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P~oject Flood dlsc~~ge5 at spacilic locations 310n~ each ~trea~ can be found in table 7 also. Hazards of Great Floods The effects of the Intermediate Regional and Standard Project Floods were analyzed to dete~mlne the flood potential for each st~eam. The analysis was mllde usl ng bridge and va Iley cross sections ..hlch ..ere su~veyed In 1970. The ..ater surface prof lies were determined usIng back..ater computatIons employing the Standa~d 'I Step ~eThod. The head losses- at The b~ldge and la~ge culve~ts were compUTed using data In "Hydraul !cs of Bridge Waterw"ys" published by the U.S. Department of Commerce. Wel~ and submerged weir flow waS used ..ith the above wheneve~ water overtopped any pOrtion of the roadways. The small culverts were considered blockocl by debris, or carrying only a small portion of the large floods making theIr effect on the profile Insignificant. The extent of floodIng Is shown on the "Flooded Area" plates for each stream (see Index ""'P plllte I). Flood outtlnes were determined from the surveyed cross sections and U. S. r~logical Survey quadrangle maps to show the general areas subject to flooding. Fo~ any specific siTuation. ..here accuracy 15 needed it ..III be necessary to take the approprIate flood elevation from the profiles and locaTe by su~v~y ils corr~sponding ground elev~~lon en ~hc flood Water surf<lc6proflles for the intermediate Rcglor.l,li and Stand"rd Project Floods are shown on the "Profile" plates which follow the "Flooded Area" plates for each stream, Theprofllessno" the depths of flooding In the channel and the elevation of the ..ater surfaces ove~ the adjacenT flood plain. Where Dutch Creek enters The South Platte River flood plain the lands adjacent to Dutch C~eek slope away from the stream banks. Stream overflows are not confined "Ithln stream ~nks and ..II! not correspond to the channel profile. but"ill generally act dS "sheet flow" runoff..lthanundulatlng "ate~ surfdce. For This reason computed ~ter surfaces at the stream location cannot be projecTed over the flood plain in this area. The "Cross Section" plates show the channel and va!ley ground-line and the depths of ove~tylng flooding. Refe~ence points have been p~ovlded to locate flood elevations at intervals along the streams. The reference points coincide "ith the location of the surveyed cross sections whiCh were used to make the study. The locations of the reference poInts areshollnon both the "Flooded Area" platesandthe"Profile"plafes . A tabuJation of reference point data is provided intablesfollolling the text, The tabu let Ions shOll The elevatIons of the STreambed, the Intermediate Regional Flood and Standard Project Flood. A dIrectIonal bedrlng Is also provided to shOll the orientation of the cross section throuQh the reference point, Greater Floods Floods even larger than the Standard Project Flood are possIble, but The combination of factors to produce such floods would be e><trwnely rare, Such floods ere not furTher dIscussed In This report, alThough they should not be ove~looked where absoluTe safeTy from flooding Is a requirement. plain. 1/ See Glossa~y of Terms " "