Gudun ruwa mai tsawo

Gudun Longshore daga halin yanzu na geological tsari ne wanda ya kunshi jigilar turɓaya (layka, silt, pebbles, yashi, shingle, harsashi) tare da bakin teku da ke daidai da bakin tekuna, wanda ya dogara da kusurwar jagorancin raƙuman ruwa. Oblique iska mai shigowa tana matse ruwa a bakin tekun, tana samar da ruwa mai gudana wanda ke motsawa daidai da bakin tekun. Gudun Longshore shine kawai turɓaya da ke motsawa ta hanyar halin yanzu. Wannan motsi na yanzu da na sediment yana faruwa a cikin yankin raƙuman ruwa. An kuma san wannan tsari da drift na bakin teku.https://www.bbc.com/hausa/news/2010/08/100811_nijar_ambaliya

Yankin rairayin bakin teku kuma yana motsawa a irin waɗannan kwanakin iska, saboda ruwa da ruwa a kan rairayin kan rairayar bakin teku. Rashin ruwa yana aikawa da ruwa zuwa gabar teku (swash) a kusurwar da ke da alaƙa da nauyi sannan ya zubar da ruwa madaidaiciya (backwash) a tsaye zuwa gabar. Ta haka ne yashi na rairayin bakin teku na iya motsawa a cikin salon sawtooth da yawa da yawa mita (yadi) a kowace rana. Wannan tsari ana kiransa "rugujewar bakin teku", amma wasu ma'aikata suna ɗaukar shi kawai a matsayin wani ɓangare na "rugucewar bakin teku" saboda motsi na yashi gaba ɗaya a layi daya da bakin teku.

Gudun tsaunuka yana shafar girman sediment da yawa yayin da yake aiki a hanyoyi daban-daban dangane da sediment (misali bambancin da ke cikin tsaunuka masu tsawo daga rairayin bakin teku zuwa na sediments daga rairayar bakin teku). Yankin yana da tasiri sosai ta hanyar ƙarfin oscillatory na raƙuman ruwa, motsi na laka saboda tasirin raƙuman raƙuman ƙasa da shear gado daga halin yanzu. Saboda rairayin bakin teku na shingle sun fi tsayi fiye da na yashi, masu fashewa suna iya zama, suna haifar da mafi yawan jigilar jiragen ruwa a cikin yankin swash, saboda rashin tsawo na yankin raƙuman ruwa.

 Ci gaban ka'idojin drift na dogon lokaci 

Ma'anar tsalle-tsalle mai tsawo ko jigilar turɓaya a layi daya zuwa bakin teku ta hanyar aikin raƙuman ruwa ya samo asali sosai tare da lokaci. Ana iya gano abubuwan da suka faru na farko da suka shafi motsi na sediment zuwa al'ummomin bakin teku, amma fahimtar kimiyya ta wannan ta fara bayyana a cikin ƙarni na 19 da farkon ƙarni na 20. Duk da yake irin wannan fahimta ta farko ba daidai ba ne, wannan juyin halitta ya karfafa fahimtar da ke faruwa a kan iyakar tekun. Fahimtar hanyoyin bakin teku ya ci gaba da canzawa ta hanyar ci gaba da ci gaba da yawa da suka fara shekaru da yawa da yawa da dama.

 Abubuwan da aka gani na farko 
An san rushewar bakin teku da jigilar turɓaya a zamanin d ̄ a, galibi a waɗancan sassan duniya inda canje-canje masu ban mamaki na bakin teku ke faruwa. Koyaya, waɗannan abubuwan lura na farko sun kasance baƙo. Masu kamun kifi, masu aikin jirgin ruwa da mazauna yankin za su lura cewa yashi da dutse sun yi kama da "tafiya" a kan rairayin bakin teku; duk da haka ba su fahimci injiniyoyi ba. Saboda ilimin kimiyya na gaba ɗaya, wannan abu ne mai ban sha'awa amma ba a fahimta ba.

