/n) S_o^1/2 = (1/0.08) (0.006)^1/2 = 0.968

Choose m = 5/3 [Manning friction in wide channels (overland flow)]; 1/m = 3/5 = 0.6

Calculate h_e = (q_e/b) ^1/m = (0.0008125/0.968)^0.6 = 0.014 m

h_o = h_e = 0.014 m

Calculate v_o = q_e / h_e = (0.0008125/0.014) = 0.058 m/s

Calculate F_o² = v_o² / (gh_o) = (0.058)² / (9.81 × 0.014) = 0.0245

Calculate K = (S_oL)/(F_o²h_o) = (0.006 × 45) / (0.0245 × 0.014) = 787 > 20.