Analysis-Existing Conditions Prepared by Civil Core Consulting HydroCAD® 10.20-7a s/n 13637 © 2025 HydroCAD Software Solutions LLC
NOAA 24-hr D 10 YR-F Rainfall=6.17" Printed 8/29/2025
YR-F Rainfall=6.17" Printed 8/29/2025 Page 78
Summary for Subcatchment 17S: DA-E4A
Runoff = 0.25 cfs @ 12.35 hrs, Volume= Routed to Link 18L : Offsite
0.045 af, Depth= 1.84"
Runoff by SCS TR-20 method, UH=Delmarva, Split Pervious/Imperv. UI as Pervious, Time Span= 0.00-72.00 hrs, dt= NOAA 24-hr D 10 YR-F Rainfall=6.17"
Area (ac) CN Description
0.230 55 Woods, Good, HSG B
0.050 61 >75% Grass cover, Good, HSG B
0.010 98 Roofs, HSG B
0.290 58 Weighted Average
0.280 56 96.55% Pervious Area
0.010 98 3.45% Impervious Area
9.2 18 0.0200 0.03 Sheet Flow, Woods: Dense underbrush n= 0.800 P2= 3.42" Using McCuen-Spiess flow length
2.1 158 0.0200 1.27 Shallow Concentrated Flow, Cultivated Straight Rows Kv= 9.0 fps
2.1 62 0.0030 0.49 Shallow Concentrated Flow, Cultivated Straight Rows Kv= 9.0 fps
4.4 231 0.0300 0.87 Shallow Concentrated Flow, Woodland Kv= 5.0 fps
19.5 555 Total
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.7 86 0.0300 0.87 Shallow Concentrated Flow, Woodland Kv= 5.0 fps