 Karni na 19: Nazarin kimiyya na farko 
Binciken tsari game da matakai na bakin teku, gami da wadanda ke da alhakin yunkurin bakin teku, ya fara ne a tsakiyar shekarun 1800 lokacin da masana kimiyya suka yi ƙoƙarin bayyana matakai na motsi a bakin teku. Daga cikin na farko daga cikin irin waɗannan ra'ayoyin sune waɗanda injiniyan Faransa, Jean-Baptiste Fourier, da masanin ilimin ƙasa na Burtaniya, Robert Mallet suka gabatar. Sun yi nazarin aikin raƙuman ruwa da jigilar turɓaya; duk da haka, a wannan lokacin, ba a riga an kirkiro kalmar nan "longshore drift" ba. Maimakon haka, babban abin da aka mayar da hankali shi ne fahimtar matakai na raƙuman ruwa da tasirin su akan sake farfadowa da motsi na yashi da duwatsu. Batun yana da mahimmanci saboda ya taimaka wajen bayyana siffofin yanayin kowane bakin teku. Koyaya, yayin da aka rufe abubuwa da yawa, ba a fahimci cikakken mahimmancin irin waɗannan hanyoyin ba.

 Karni na 20: an bayyana yunkurin doguwar teku 
A farkon shekarun karni na 20, tsalle-tsalle na dogon lokaci ya zama mafi kyau a cikin bayanin ta hanyar masu nazarin teku da injiniyoyin bakin teku. Sun fahimci cewa kusurwar raƙuman ruwa zuwa gabar teku tana da mahimmanci ga jigilar turɓaya. Wannan ya haifar da ci gaba a cikin manufar "rashin ruwa mai zurfi," wanda hakan ke jigilar turɓaya a bakin tekun. Wadannan raƙuman ruwa sun zama sanannun a matsayin babban wakili na doguwar teku. Wani muhimmin ra'ayi wanda ya fito a wannan ƙarni shine na rairayin bakin teku. Ya bayyana yadda rairayin bakin teku ke samuwa sakamakon iska da raƙuman ruwa kuma a gefe ɗaya na rairayin rairayin kan teku yana faruwa, yayin da a wancan gefen, rushewa yana faruwa. Duk da yake injiniyoyi suna zama mafi bayyane, dangantakar sojojin da ke wasa har yanzu sun kasance matsala ga waɗanda ke ƙoƙarin sarrafa bakin teku.

 Bayani na gaba ɗaya 

 Tsarin tsalle-tsalle na dogon lokaci 
Ƙididdiga da yawa suna la'akari da abubuwan da ke haifar da tsalle-tsalle. Wadannan tsari sune:

 Tsarin Bijker (1967, 1971) 
 Tsarin Engelund da Hansen (1967) 
 Tsarin Ackers da White (1973) 
 Tsarin Bailard da Inman (1981) 
 Tsarin Van Rijn (1984) 
 Tsarin Watanabe (1992) 

Wadannan tsari suna ba da ra'ayi daban-daban game da matakai da ke haifar da tsalle-tsalle. Abubuwan da aka fi la'akari da su a cikin waɗannan tsari sune:

 Jirgin da An dakatar da shi da kuma jigilar kaya
 Raƙuman ruwa, misali, fashewa da rashin fashewa
 Rashin da raƙuman ruwa ke yi ko kwarara da ke da alaƙa da raƙuma.

 Abubuwan da ke tattare da canjin bakin teku 
Gudun bakin teku yana taka muhimmiyar rawa a cikin juyin halitta na bakin teku, kamar dai akwai ɗan canji na wadatar sediment, Hanyar iska, ko duk wani tasirin bakin teku na iya canzawa sosai, yana shafar kafawa da juyin halitta ya zama tsarin rairayin bakin teku ko bayanin martaba. Wadannan canje-canje ba sa faruwa saboda wani abu a cikin tsarin bakin teku, a zahiri akwai canje-canje da yawa waɗanda zasu iya faruwa a cikin tsarin gabar teku wanda zai iya shafar rarraba da tasirin doguwar teku. Wasu daga cikin wadannan sune:

 Canje-canje na yanayin ƙasa, misali rushewa, canje-canje na baya da fitowar tuddai.
 Canji a cikin dakarun hydrodynamic, misali canji a cikin raƙuman ruwa a cikin yankin da ke kusa da bakin teku.
 Canji zuwa tasirin hydrodynamic, misali tasirin sabbin hanyoyin ruwa da deltas akan drift.
 Canje-canje na kasafin kuɗi, misali sauyawar bakin teku daga drift zuwa daidaitawa, gajiyawar tushen sediment.
 Shigawar mutane, misali kariya ta dutse, groynes, raguwar ruwa.

