Dry Canyon Study Design Hydrographs

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

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

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

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

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

TL=87 min. GA Params for Loamy Sand

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

Result with 3 ft orifice

Result with 5 ft Orifice

Actual design study model

Actual design study hydrograph

Effect of impervious areas Overall 10% area mapped as impervious Precip = 2.37 in Vol = 448.7 acre ft Vol from pervious 44.9 acre ft 44.9+13.6=58.5 Hydrograph without impervious area Conclusion: Precise quantification of the losses is critically important for this design and a source of significant uncertainty