Question

Explain in some detail the difference between a deterministic 'c' and a probalistic 'c' when using the Rational Formula? (a) Determine an estimate for the 100 year maximum discharge at Elmore (pre Lake Eppalock) on the Campaspe River given a selection of the information below: (b) 1) Area (A) 1240 square miles 2) C10 0.17 3) Length (L) 180 km (this include an allowance for river bends etc) 4) Slope (m/m) 2.77 x 10 5) Attached figures (Use the Melbourne relationship for L. F & D) (c) Compare your calculated flow with the Elmore record attached and comment on the difference. (d) Determine an estimate for a 1: 10000 year flood design peak? State any assumptions you may make.

Answer 1

The traditional deterministic rational method is so longer featured in ARR and is replaced by the probabilistic approach to application of this method. Q_y = 0.278cy I t_c, y A A = 1240 sq.miles C_10 = 0.17 L = 180 km slope = 2.77 times 10^- 4 m/m Q = AIR/360 m^3/sec