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1. Discharge - Drainage area relationships Flood Insurance Study (FIS), Orange County. <br />Table 7: discharge of East Garden Grove Wintersburg Channel at Euclid St. <br />Showed: <br />→Drainage area: 7 sq miles. <br />→Drainage: 1,600 cfs. <br />2. Flood zone = Zone A <br />3. Bench mark = 65.336', SA-313-83 NAVD88. <br />4. East Garden Grove Wintersburg channel (C0-5) at Euclid St. had 10' with & 11.5' high slope 1.5:1. <br />5. Normal depth calculation: <br />Q = 1.49/n x A x R2/3 x S1/2 <br />n = 0.03 <br />S = 0.0283 <br />Assume water level at 9' high from the bottom of channel at Elev. 63.50. <br />Calculate Q: A = (13.50 + 13.50 + 12 + 12) x 9/2 = 229.5 sf. <br />P = 16.22' + 16.22' +12 = 44.44 ft. <br />R = A/P = 229.5/44.44 → R2/3 = 3. <br />With S = 0.0283 → S1/2 = 0.053. <br />Qcal = (1.49/0.03) x 229.5 x 3 x 0.053 = 1812 cfs. <br />Qcal > Q100 = 1600 cfs → OK. <br />→ Water level for 100 year flood under elevation of 63.5 for safety. <br />- Add 3.04 ft above flood elevation → FF = 66.54 ft (ADU). <br />Page 5 of 8