Imifula inezimo ezihlukene endleleni yayo. Enye yazo yi- i-mender. Kuyijika lomfula elakheka ngesikhathi semifula ngenxa yenhlanhla yomfula owashayelayo. Amajika emifula aphakeme kakhulu akhonjwa njengama-menders futhi anesikhathi esilinganiselwe.
Kulesi sihloko sizokutshela konke okudingeka ukwazi mayelana ne-mender, izici zayo kanye nokwakheka kwayo.
Izici eziyinhloko
I-Meanders isetshenziselwa ukuveza izinhlobo ezithile zemifula ngokusekelwe ekwakhiweni kwayo. Kunezinhlobo ezintathu zama-tributaries: aluka, aqondile, futhi agobile noma inyoka. Emifuleni egeleza esigodini. ama-menders ngokuvamile alula ukwakha lapho umthambeka umncane.
Intlenga ivamise ukufakwa eqhumeni ngendlela emazombezombe bese isuka lapho iye ogwini. Ezindaweni ezingemuva ukuguguleka kuyabusa, futhi kusobala ukuthi udonga luhlehla kanjani ngenxa yamandla amaphakathi. Lapho ukuqhubekela phambili konqenqema endaweni eyi-convex kuhlanganiswe nokuhlehla kwendawo eyi-concave, inkambo yomfula iqala ukufuduka bese kuvela ama-mender.
Kulula ukubona noma ukuhlukanisa kwezinye izinhlobo zemifula, ngoba isici sayo esiyinhloko ijika elijikayo elisobala kakhulu elakhayo ogwini lomfula. Kwesinye isikhathi ziqanjwa ngesifunda semvelaphi yazo. Abizwa ngokuthi ama-galacho emfuleni i-Ebro yase-Aragon, futhi abizwa ngokuthi yixhaphozi eligudla uMfula iMississippi e-United States.
Lapho ukugeleza kwe-mendering kwenza ijika elikhulu kakhulu, kungabangela ukuguquka komfula. Ahlala enyakaza ezindaweni ezithile njengasemathafeni, ngakho angakheka okuthiwa yichibi elimise okwe-mender endaweni ethile. Indlela ejikajikayo yomfula ngamunye ihlukile ngoba incike ekugelezeni kwawo, isivinini samanzi nezinto eziwakhayo.
Indlela i-mender yakheka ngayo
Amanzi emfuleni ahlala egeleza ohlangothini olulodwa, okunqunywa ukuthambekela kwendawo lapho ehamba khona, nakuba ngezinye izikhathi ingaphezulu libonakala liyisicaba.
Ukuze uyihlole, ungenza isilingo esilula. Faka amanzi epayipini, kungabonakala ukuthi isivinini sokugcwalisa amanzi siyanda noma siyancipha; isivinini sincike ekuthambekeni kwepayipi.
Kungokufanayo nangombhede womfula. Amanzi ageleza emseleni; lapho indawo ikhuphuka, ijubane lokugeleza kwamanzi likhulu futhi ngenxa yalokho kuba namandla amakhulu kuwo. Yiwo la mandla aguguleka umhlaba, okwenza umzila womfula ugobe.
Njengoba umfula uhamba phezu kwendawo enezimbotshana, ekwazi ukungena emanzini, emaphethelweni omzila wemvelo umfula oqhubeka nokugeleza kuwo uyaguguleka. Njengoba iguga ithola ukwakheka kwe-concave okuyisici, okwenza ijika.
Ngokusho kwezazi zokwakheka komhlaba, inqubo yokuzungeza kwenzeka ngezinyathelo ezintathu: ukugqwala, ukuguguleka nokuguga. Okokuqala, amandla asheshayo amanzi noma ukucindezela kwamanzi kugqwala osebeni lomfula futhi kuthathe umhlabathi, amatshe namatshe.
Ngakho-ke le nto enyakaziswa amandla amanzi isiza ukuguguleka umbhede womfula. Ekugcineni, izinhlayiya zezinto ezihlukene nezishayisanayo ziyashayisana; lokhu kubangela ukuguga, okwandisa amandla abhubhisa izisekelo zombhede womfula.
