|
<br />Pueblo Flood Hazard Miti"ation Pion
<br />
<br />.. ... . ..... - --- - ,. - - ,. ---. --
<br />.:',."::::'.:,,..:...:::::-.::.:..-:....,'..::.:-:.::.:.:.::.:.:.;..:....':.:.:..:::.;.:-:-,;.;.-:.:.;..;:..:::-.:-:--;,.;.-.:,:-:;:'...-::..:.;:.......;..';.;'......
<br />, ,Durjn'g a ~ery iar'ge flood (~bouta 500..'
<br />
<br />,~:~;!!t::/:?;;t::/::;:;nf;;;::: ,.'
<br />
<br />, Just 3ft/see eoinhjned wjth depihsof3 '
<br />ftor ~ore are geJieraiiy considered
<br />hazardous to life as well as to ' '
<br />property, "
<br />Water flowing in excess of 4ft/see is ,
<br />
<br />'. .:~=::,; :LZZ;:::~:::;:::1;:;;a:jj .',
<br />
<br />, andembatikment fill, aroimdbridge ·
<br />
<br />
<br />;;-.
<br />
<br />,saturaiioneffedsoffloodjng of long .
<br />, durtition Can 'effectively weaken bridge
<br />
<br />· .::::::ZJ;;~r:::/::::::~:::;;;;:;...
<br />
<br />faiL
<br />
<br />Flood Types: A river basin is fed by a
<br />network of stream ehannels that eonvey the
<br />normal flow of water from smaller
<br />watersheds contained within the basin,
<br />Flooding results when the flow of water
<br />becomes greater than the earrying capaeity
<br />of the individual stream channel. Rate of
<br />rise, peak diseharge (magnitude), and
<br />duration of flooding are all physieal features
<br />and weather eonditions which eontribute to
<br />the characteristies of the water in the river
<br />system, The following deseribe sources of
<br />riverine floods:
<br />
<br />Snowmelt floods- Snowmelt flooding
<br />typically oeeurs May through Jooe,
<br />Generally this oecurs when there are warm
<br />spring temperatures ereating a fast snowmelt
<br />and/or a combination of spring runoff and
<br />rainfall over the affected watershed, Serious
<br />flooding ean result when a heavy spring rain
<br />aeeompanies a snowmelt in May and Jooe,
<br />
<br />Flash floods- These floods result from
<br />intense summer thunderstorms, This flood
<br />event is charaeterized by an intense
<br />cloudburst, a sudden rise in stream level,
<br />short duration, and little or no warning,
<br />Typieally the flash flood season in Pueblo
<br />stretehes between May to September,
<br />
<br />General rain floods- These floods are.caused
<br />by general rainfall events that oeeur over a
<br />wide geographie area for several days,
<br />totally saturating the shallow soils, These
<br />floods are characterized by a slow, steady
<br />rise in the stream level and a peak diseharge
<br />of long duration, Beeause of the slow rate of
<br />stream rising there is usually time available
<br />for warning, The Midwest floods of 1993,
<br />and more recently, the Georgia floods of
<br />1994 are good examples of this kind of
<br />flooding,
<br />
<br />Dam failure- Floods caused from dam
<br />failures are rare, but when they oecur they
<br />can be devastating. Pueblo Dam, a massive '
<br />buttress-head and earthfill dam, is designed
<br />to handle at least a I DO-year flood, If Pueblo
<br />Dam broke (considering the worst-ease
<br />seenario of water level at full eapaeity and a
<br />eomplete breach), the water would inundate
<br />nearly all of the downtown area of Pueblo,
<br />More specifically, this inoodation zone
<br />would primarily include the area from the
<br />State Hospital in Pueblo south to the
<br />Arkansas River, and would have minor
<br />impacts out east near Avondale. Inoodation
<br />
<br />8
<br />
|