|
<br />
<br />SOUTHERN CALIFORNIA FLOOD MANAGEMENT
<br />
<br />Los Angeles County is California's first urban flood
<br />control district. The Los Angeles County Flood
<br />Control District was formed by special legislation in
<br />1915, In coordination with the Corps, it operates one
<br />of the most extensive urban flood control and water
<br />conservation systems in the world. It is administered
<br />by the Los Angeles County Department of Public
<br />Works (DPW) which provides flood management for
<br />1,460 square miles of watersheds in Los Angeles,
<br />San Gabriel and Upper Santa Clara rivers, Ballona
<br />Creek and portions of the Antelope Valley,
<br />
<br />DPW operates and maintains over 143 sediment
<br />entrapment facilities that retain sediment carried by
<br />runoff, 15 flood control and water conservation dams,
<br />29 groundwater recharge facilities, 33 storm water
<br />pumping plants, and 470 miles of channels that
<br />transport runoff from the basin's watersheds, In
<br />addition, the Corps owns and operates five flood
<br />control dams, Supplementing the dams are 2,400
<br />miles of underground storm drains and 97,000
<br />inlets and catch basins.
<br />
<br />This channel in
<br />Los Angeles Cmmt}' is
<br />[Jart of one of the largest
<br />.flood control networks
<br />i/llhe Ivorld.
<br />
<br />The flood control structures were constructed
<br />because flash floods are common in the developed
<br />floodplains in semi-arid southern California. These
<br />floods are smaller, localized and of high intensity,
<br />On New Year's Day in 1934, 40 people died in a
<br />flash flood near Glendale, Four years later, in the
<br />county's most deadly tlood, 113 people died when
<br />water roared through downtown Los Angeles with
<br />
<br />little warning. Floods in 1969 devastated northern
<br />Los Angeles and Ventura counties, killing 90
<br />residents.
<br />
<br />In 1969, the flood control network was found to be
<br />inadequate largely because the continued urbaniza-
<br />tion of Los Angeles exceeded the system's original
<br />design projections, DPW estimated that a 100-year
<br />flood event could inundate 82 square miles, affect
<br />500,000 people and cause up to $2,3 billion in flood
<br />damages,
<br />
<br />Other areas of the state also developed flood con-
<br />trol systems, although none as extensive as those
<br />in Los Angeles and Sacramento. After the Colorado
<br />River was redirected out of its former channel and
<br />created the Salton Sea in 1907, Hoover Dam and a
<br />series of dikes and levees were built to protect the
<br />Imperial Valley, which was a tloodplain in high water
<br />years, In the desert area near the Coachella Valley,
<br />the Coach ell a Valley Water District, formed in 1915,
<br />constructed a series of dikes and levees to protect
<br />the population and agricultural lands from tlash
<br />tloods,
<br />
<br />Hundreds of smaller dams, levees, channels and
<br />bypasses have been built throughout southern
<br />California, including miles of channels on the Santa
<br />Ana River to protect areas of San Bernardino, Riv-
<br />erside and Orange counties to Quail Wash levees
<br />that protect the southern desert town ot Joshua Tree,
<br />
<br />, ""-'-'~,=:~:~1"';: ,;.
<br />
<br />~: ....~ ,-,,-...,..:\~~ ~,.(.~'-oI!"'-'''''' ..... ~ --,. -:;: ~... ~ '<-,.0;.,0,.-. - _..~-;~- .-->,~..- ...'
<br />~ -u..~ ~~~~~~~;~~: J'~ :\~-"~;-::.2"'~.:;c~,~ :~,:-,.. ~' .._.. 'k,'~ i%'~~ ~~_ -:i.~'" ~~'-:~' -,. .~-::~
<br />~h"'_~-:""'.',"",,-1-'"':;.~'_ ,~_:,--~~~~.-."..~,2j~.;;:...,..- '~:.o:"'';'" ~...._ .---. "-t' ~' - -;'J_~ ~ ~-----"""'.~ t."~
<br />~~;!{:'~~~~r~{~{f~~}~~~~~~~~~~_J~<~~~~~
<br />
<br />""-.:.~ -~i - J!III!iIIt._:-"I'-'.-' ,....". .,~~~~_ :..~~~_ro,,;; _..- ~'3..----- "~'-.4
<br />.'~~~.:-~~-:-j~~~ #... -~~~~ ~-..-----;.;' -:':':~__>J--__~:~ _<'_ - ':-~ r:~ '~ ~>~~;:.-~. ~:: --- -~ ~
<br />.-....=.- ',;.r..~~.;:::; '.........:: .~~ '- _oi...-- ~,,~._-,- ~~ -- -':'"f'~:--o...""_ ~"~~ ---s:::.~....... -::::'---i
<br />
<br />~-,~*:;:~":;,.;;:~ ~"--- ~ ~~,:;::~.:,." "_ . - -;.~~ ": ~ ~~: ...~~:~:1
<br />::;"' ~" ...~'~t~ ~~~ .~-= - ~._..;: ~ ~~_ ~~.... _5b ~ s ~
<br />~...... :~""-,......~, '~-<ll.t'~~"" _~ '-= ~ ~ ~ "'=- ~ - - __ ~ _"-:~ . ..~:
<br />~a"""-;: -~ :~'~'=-;i"::: ~::- ~ _ ...: _ ~3- -.. --;: ~ __- ;;; ~. ;;,- !
<br />~,",.. ",-. - '" ~'"I;;:.,~ .... '_-~,
<br />. .-~' -.....'lIt,. -~ - .-,
<br />,', .... .....:.:.~ -,;: --0;",;" ~... -"";''?i -;~~.;
<br />-.,-- - -- ~~~
<br />
|