Dambo la Shasta

Dambo la Shasta mu 2017

Dambo la Shasta (lotchedwa Kennett Dam lisanamangidwe) ndi damu lokoka miyala ya konkriti kuwoloka Mtsinje wa Sacramento kumpoto kwa California ku United States. Pamtunda wokwana mamita 183, ndi damu lachisanu ndi chitatu lalitali kwambiri ku United States. Ili kumpoto chakumpoto kwa Sacramento Valley, Dambo la Shasta limapanga Nyanja ya Shasta kuti isungire madzi kwa nthawi yayitali, kuwongolera kusefukira kwamadzi, magetsi ndi kuteteza chitetezo chamadzi amchere. Dziwe lalikulu kwambiri m'bomalo, Shasta Lake limatha kukhala ndi ma 5,600 GL.

Akuganiziridwa koyambirira kwa 1919 ngati kuyesetsa kusunga, kuwongolera, kusunga, ndi kugawira madzi ku Central Valley, dera lalikulu laulimi ku California, Shasta adavomerezedwa koyamba m'ma 1930 ngati boma. Komabe, zomangira sizinagulitsidwe chifukwa cha kuyambika kwachuma chachikulu ndipo Shasta adasamutsidwa kupita ku feduro Bureau of Reclamation ngati ntchito yaboma. Ntchito yomanga idayamba mwakhama mu 1937 moyang'aniridwa ndi Chief Injiniya a Frank Crowe. Pakumanga kwake, dziwe limapereka ntchito zikwi zambiri zofunika; adamaliza miyezi makumi awiri mphambu zisanu ndi chimodzi isanakwane mu 1945. Atamalizidwa, dziwe linali lachiwiri kutalika kwambiri ku United States pambuyo pa Hoover ndipo amadziwika kuti ndi amodzi mwamipangidwe yayikulu kwambiri ya uinjiniya.

Ngakhale isanaperekedwe, Shasta Dam idagwira gawo lofunikira pa Nkhondo Yachiwiri Yapadziko Lonse yopereka magetsi ku mafakitale aku California, ndipo ikadali ndi gawo lofunikira pakuwongolera magwero amadzi aboma masiku ano. Komabe, zasintha kwambiri zachilengedwe ndi zachilengedwe za Mtsinje wa Sacramento ndikusefukira kwa mafuko opatulika a Amwenye Achimereka. M'zaka zaposachedwa, pakhala kutsutsana pazokweza dziwe kapena ayi kuti alolere kusungitsa madzi ndikupanga magetsi, lingaliro lomwe otsutsana ndi mafuko ndi akatswiri azachilengedwe adakumana nalo chifukwa chakusokonekera kwamadzi kuchokera mumtsinje womwe nsomba zomwe zatsala pang'ono kutha kuphatikizapo mitundu ya nsomba.

Malingaliro oyambilira

Chakumapeto kwa zaka za zana la 19, Central Valley ndiye malo opitilira anthu ambiri osamukira ku California ochokera kum'mawa kwa United States. Dera lachigwachi ankalilakalaka kulima chifukwa cha dothi lake lachonde, nyengo yabwino, malo ake abwino, ndi madzi ambiri. Mtsinje wa Sacramento umadutsa chakumwera kudutsa gawo lachitatu lakumpoto la chigwa, chotchedwa Sacramento Valley, kwa mtunda wa makilomita 640 usanalowe m'chigwa chachikulu, Sacramento-San Joaquin Delta, ndipo pamapeto pake Pacific Ocean. Pofika kumapeto kwa zaka za m'ma 1800, zigawo zonse za m'chigwa ndi Delta zidalimidwa kwambiri ndi mbewu zosiyanasiyana kuphatikiza tirigu, thonje, mpunga, zipatso za zipatso, ndi mavwende.

Malo otsetsereka otsika a Sacramento Valley amawapangitsa kukhala osavuta kusefukira m'nyengo yozizira; Komanso, kuthirira kumafunika nthawi yachilimwe chifukwa chamvula yamvula yambiri. Ngakhale kuti Mtsinje wa Sacramento umatulutsa madzi okwana maekala 22,600 miliyoni chaka chilichonse, madziwo amayenda kwambiri nthawi yamkuntho m'nyengo yozizira komanso nyengo yachisanu yomwe imasungunuka. Momwe ulimi umakulirakulira, mitsinje yotsika idatsika ngakhale kutsika, zomwe zidapangitsa kuti madzi amchere alowe kuchokera ku San Francisco Bay kupita ku Delta. Izi zidadzetsa kusowa kwa madzi m'minda ya Delta, ndipo zidadzetsa teredo (nyongolotsi yamadzi amchere) pakati pa 1919 ndi 1924 yomwe idawononga ma piers ndi zombo ku Suisun Bay.

Pofuna kuthana ndi vuto la mchere, nzika zakomweko zidaganizira zomanga mafunde pakamwa pa Suisun Bay, ntchito yomwe sichidachitike. Mu 1919 yankho lina linabwera mwa dongosolo la Marshall Plan, lopangidwa ndi Robert Marshall wa United States Geological Survey. Adakonza dziwe lalikulu kuwoloka Mtsinje wa Sacramento kumunsi kwenikweni kwa malo ake ndi Mtsinje wa Pit pafupi ndi tawuni yamigodi yamkuwa ya Kennett, mamailosi mazana angapo kumpoto kwa Delta. Damu limasungira madzi kuti atuluke m'miyezi youma pomwe Delta inali pachiwopsezo chachikulu kulowa m'madzi amchere, ndikupindulitsanso kuwongolera kusefukira kwamadzi m'nyengo yozizira. Madzi omwe adatengedwa ndi damu adzawonjezera kuchuluka kwa kuthirira, ku Sacramento Valley ndi San Joaquin Valley kumwera chakumwera, komwe kumalumikizidwa ndi ngalande yayikulu komanso malo osungira madzi.