1. Dry Canyon Study Design Hydrographs

2. TL=52 min. GA Params for Loam
This uses streamstats average slope of 53%

3. Design Study 6 hour Hydrograph
From Anderson Consulting Dry Canyon Design, 2006

4. TL=87 min. GA Params for Loam
This uses longest flow path length slope of 19% that results in longer lag time

5. TL=52 min. K=2.1 in/hr (smallest in soil tests)
Note significantly smaller discharge volume and peak

6. TL=52 min. CN=63. 12 Hr freq storm

7. TL=87 min. GA Params for Loamy Sand

8. Detention basin geometry
The sides A, B, C, and D are sloped 1:2, 1:2, 1:5, and 1:1, respectively

9. Result with 3 ft orifice

10. Result with 5 ft Orifice

11. Actual design study model

12. Actual design study hydrograph

13. Effect of impervious areas
Overall 10% area mapped as impervious
Precip = 2.37 in
Vol = acre ft
Vol from pervious 44.9 acre ft
=58.5
Hydrograph without impervious area
Conclusion: Precise quantification of the losses is critically important for this design and a source of significant uncertainty