FLOOD01592 - Laserfiche WebLink

Home Browse Search

""-"7// / ) L/'\ , - , ( r J ! / " "', " \ , , , 0 , , , . '" . , , , , j I ,\ , ~i~hin the ~tudy ~eac~es, the La~e fork nas an average gradient of 0.6% and an avera;e c~annel ~idth of 60 feet. Normal ~ater depths are 2.5 feet. HensonCree",'"i"';hin ltsstudyreacn, has an avera;;e gradient cf 1.2%,dverage w;dth nf 50 fee: a~d average depth of 2 feet (during nor~al f10ws:. Stream sub_itrate consists of large boulders, cobbles and bedrock. Streamside vegetation consists of cottonwoods, willows and similar brush along both streams. Obstructions to floOdflow$ ~itnin the study reach include both natural obstructionssuchaSvegetatiOngrowth,falJentrees, ice jams, etc. and man_made obstructions such as bridges, buildings, fences and roadwayS. These obstructions have a tendency to increase flood elevations upstre am of the obstructions and increase velocity downstream of the obstruction. The stream valley above the Lake Fork study reach is essentially similar to the study reach description (except it has a narrower flood plain). Lake San Cristobal, a natural lake approximately 3.5 miles above Lake City.hasa dampening effect on potential floods such as those occurring from high intensity, short duration rainfall. For long duration spring snowmelt and combination rainfall, however, the effect of the lake on peak floodflows is minimal. The stream valley abQve the Henson Creek study reach is very narrow and steep. Trees and brusn grow out over the cnannel in many areas along this tight valley. High waters could carry great amounts of debris through the ,tudy reac~ a~d acce~tuate the flood elevations. The historical use of the floodplain has been for range, wildlife and resort activities. Land adjacent to the streams is privately owned. These areas have good plant cover and support meadow vegetation, willows and cottonwood. Small dreas within the floodplain are flooded annually and support little or no vegetation. rhegrowth of Lake City in rl'cent years has forced greater development in the flood plain. With this increased encroachment of development In the 1'lood plQin, tho: fluw hutare t;; troc cc~~~~:ty is incr'?d;"~ and will continue in the future unless adequate measures are adooted to keep the development outside the flood hazard areas. I ' , e I , , , ! , ! PLA'Lc1a JF S'LUDY ~EACHES Fork of Gunnison River and Henson Creek T. :., 9 to