Question

Hydrologic analysis of a watershed Problem2: The unit hydrograph is the direct runoff generated by 1 unit (I mm in this problem) of excess rainfall. The one-hour unit hydrograph of a watershed is given by: 4 Time (hour) -0.9 U0.4 U0.2 0.0 0.0 U-0.6 Unit hydrograph (m/s/mm) (a) The 100-year storm over the watershed has the following excess rainfall pulses: Fromt 0 to 1 hour, P45 mm From t I to 2 hours, P20 From t = 2 to 3 hours, P,-75 mm From t-3 to 4 hours, P40 Compute the direct runoff hydrograph by using the discrete convolution approach (using the unit hydrograph and excess rainfall). That is, evaluate Qi, Q2, Qs, etc. (b) Assuming a constant baseflow of 1.0 m'/s in the river, evaluate and plot the total runoff hydrograph (c) What is the design flow value that should be used in the design of a downstream river or channel or culvert or spillway? -the depth of direct runoff ra (mm), (d) Compute: - and the volume of direct runoff Va (m) over the whole watershed. The watershed area is 7.56 Km

Answer 1

Dalo / Page RANKA 0-60904 h.2k 63 0 0.2 I ST 15 3 3 16m

Total-Kun-T te Assumea 3 . 45 dsphat, direct --ו 20 mm rn