|
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />II
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />I
<br />
<br />TABLE 5
<br />WHITE RIVER CROSS-SECTION IDENTIFICATION
<br />
<br />
<br />
<br />",.,.,.'.'.'d-.-'-'.-.".-.-__'.-.-,
<br />'"..,-',.,"',-',.,-"".,"','"","',",',',,.,.,'",,',
<br />.'.Ii?_*'ltIQ1.I(
<br /><j}l'l!LlXll;i,.,'.,'.....'..,
<br />.,--"-",.,.,--..-.-.-.-.-,-,,,.'.-.----.--.--,.
<br />.n, ltl'tl'Wl>>
<br />. ."."..",.".".
<br />
<br />',', ',...."."........"....,. --.'
<br />",',.".,'".,.,.,.--..,..."..----,',,',,',",,',".....,',""."
<br />... ... ... " .--..... . . ... .......
<br />.....,"',',.."........"."..--,...-----,',','
<br />...]j,lQ'WvAtllfl5S{OES)....((
<br />,Il~jQP1Yi((
<br />..._qilm~
<br />
<br />I
<br />2
<br />3
<br />4
<br />5
<br />6
<br />7
<br />
<br />6934, 8133 (WI) Z-Z' 3
<br />9565, 12501 (W2) A-A' I
<br />10137, 13508 (W3) NONE CANYON REACH
<br />11007, 15079 (W4) B-B' 1
<br />12051, 17021 (W7) D-D'. I
<br />12051, 17021 (W7) E-E' 2 (FROM B-B')
<br />13500, 20000 (W9) NONE DETAILED STUDY
<br /> ALREADY PERFORMED
<br />13500, 20000 (W9) FA-FA' 3
<br />13500, 20000 (W9) NONE CANYON REACH
<br />14539,21873 (WI0) F-F' 4
<br />
<br />CALCULATED
<br />N/A
<br />FEMA STUDY
<br />
<br />CALCULATED
<br />CALCULATED
<br />N/A
<br />CALCULATED
<br />CALCULATED
<br />CALCULATED
<br />FEMA STUDY
<br />
<br />8
<br />9
<br />10
<br />
<br />· Map-derived cross-section C-C' was prepared, hut it was not used. It was omitted because the field-surveyed
<br />cross-section, D-D', located in the same reach, better represents that reach.
<br />
<br />4.4 Comoutinl! Flood Deoths
<br />
<br />Flood depths were calculated at each cross-section through a computer program (QANY) which
<br />uses Manning's equation. The input parameters for the calculation of flow included: x and y
<br />coordinates for points on the cross-section, Manning's 'n' values (ranging from 0.03 to 0.032 for
<br />the channel and 0.045 to 0.065 for the overbank) (Reference 7), the channel slope (interpreted
<br />from USGS quadrangle maps), and depth values. The program calculated flow and velocity
<br />values for each depth value entered. The target flow values were those values established in
<br />Section 3.0 and shown on Table 3. Rating curves were established from the calculated depths.
<br />From the rating curves 50-year and 100-year flood elevations were established at each location.
<br />
<br />In performing the depth calculations the flow on the river the day of the survey was obtained
<br />from the USOS and subtracted from the established 50-year and 100-year flows for each
<br />particular hydrologic point. The depth of water on the day of the survey was estimated and
<br />added to the flood depth calculations to obtain the true flood depths shown in Table 6. The
<br />methodology used for computing flood depths at the cross-sections is similar to accepted
<br />methodologies used by state and federal agencies in performing detailed analyses, except that
<br />there is no balancing of energy from one cross-section to the next.
<br />
<br />18
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