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3. Consider the following situation and answer the subsequent questions to the best of your engineering ability and judgment. a. There are two Schultz Creek watersheds, East and West. The East drains into unincorporated communities east of Flagstaff, and the West drains into the City of Flagstaff itself. The key point about unincorporated' is that this means these residents did not live in a city or town, and for some infrastructure aspects like storm drainage, there were no requirements or regulations. Prior to 2010 both of these watersheds were heavily forested and due to almost a hundred years of fire suppression instead of fire management, both watersheds had accumulated thick, water-absorbing masses of pine needles and decomposed pine needles on the forest floor. This prevented the watersheds from 'delivering' runoff to its streams in normal years because all of the precipitation was stored in the pine needle layers, sometimes referred to as 'duff'. Only in heavy snow and rain years, about once every 5-7 years, would the streams flow, instead of every one or two years. ii In 2010 wildfires burned much of the higher elevations of the heavily wooded East Schultz Creek watershed, which was followed by heavy rains (15-yr precipitation event), which produced heavy flooding, debris flows, extensive erosion and gullying, resulting in loss of one life and over a hundred million dollars in damages. The change in hydrologic soil group coverage of the watershed became: 40% HSG D, 35% HSG C, 20% HSG B, and 5% HSG A. ANSWER NEEDED! Calculate the new curve number for this watershed. Show work. Another weighted average problem. 3. Consider the following situation and answer the subsequent questions to the best of your engineering ability and judgment. a. There are two Schultz Creek watersheds, East and West. The East drains into unincorporated communities east of Flagstaff, and the West drains into the City of Flagstaff itself. The key point about unincorporated' is that this means these residents did not live in a city or town, and for some infrastructure aspects like storm drainage, there were no requirements or regulations. Prior to 2010 both of these watersheds were heavily forested and due to almost a hundred years of fire suppression instead of fire management, both watersheds had accumulated thick, water-absorbing masses of pine needles and decomposed pine needles on the forest floor. This prevented the watersheds from 'delivering' runoff to its streams in normal years because all of the precipitation was stored in the pine needle layers, sometimes referred to as 'duff'. Only in heavy snow and rain years, about once every 5-7 years, would the streams flow, instead of every one or two years. ii In 2010 wildfires burned much of the higher elevations of the heavily wooded East Schultz Creek watershed, which was followed by heavy rains (15-yr precipitation event), which produced heavy flooding, debris flows, extensive erosion and gullying, resulting in loss of one life and over a hundred million dollars in damages. The change in hydrologic soil group coverage of the watershed became: 40% HSG D, 35% HSG C, 20% HSG B, and 5% HSG A. ANSWER NEEDED! Calculate the new curve number for this watershed. Show work. Another weighted average

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