 Kudin da aka yi amfani da shi 
Kasafin kudin sediment yana la'akari da tushen sediment da nutsewa a cikin tsarin. Wannan laka na iya fitowa daga kowane tushe tare da misalai na tushe da sinks wanda ya kunshi:

 Koguna
 Lagoons
 Rashin maɓuɓɓugar ƙasa
 Tushen wucin gadi misali abinci
 Rashin ruwa na wucin gadi misali hakar ma'adinai / cirewa
 Sufuri na waje
 Sanyawa a bakin teku
 Koguna a cikin ƙasar

Wannan turɓaya sai ya shiga tsarin bakin teku kuma ana jigilar shi ta hanyar doguwar teku. Misali mai kyau na kasafin kuɗi da tsalle-tsalle na dogon lokaci da ke aiki tare a cikin tsarin bakin teku shine ƙwanƙwasawar ruwa, wanda ke adana yashi wanda aka ɗauka ta hanyar jigilar bakin teku. Kazalika da adana yashi waɗannan tsarin na iya canja wuri ko ta hanyar wuce yashi zuwa wasu tsarin rairayin bakin teku, saboda haka tsarin shigarwa da ruwa (shoal) yana samar da tushe mai kyau da nutsewa don kasafin kuɗin sediment.

Rashin saukowa a ko'ina cikin bayanin martaba na bakin teku ya dace da ra'ayi mara ma'ana; inda ƙarfin nauyi da na ruwa ke ƙayyade saurin saurin hatsi a cikin rarrabawar saukowa. Tsawon bakin teku yana faruwa a cikin digiri 90 zuwa 80 don haka za a gabatar da shi azaman kusurwar dama tare da layin raƙuman ruwa.

 Abubuwan halitta 
Wannan ɓangaren ya ƙunshi siffofi na doguwar teku wanda ke faruwa a bakin tekun inda doguwar doguwar ruwa ke faruwa ba tare da katsewa ba ta hanyar tsarin mutum.

 Rashin da aka yi 
An kafa spits lokacin da dogon lokaci ya wuce wani batu (misali bakin kogi ko sake shiga) inda shugabanci mai rinjaye da bakin teku ba sa juyawa a cikin wannan hanya. Kazalika da jagorar motsi mai rinjaye, tsinkaye suna shafar ƙarfin halin yanzu, kusurwa raƙuman ruwa da tsawo na raƙuman da ke shigowa.

Spits sune siffofi masu mahimmanci guda biyu, tare da fasalin farko shine yankin a ƙarshen raguwa ko ƙarshen kusa (Hart et al., 2008). Ƙarshen kusa koyaushe yana haɗe da ƙasa (sai dai idan an karya shi) kuma yana iya samar da ɗan ƙaramin "kulle" tsakanin teku da bakin teku ko lagoon  (wanda ake kira peresyp a cikin al'adar Rasha ta geomorphology). Abu na biyu mai mahimmanci shine ƙarshen raguwa ko ƙarshen nesa, wanda aka raba shi daga ƙasa kuma a wasu lokuta, na iya ɗaukar siffar ƙugiya ko ƙuƙwalwa, saboda tasirin hanyoyi daban-daban.

A matsayin misali, New Brighton spit a Canterbury, New Zealand, an halicce shi ne ta hanyar yaduwar laka daga Kogin Waimakariri zuwa arewa. Wannan tsarin kumfa a halin yanzu yana cikin daidaito amma yana fuskantar matakai daban-daban na saukowa da rushewa.

 Shingen 
Tsarin shingen suna haɗe da ƙasa a duka iyakar kusa da na nesa kuma gabaɗaya sun fi faɗi a ƙarshen raguwa. Wadannan tsarin shingen na iya rufe wani bakin teku ko tsarin lagoon, kamar na Lake Ellesmere / Te Waihora wanda ke kewaye da Kaitorete Spit ko hapua wanda ke samuwa a bakin kogi kamar a bakin Kogin Rakaia.

