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I I I I I I I I I I I I I I I I I I I 7 - FUTURE FLOODS - bank of the creek in this reach. Some green houses and accessory buildings immediately east of the Burlington Ditch would be inundated. Several other structures in the flood plain west of Dahlia would be inundated. Small amounts of water will flow to the north under the I-270 bridges at Brighton Boulevard and Albion Street. No attempt has been made to define the flow paths of this water. Between Ivy Street (extended) and Quebec Street, approximately 60 industrial type buildings are subject to sheet or shallow flooding. Sheet flooding is defined as overbank flow of a channel which cannot re-enter the channel except at a point downstream from where it overflowed. The water is generally less than one foot in depth. In the reach from Quebec Street to Havana Street, (Sheets 14 to 27) the major flood plain development consists of I-70 and two north-south runways at Stapleton International Airport. A large amount of essentially undeveloped airport land is inundated by either overbank flooding or sheet flooding. Here again, small amounts of water will flow to the north over I-70. No attempt has been made to define the flow paths for this water. Havana Street will be inundated to a depth of approximately 8.0 feet and the Denver County jail would be surrounded by flood water. The reach from Havana Street to Chambers Road (Sheets 27 to 43) contains most of the residential development in the flood plain. Several hundred homes are subject to either overbank flooding or sheet flooding. Also, in this reach, flood waters sheet flow across Smith Road to the north. No attempt has been made to define areas subject to sheet flow north of Smith Road. The reach from Chambers Road to Colfax Avenue (Sheets 43 to 52) contains a major mobile home park which would be subject to sheet flow during the 100- year flood. The mobile homes are a potential source of debris which could be Flood Frequen~ and Discharge Floods of the same magnitude as those that have occurred in the past can recur in the future, and even larger floods are possible. The discussion of future floods in this report includes the hydrology, and discharges for the 2, 5, 10, 25, 50, 100 and 500-year floods for present and two future basin conditions; however, only the 100-year flood for future basin population conditions (600,000 population forecast) is displayed on the Flood Hazard Area Delineation maps and described in the Flood Plain Reference Data Table (Table 3). The 100-year flood is a type of flood, including the water surface elevation and territorial occupation thereof, which can be expected to occur at any time in a given area based upon recorded historical precipitation and other valid data, but with an average statistical one percent chance of being equaled or exceeded during any one year. The 500-year flood would be larger and occur less frequently than the 100-year flood. The 500-year flood is a rare event, but could reasonably be expected to occur in the future. Floods larger than the 500-year are also possible, but the probability of their occurrence becomes increasingly remote. Flooded Areas The 100-year water surface profiles and flood plain limits are shown on the attached Flood Hazard Area Delineation. maps. The computed 100-year flood eleva- tions for each cross section utilized in the hydraulic computations are listed in Table 3. Cross section locations are shown on the maps. A discussion of the extent of flooding is discussed in the (ollowing paragraphs. In the reach from the Burlington Ditch to Quebec Street, flood plain development is mainly cOTllTlE!rcia1 and industrial. I-270 parallels the north