Ngendlela efanayo ukuthi ukuguguleka kwangaphandle kwenza ijika, inzika nayo inqwabelana kwelinye ibhange, yenze i-convex noma uhlangothi lwangaphakathi lwejika. Imigudu ye-Fluvial ngokuvamile yakheka phakathi nendawo emifuleni ephansi; azivamile ukwenzeka emthonjeni. Lokhu kungenxa yokuthi kuyingxenye engezansi noma emaphakathi yomfula lapho umsinga uletha khona ukucindezela okukhulu namandla. I-Meanders ingashintsha indawo futhi ishintshe nendlela yomfula.
Izinhlobo ze-Meander
Kukhona ukusonteka okusobala kakhulu nokunye ukusonteka okuncane; lokhu kungenxa yamandla e-centrifugal amanzi njengoba edlula ejikeni. Ubukhulu bomfula buphinde bube nomthelela: lapho umfula ukhula, kuba sobala kakhulu ukujika nokujika.
Amandla amanzi nawo angancishiswa. Kulesi simo, ijika ligcwalisa amadiphozithi kuze kube yilapho okwamanje iyeka ukugeleza emkhakheni futhi i-zigzag iyanyamalala. Esikhundleni salokho "ichibi elimise okwe-meander," leli gama elivamile elishintshiwe. Kunezinhlobo eziningana zama-menders:
I-mender eshumekiwe
Kuwuhlobo lomonakalo ojulile edwaleni lomfula. Lapho ukukhululeka kokujikeleza kwamanje kolwandle kukhula ngenxa yokunyakaza kwe-tectonic, umzila wamanzi ozungezayo uqala kabusha inqubo yawo yokuguguleka eya phansi. Le nqubo ibizwa ngokuthi i-rejuvenation.
Izigodi ezimazombezombe zifana nezigodi ezakha uMfula iColorado eGrand Canyon yase-United States. Lapho izinga lolwandle lehla, ithonsi lamanzi lingaphinda lenze i-mender egxilile. Kunezinhlobo ezimbili zama-menders ashumekiwe:
I-Meander inwetshiwe
Kuyinto ukunyakaza lateral, okuyinto elinganiselwe kakhulu ngenxa ukwehla kwezinga lesisekelo kanye nokwehla okulandelanayo kwesivinini sokugeleza kwamanzi. Inomthambeka ongama-sedimentary engxenyeni ephuma ebhange kanye nokunye ukuguguleka lapho iphumela khona.
I-Valley meander
Kuyi-meander efakwe ngendlela efanele ngoba ayibangeli ukunyakaza kwe-lateral okubalulekile. Sakhiwe ukugeleza kwamanzi antantayo endaweni ecishe ibe yithafa enezingqimba ezimbalwa. Njengoba yehla izinga eliyisisekelo lamanzi omfula, imisinga enyakazayo idala ukusikeka okujulile emhlabathini.
I-Rambling meander
Kuyi-mender yamahhala, evame kakhulu emathafeni e-alluvial anemithambeka embalwa noma izinsalela ezingahlanganisiwe. Lokhu kuvumela ijika ukuthi liguquke ngokuhamba kwesikhathi; kucatshangelwa olunye uhlobo lwezigzag.
Ilahliwe
Yakha lapho i-mender egxilile isikwa ukuze yakhe ichibi elimise okwesicathulo sehhashi. Izwe lonke laziwa ngaleli gama. Isibonelo iLake Powell eningizimu-ntshonalanga ye-United States, eyaziwa nangokuthi "i-El Rincón." La machibi amise okwezicathulo zehhashi aqala lapho ama-meaders ekhula futhi eqala ukuwela nokuwelana. Usebe lomfula alunawo amanzi asebenzayo; Ngokuhamba kwesikhathi, le mingenela yomfula engasasebenzi iyoma futhi igcwale inzika.
Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana nokuthi iyini i-meander nezici zayo.