Question

2. The figure below represents the hydrological response (a total precipitation depth of 2-in in 24 hours), for a 200 acres watershed before and after the headwaters and central area of the watershed have been developed. The ordinance for the county where the development was observed requires you to design a pond (58 ft deep) capable to hold the entire additional volume of runoff that exceeds the hydrologic response observed before development. 4+? 18 | Qp = lofth 3 16 -Post-Development -Pre-Development A=87120 14 12 $712 10 Runoff Discharge (ft”/s) V: 1.148 مرت 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Time (hr) a. (10 pts) Estimate the runoff volume (ft®) to be stored in the retention pond and the surface area and possible design lengths (<300 ft) assuming it has vertical walls (s8 ft deep).