Kaitorete Spit a Canterbury, New Zealand, tsarin shinge ne / shinge (wanda yawanci ya fada ƙarƙashin ma'anar shinge, kamar yadda iyakar ƙasa biyu ke haɗe da ƙasa, amma an kira shi shinge) wanda ya wanzu a ƙarƙashin Banks Peninsula na shekaru 8,000 da suka gabata. Wannan tsarin ya sami sauye-sauye da yawa saboda ruwan kogin Waimakariri (wanda yanzu ke gudana zuwa arewacin Banks Peninsula), rushewa da matakai na yanayin ruwa. Tsarin ya sami ƙarin canje-canje  Shekaru 500 Kafin Yanzu, lokacin da dogon teku ya ɓace daga ƙarshen gabashin tsarin "spit" ya haifar da shingen, wanda aka riƙe shi saboda ci gaba da sufuri mai tsawo. 

 Ruwan ruwa 
Yawancin hanyoyin da ke cikin ruwa a bakin tekun suna tara turɓaya a cikin ambaliyar ruwa da raguwa. Ebb-Deltas na iya zama raguwa a kan gabar da aka fallasa sosai kuma a cikin ƙananan sarari, yayin da ambaliyar ruwa mai yiwuwa za ta karu da girman lokacin da sarari yake a cikin bay ko tsarin lagoon. Ruwan ruwa na iya aiki a matsayin sinks da kuma tushen don adadi mai yawa na kayan, wanda saboda haka yana tasiri a kan sassan da ke kusa da bakin teku.

Tsarin shigarwar ruwa yana da mahimmanci ga tsalle-tsalle mai tsawo: idan ba a tsara shi ba, turɓaya na iya wucewa ta hanyar shiga kuma ya samar da sanduna a ɓangaren da ke ƙasa na bakin teku. Wannan kuma na iya dogara da girman shigarwa, yanayin delta, ƙimar sediment da hanyar wucewa. Bambancin wurin Tashar da adadin na iya rinjayar tasirin doguwar teku a kan hanyar ruwa.

Lagun Arcachon a kudu maso yammacin Faransa misali ne na tsarin shigar da ruwa, wanda ke ba da manyan tushe da nutsewa don tsaunuka masu tsawo. Tasirin tsaunuka masu tsawo a kan wannan tsarin shigarwa yana da tasiri sosai ta hanyar bambancin yawan ƙofofin lagoon da kuma wurin waɗannan ƙofofin. Duk wani canji a cikin waɗannan abubuwan na iya haifar da mummunar lalacewa ko ƙaruwar raguwa na manyan sanduna.

 Tsibirin Sand 
Inda wasu siffofi na halitta suka katse motsi na dogon lokaci, isasshen shimfidar wuri na iya faruwa don samar da tsarin ƙasa na dogon lokaci wanda ya kai ga bakin teku. Tsarin tsari yayi kama da na tsibirin Barrier.Tsibirin shinge.

K'gari ita ce tsibirin yashi mafi girma a duniya, wanda ke kan gabar gabashin Ostiraliya, kuma an kafa ta ne daga katsewar arewacin arewa.

A cikin lokutan da suka fi tsayi, yaduwar yaduwa na iya 'ruwa' cikin ruwa mai zurfi, inda iska da raƙuman ruwa da ke motsawa da tsawo suka fi rauni. Wannan yana ba da damar gina manyan wuraren ajiya na bakin teku, wanda a hankali aka mayar da shi zuwa gabar teku yayin da matakin teku ya fada cikin sake zagayowar glacial na dogon lokaci. 

 Tasirin ɗan adam 
Wannan ɓangaren ya ƙunshi siffofi masu tsawo waɗanda ke faruwa ba bisa ka'ida ba kuma a wasu lokuta (misali groynes, masu rarraba ruwa) an gina su don haɓaka tasirin dakatarwa mai tsawo a kan bakin teku amma a wasu lokuta suna da mummunar tasiri a kan dakatarwa na dogon lokaci (masu tashar jiragen ruwa da tashar jiragen mmiri).

 Groynes 
Groynes sune tsarin kariya na bakin teku, an sanya su a daidai lokaci tare da bakin teku don dakatar da rushewar bakin teku kuma gabaɗaya su haye yankin intertidal. Saboda wannan, yawanci ana amfani da tsarin groyne a kan gabar teku tare da ƙananan net da kuma tsalle-tsalle na shekara-shekara don riƙe abubuwan da suka ɓace a cikin guguwar guguwa da kuma ci gaba da zuwa bakin teku.

