1. Questions from last time
What comprises a small watershed for the purposes of Snyders Unit Hydrograph?
Eqn 2-12: Tb=3 + tp/8 in days for tp in hours
By this method Tb is never less than 3 days. If you expect response to end in less than 3 days, then assume watershed is small and use Tb = (3 to 5) tp
What are the numerical values of SCS dimensionless unit hydrograph?
See for example:

2. S-Curve Method – to construct a UH of any Duration

3. Figure 2-9

4. Problem 2.14
Using Excel develop the S-curve for the given 3-hr UH and then develop the 2-hr UH from the 3-hr UH
Time (hr)
U(cfs) 1 75 2
180 3
275 4
280 5
210 6
130 7 60 8 30 9 15 10 11

5. Determining runoff from rainfall using Curve Numbers

7. Soil group mapped based on texture for all US Soils

8. Adjusting for Antecedent Moisture Class
From Chow, V. T., D. R. Maidment and L. W. Mays, (1988), Applied Hydrology, McGraw Hill, 572 p.

9. http://www. wsi. nrcs. usda. gov/products/W2Q/H&H/Tools_Models/WinTR55