FLOOD00950

• County: Statewide
• Title: Rock Riprap Design for Protection of Stream Channels near Highway Structures volume 2
• Date: 1/1/1986
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

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[he.-> need t~.i e"ial~L1te the v3rious pc."'')l~edllres bei.ng Il,;ed tu de~,ign rock rip-
rap ~,jS h~e!1 indiC:lte'l by t.he diverse resil1t.s thdt ;n,lY fJP ()hL.ll.lled depending on
the p:-:::;cedll:::e llSP'., .Eld a~sumptions CO(lc",=,-'ntng hydLIUll(' cInd g'.:'I)morphic condi-
tions ~t ~ site. Failure at d site is llsually attriblltt~\i tll excessive hydraulic
forces .1ct.i~lg on the bank and c3using di.:;pLacement of t.he str)nes thdt comprise
the rip-c.:lp (fig. 1). HOw'ever, other LlctOl:'S, sllch ::lS impLope!:' gradation or
placement of st.one, inadequate assessment of probable mOLpho10gic changes, or
faiL!~re (): ~he o:ciginai bank m.1terial may cOflcribute to the Liprap failure.

>1ethods ::lvaildble to protect high\..;ay stl~uctllres from stceamflm.... hazards
incL i::'.~ ,lemor-lng. retards, .:lnd spurs. :'\nnoring is che surL3cing or a channel
bed ",.... j;.Ell<S. l);-:- an embankment sLope; :c,=t.lrds are 3. permt':.1ble or- impermeable
struc:'ure ~n :1 channel to deflect fl.Jv.'; .1Ild :.:;purs 3rc Linear structures
projec:i.rl~ into a channel to induce depositi.on along the bank.. .-\ description of
these (and atheL) pr0tective measures (countermea~ures) dnd .1n evaluation of
their performance at various field installations is given in a report by Brice
and Blodgett (1978)"

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FIGl"RE I. Erosion ('of rnL"k riprap on left bank of Pin ole Creek at Pinole, California" following flood of
.Jar1lli.lr~' .t. 19,~:2. :\( Ite de;)l )~iti()n of displa<:ed riprnp in channel bed (photog-raphed ~Iarch 1982L