Akwai bambance-bambance da yawa ga ƙirar groyne tare da ƙirar uku da suka fi dacewa waɗanda suka haɗa da:

 zig-zag groynes, wanda ke watsar da lalacewar da ke faruwa a cikin raƙuman ruwa ko a cikin raɗaukan ruwa.
 T-head groynes, wanda ke rage tsawo na raƙuman ruwa ta hanyar raƙuman raƙuman.
 'Y' kai, tsarin murfin kifi.

 Yankunan da aka yi 
Har ila yau, wuraren da aka yi amfani da su sune tsarin kariya na bakin teku, waɗanda aka kirkira don samar da wani kariya ga rairayin bakin teku ko bays. Kodayake kirkirar tuddai ya haɗa da karuwa turɓaya a gefen da ke kan tudu da kuma matsakaiciyar lalacewa na ƙarshen tuddai, ana aiwatar da wannan don tsara tsarin da ya dace wanda ke ba da damar kayan su tara a cikin rairayin bakin teku.

Yankunan wucin gadi na iya faruwa saboda tarin halitta ko kuma ta hanyar abinci mai gina jiki.

 Rashin ruwa 
Rashin ruwa mai laushi shine tsarin kariya na bakin teku, wanda aka kirkira don gina kayan yashi don karɓar raguwa a yanayin guguwa. Don karɓar raguwa a cikin yanayin guguwa, ruwa mai raguwa ba shi da alaƙa da bakin teku, wanda ke barin raƙuman ruwa da laka su wuce tsakanin ruwa da bakin teku. Wannan ya samar da yankin rage ƙarfin motsi, wanda ke ƙarfafa zubar da yashi a gefen tsarin.

Ana amfani da masu fashewa a cikin ruwa kamar yadda ake amfani da groynes, don gina girman kayan tsakanin bakin teku da tsarin fashewa don karɓar guguwar guguwa.

 Tashoshin jiragen ruwa da tashoshin jiragen kasa 
Halitta tashar jiragen ruwa da tashar jiragen sama a duk faɗin duniya na iya yin tasiri sosai a kan hanyar halitta ta dogon lokaci. Ba wai kawai tashar jiragen ruwa da tashar jiragen sama suna haifar da barazana ga yaduwar teku a cikin gajeren lokaci ba, suna kuma haifar da barazanar juyin halitta na bakin teku. Babban tasirin, wanda kirkirar tashar jiragen ruwa ko tashar jiragen kasa na iya samun shi a kan doguwar teku, shine canjin alamu na sedimentation, wanda hakan zai iya haifar da karuwa da / ko rushewar rairayin bakin teku ko tsarin bakin teku.

A matsayin misali, kirkirar tashar jiragen ruwa a Timaru, New Zealand a ƙarshen karni na 19 ya haifar da gagarumin canji a cikin tsalle-tsalle mai tsawo tare da iyakar tekun Kudancin Canterbury. Maimakon doguwar doguwar da ke jigilar turɓaya zuwa arewa zuwa gabar teku zuwa tafkin Waimataitai, kirkirar tashar jiragen ruwa ta toshe wannan turɓaya (mai laushi) kuma a maimakon haka ya sa su karu zuwa kudancin tashar jiragen sama a rairayin bakin teku ta Kudu a Timaru.  Haɓakar wannan laka zuwa kudu, saboda haka yana nufin rashin laka da aka ajiye a bakin tekun kusa da tafkin Waimataitai (zuwa arewacin tashar jiragen ruwa), wanda ya haifar da asarar shingen da ke kewaye da tafkin a cikin shekarun 1930 sannan jim kadan bayan haka, asarar tafkin kanta. Kamar yadda yake tare da tafkin Waimataitai, tafkin Washdyke, wanda a halin yanzu yake a arewacin tashar jiragen ruwa ta Timaru, yana fuskantar lalacewa kuma yana iya rushewa, yana haifar da asarar wani yanayin tafkin.

 Dubi kuma 

 Manazarta 

Rukuni:Shafuka masu fassarorin da ba'a duba ba