<br />....
<br />
<br />,,~to<,
<br />
<br />...it'>.a.dditional desttuctive force.
<br />
<br />Ob6t,uction. caused by debris
<br />
<br />Rio Crande , 209.4 (64.8) 24Q,l 000.9)
<br /> , 52.1 (21.1) 93.6 (37.9)
<br /> 6 ~3.1 (21.5) 76.9 (J1.1l
<br />Subtotal 314.6 (127.4) m (169.9)
<br />Study Area .otal 377.1 ClS2.?> SOI.5 (203.1)
<br />
<br />I
<br />I
<br />
<br />t
<br />t
<br />I
<br />1
<br />
<br />i~~~ brid~~' and culvert!.
<br />
<br />The.e obst'uctions .act .s dams, baCkinq the
<br />
<br />'/]~ ~r
<br />
<br />"pstt""", untit
<br />
<br />,h"ybteak loose,Cllusingasudden surge Of..St1 of
<br />
<br />I
<br />
<br />Flood haurd exhibits fo, the study area are in the Ai>P"ndix fotlowinq
<br />
<br />I
<br />I
<br />
<br />I
<br />
<br />cloqqin~ culvett. and bridges are variable, resulting in a cultitude of flow
<br />,,,ndition" .....iell lIreunpredicuble for anYl\;",en fl<>od,,"enL The pOtential
<br />dIet! of debris dogging are n"t included in the flood profile detet..ina-
<br />
<br />11 One aCre is equal to 0.405 hectares.
<br />
<br />Flood Hazard Kshibit.
<br />
<br />t;ons.
<br />
<br />the teKt of thi. report. Included in the Appendix are: Flood hazard acea
<br />
<br />I
<br />
<br />g
<br />
<br />I'loodwaterflowingathi'?hvelocitiescre.tesd.ngerou.<:ondition..
<br />
<br />map index, flO<>dh.zard ..e....p., flood profiles, typi<:d ".lleycrou-
<br />.ections. .nd t.buhtions for the flood frequency-elevation .nd disch.rge
<br />d.ta. Por uae in deten.ining the flood huard foc .ny particular location,
<br />
<br />I
<br />
<br />"eloclti... exceeding 3 feet pH aecond ..ith depths of 2 feet 0>: ",Ore aCe
<br />
<br />1
<br />
<br />&ener.lly considered haz.rdous. Those condition. would exist at several
<br />loc..tion~ in the study ..rea, especially in tile rivH clla<lnels and depressed
<br />
<br />the flood profilea andtabutar....terial.re as.eOlbledbyr".chnu",bers in
<br />sequential order, I throu~h 6. The follo..in'? are descriptions and suggested
<br />
<br />I
<br />
<br />11
<br />
<br />ar~"s within thl! ftoGd plain.
<br />
<br />\l
<br />
<br />Duration of floodin'? will vary, depending on the se.son in which
<br />
<br />I
<br />
<br />usea of the exhibiu.
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<br />I
<br />
<br />f1oodin'loccurs. In the spdn'?";,e,, the strea"", are hi.,!h with runoff fro..
<br />
<br />Maps
<br />
<br />I
<br />
<br />sno""",lt, coupled with "prinll r"ins, high wat..T could persist for s everal
<br />
<br />For p1annin~ and flood zon" re~ul"tion purposes, the 1000-ye..r flood i.
<br />
<br />I
<br />
<br />1
<br />
<br />days. Durin'l the late su~r ~nths ,,;,en the strea~ ar.. normally 10",
<br />
<br />used Incal1y aR th.. baa.. flood. I....ger flood., aueh as the 500-ye.u Hnod
<br />
<br />.unoff frO<a thundersto.ms will recede in.a few h>>,.....
<br />
<br />a~e aho considered in the p\annin~ and .....na~e"'ent nf flood-prone I\reas.
<br />
<br />I
<br />
<br />1
<br />
<br />Flood Hazard Areas
<br />
<br />J
<br />
<br />The tote! flood hnard area On all teaehes subject to inundation by the
<br />
<br />The 100-y....r ..nd 500-ye..~ .."..nts ar(" outlined on the Flood Il.aurd Are.a M.aps.
<br />In .....ny inst..nc,," the (lOJur Hmit. of th.. 100- and 500-year fh.",ds will
<br />
<br />I
<br />
<br />100-ycar flood under present eonditions is about 371.1 acres C152.7ha l.
<br />
<br />spp"..r "" on.. ;ine on eh.. "'''ps. '('IIi. is due to tile topo~raphlc relief and
<br />
<br />1
<br />
<br />J
<br />
<br />The are.. incr"nes to about 501.5 aeres (203.1 ha) for the 500-y"ar flood.
<br />
<br />sli~ht differenee in elevation bet..e..n the two flood eve..es. It ,,"ould be
<br />noted chn .are:lS sho"", as fIo>>ded on the mapa....y vary "lOre or I".... ..i.th
<br />
<br />I
<br />
<br />The foltowin'ltabulation for areas flooded isby.t1,&dyreaehforcheSnuth
<br />
<br />1
<br />
<br />fork and Rio Grande.
<br />
<br />J
<br />
<br />Rivn
<br />
<br />StudyR....cb
<br />".
<br />
<br />Flood Haza.d
<br />lOO-'{earf'lood
<br />Actea (H..ceares) II
<br />
<br />Area
<br />500-'{..arFlood
<br />Aeres (Heetares)
<br />
<br />presentfieldeonditi.ons. rordecailed i.nfoUlation. HoodeLevations.hould
<br />be deter..i.nedat specifie 10c.tionsandeheeked..ithfi..ldRurveys. The
<br />
<br />tOpO~f"ph;c ~ppin~ WSR obtained Photo~~smmetrienllv frO'l1 ac.ial Dhntn~.,,~hy
<br />
<br />I
<br />
<br />SOuth!'nrk
<br />Rio Grande
<br />
<br />1
<br />
<br />49.0 (I~.II)
<br />1.0 (0.4)
<br />12.5 (5.1)
<br />62.5 (25.3)
<br />13
<br />
<br />57.5
<br />
<br />(23.3)
<br />
<br />flown Jllne 16, 1975.
<br />
<br />I
<br />
<br />,
<br />J
<br />
<br />4.'
<br />19.9
<br />ii:9
<br />
<br />(l.8)
<br />(8.1)
<br />(33.2)
<br />
<br />l'
<br />
<br />Subtotal
<br />
<br />.
<br />
|