FLOOD11628 (2) - Laserfiche WebLink

Home Browse Search

A le2t-bank tributary at abuut 7,640 feet with an estimated drainage aiea af about 0.4 aquare~mile, does not have any alluvial fan or uther evidence of sediment ts•an3p~rt. The channel is about 2 feet wide and lesa than a foot deep. Rocks are completely coverzd with ~rasa, vegetation, moas, or lichen ta within 0.5 feet of the streambed. The recent discharge is about 20~cubic feet per second. Ptote that ma:cimum.water level can be elightly higher than the moss and lichen level before abraiding them. There is no flood debris lodged upatream from obstructions. 'Chis lack of flood evidence indicates that tl~ws have not e:cceeded the eroaion threshold discharge af 200 t~ 300 cubic feet per second for 10P~ years ~r more. Ruxton Creek, bath upstream and down3tream from this tributary, has a width ~f 3 feet and graes, moss, an~ lichen ~row• to within 0.5 toot of the atreambed. There are no tree scars ~r flood ~ebris, ~r ev~jence of signisicant sediment movement. This would indicate that recent throu~h maximum flowe in the last hundred or more }iears have i~een na larger than about 3~~ cubic feet per second which is consistent with maximum snowmelt runoff in Colorado. At Artist Glen tributary at an elevation of 8,000 feet. with an estimated drainage area of 0,8 square miles, the channel was very similar to the 7,640 foo~ tributary; the channel width is 2 feet. Recent peak discharges ha"ve been about 20 cubic feet per secorid. This lack o~ Yl~~d evidence indicates that flows have not exc~eded the erosian threshold discharge of 200 to 300 cubic feet per second for 10fl years or more. The canyon walls are very steep and have minimal vegetation on the slope, however there is no noticeable rill or gully erosion. ' Because of the location of the Pike's Peak cog railway Which follows the Ruxton Creek drainage to ~ust above Ruxton Par1: at an elevation of 9,200 feet, personnel from the railroad may b~ able to provide some information on the amount and frequency of ma~ntenance associated with water runoff. Many tributaries flow under the railroad and the station in Manitou Springs is located immediately n?xt to the low water channel. The creek is channeled into a 5 foot diameter culvert under the station. Any floWS exceeding the capacity of the culvert (probably less than 200 cubic feet per second) would £low throught the maintenance buildings. If flows frequent:Ly exceed about 200 cubicifeet per second (the flood insurance report tndicates the 10 year flood is 2, 540 cubic feet per second), the bui:lding and buildirigs along Ruxton Avenue would be fiooded almost yea~ly. Has this been the case? Fountain Creek and tributa_r_ies upstream from Manitou Spr:inqs The drainage area of Fountain Creek upstream irom Manitou Springs is 71 square miles. Placement of State Highway 24 in the Fountain Cieek canyon upstream to Cascade disturbed, to an unknown am~unt, and preclude paleohydrologic investigations, particularly of maximum floods. Channel dimensions and deposits probably are representative og recent channel forming flows. Therefore emphasis was ,placed on tributary investigations. q