FLOOD06148

• County: Ouray
• Community: Ouray County
• Stream Name: Uncompahgre River
• Basin: Gunnison
• Title: Hydrology Report Floodplain Information Study Uncompahgre River
• Date: 8/1/1977
• Prepared For: Ouray County
• Prepared By: Neil Grigg
• Floodplain - Doc Type: Floodplain Report/Masterplan

precipitous slopes followed by 17,000' steep channel (about 25%).
Esti~nte char1nel travel time 3t 3-10 fps (30-35 minutes). Addi-
tional overlnnd flow time estimated at 10-15 minlltes. Te = 45
mL1ut2s.

2. CN = 75 (all cases).

3. 24-Hour Precipitation (Reference 7)

T 10
50
100

Cc:sc2de \''J ,., Portland 'A /~ 7
c.A--'
Cl'eek " Creek M~7 ;,
/, ~'_--' '!I
.'.=1.29 5;"";1 .\=7.82 .
---------- ,)~
l\X\ _ r JC: 0.,7..':; i I
no '7 590 ,..
I ~ S('6 I OJ (..0 5-
~80 / ') 1050 - IIJ1e
7,
606 / 0~,\r; ~ I;>;' 13 25 ,.-- /.0" 7 '[ (,77

10 year 2.3"
SO year 3.0"
100 year 3.35"

4. Runo ff (from Table 2-1, TR 55 and CN= 7 5)
10 year 0.54"V
50 year 0.96" I"
100 year 1. 21':';
\.1.0
5. Peak Discharge Per Square :-li 1 e

Frcm Figure 5-2, IR 55 or Fisure S-l (Ref. 8)
./
q = 388 cfs/s.m./inch
p

5. De~k Runoff Calculations (q = qp AQ)

~~2rall Analysi~ and ~25ults

Tt -~2S stated earlier t~at the act of extrapo12ti~g sparse 2ata to 2sti-
-at2 rare 100 and 500 year floods, especially on sDall basins, is cert2in
~0 21icit consider~~le contro\Crsy. The writer is convinced, after cc~-
?:~ci~g s2~2ra1 SilCh ~~alys2s, th~t ~o exact a~31ytical solution 2xi3tS
~cr t~is problem. _\11 of th~ ~ata ~~st be eVallJ2ted ~ithin r2~50~, t~2n
2:-_.:;:..-:~crillg ljdg-;::en.t ~;.:st be. ,"-ppli.2~ to sel,-~ct a 50:'<..:;::' ion. ~:::s sec::.'.Ju
?~c32~ts the writ~r's selecti:n of a solution ~2S2d ,)n the ~2ta pr2s~nt-
:...: ,::.~j t;,e i~?:?lL::at::.,j:1. of ;-;is ~c:;t ~-:c.0::-:..::nt. It is "::''':'s2d 0:1 ::.'-:e =C'l;.,:]T,.,~-
---5 ri.:1ci?les:

,

c

,

1. ?,Jr ~Arf;er ~LsL:.s t:-:2 \al:..:.es .::;i.-:cn in T1-1 1 iir2 ;~, ~"2.1:y ::-..:re. ::..-.:::l:able
..:.~~d c.reJi':Jle t~an Lhose. in the CJ~'f report al:::'l0;1,;~. the latter a;-?rv,,-1.ch
is attractive to t~e 2xtent that it enables l1S to predict larger 500
~~dr floods, cO~5ist~nt ~ith cbser~atio~s.

.,