Laserfiche WebLink
• - Curve Number (CN) <br />The curve number is determined by considering the soil type <br />and ground cover density of the drainage area. An Antecedent <br />Moisture Condition - III (AMC-III) was used to generate <br />conservative runoff volumes in order to account for snowmelt <br />accompanied by rainfalt. The AMC-III condition assumes a <br />greater antecedent moisture condition exists if greater than <br />2.1 inches of rainfall have fallen within the previous five <br />(5) days. Curve numbers representing disturbed and <br />undisturbed conditions are as follows: <br />Disturbed 96 <br />Undisturbed <br />Soil Type B 78 <br />Soil Type C 87 <br />• Soil Type D 91 <br />- Average Curve Number <br />Meighted average curve number determined by areas of disturbed <br />and undisturbed land in the drainage basin. <br />- Rainfall Amount (P) <br />Rainfall depths for the 10-year, 25-year, and 100-year, <br />24-hour duration precipitation events were taken from the <br />Precipitation-Frequency Atlas of the Mestern United States, <br />Yolume 3 - Colorado, (NOAA, 1973). <br />- 10-year. 24-hour rainfall 1.7 inches <br />- 25-year. 24-hour rainfall 2.0 inches <br />- 100-year. 24-hour rainfall 2.5 inches <br />• <br />23-13 <br />