Watershed runoff characteristics
Link to this table

Given:
Area = 50 ac. total watershed area in acres draining to pond
IC = 20 ac. new impervious area in acres (40%)
Watershed peak discharge and runoff volume:
Event Pre-development Post-development Unit
Q1-yr 24-hr 6.7 53.5 cfs
Q2-yr 24-hr 11.6 69.0 cfs
Q10-yr 24-hr 36.7 131.9 cfs
Q100-yr 24-hr 81.8 222.0 cfs
V1-yr 24-hr 0.3 3.9 ac-ft
V2-yr 24-hr 0.6 4.9 ac-ft
V10-yr 24-hr 3.1 8.9 ac-ft
V100-yr 24-hr 7.5 14.7 ac-ft