1. S Curves
From Mays, 2011, Ground and Surface Water Hydrology

2. Example
The 1- hr unit hydrograph for a watershed is given below. Determine the 2 hr unit hydrograph.
Time ( hr) 1 2 3 4 5 6
Unit hydrograph ( cfs) 10
100
200
150 50

3. S Curve to Develop 2 hr unit hydrograph

4. Problem 8.5.3 Suppose the 4-hr unit hydrograph for a watershed is
Determine the 2-hr unit hydrograph
A design storm has 1 cm/hr in first 2 hr and 0.5 cm/hr in the second 2 hr. Baseflow = 10 m3/s. Calculate the total runoff hydrograph
Time (hr) 2 4 6 8 10 12 14
Unit hydrograph (m3/s/10 mm) 15 45 65 50 25

5. Problem

6. Problem

7. Determining the  index and Excess Rainfall Hyetograph