Ukuqonda Igama elithi Meander kwiJografi
Ekufundweni kwejografi, ikakhulukazi i-geomorphology kanye ne-hydrology, imifula iqondwa njengokungaphezu nje kwemifudlana yamanzi egeleza esuka phezulu iye phansi. Ziyizinhlelo eziguquguqukayo ezishintsha njalo isimo ngokwezimo zemvelo ezizungezile. Esinye sezici ezivelele kakhulu zokugeleza komfula ukugoba. Leli gama libhekisela ekugobeni emfuleni okwakha amajika aphindaphindwayo, ngezinye izikhathi afana nohlamvu "S" uma ubhekwa ngenhla. Ukuba khona kwama-meanders kuyisibonakaliso esibalulekile sobuntu be-watershed (DAS), uhlobo lomhlabathi, umthambeka womhlaba, kanye nezinqubo eziqhubekayo zokuguguleka kanye nokuchitheka kwenhlabathi.
Incazelo kaMeander
Kalula nje, ukugoba kuwukugoba noma ukugoba kokugeleza komfula okwakheka ngokwemvelo ngenxa yokuguguleka komhlabathi kanye nokuchitheka kwawo. Ama-meander ngokuvamile akhula emifuleni egeleza ezindaweni eziyisicaba noma ezithambekele kancane, ikakhulukazi phakathi nendawo kuya ezindaweni eziphansi zomfula. Kulezi zindawo, amandla omfula awasaqondiswe kakhulu ekugugulekeni okuqondile (phansi), kodwa kunalokho ekugugulekeni okusemaceleni (eceleni), ngakho umfula uvame "ukugoba" endleleni elula.
Igama elithi meander ngokwalo livela eMfuleni iMaeander (manje owaziwa ngokuthi uMfula iBüyük Menderes) eTurkey, owaziwa ngokugoba kwawo okuyinkimbinkimbi. Kukuleli mfula lapho igama elithi meander lisetshenziswa khona kakhulu kwisayensi yomhlaba ukuchaza iphethini yokugeleza komfula ogobayo.
Izici zeMifula iMeander
Imifula enesimo sokujika ingabonakala ngezici eziningana eziyinhloko:
1. Indlela yomfula igoba ngamajika acacile futhi aphindaphindwayo.
2. Kukhona uhlangothi lwangaphandle olugugile lwejika (ngokuvamile olwenza usebe lomfula oluqinile).
3. Kukhona uhlangothi lwangaphakathi lwe-gobe oluhlangabezana nokubola kwenhlabathi (okwakha izigxobo zesihlabathi noma ama-alluvial deposits).
4. Ukugeleza kuhamba kancane futhi kubanzi kunemifula esezindaweni ezinezintaba ezivame ukugoba futhi zigeleze ngokushesha.
5. Kungenzeka ukuthi kwakheke ichibi le-oxbow uma kugoba.
Lezi zici zibonisa ukuthi ukugoba kungumphumela wokulinganisela okuguquguqukayo phakathi kwamandla okugeleza kanye nezinto ezithuthwa umfula.
Inqubo Yokwakheka Kwe-Meander
Ukwakheka kwama-meander akwenzeki ngobusuku obubodwa. Uchungechunge lwezinqubo zemvelo eziphindaphindayo lubumba kancane kancane amajika emifuleni. Ngokuvamile, ukwakheka kwama-meander kuhlobene nezinqubo ezimbili eziyinhloko: ukuguguleka komhlabathi kanye nokuchitheka kwenhlabathi.
1. Ukuqala kokungazinzi kokugeleza kwamanzi
Umfula oqala ugeleza uqonde ungabhekana nokuphazamiseka okuncane, njengokwehluka kobulukhuni bamadwala, ukuvinjelwa kwezitshalo, noma ukwehluka kokugeleza kwamanzi. Lokhu kuphazamiseka okuncane kubangela ukugeleza ukuthi kugobe kancane.
2. Ukuguguleka kwenhlabathi ngaphandle kwegoba
Uma amanzi egoba, ijubane lokugeleza alilingani. Ngaphandle kokugoba, ukugeleza kuvame ukuba ngokushesha nangokuqinile, kukhukhule ugu lomfula. Le nqubo ibizwa ngokuthi ukuguguleka kwe-lateral futhi iholela ogwini oluqinile (oluvame ukubizwa ngokuthi ugu lokusika).
3. Ukuthungwa kwenhlabathi ngaphakathi kwegoba
Okwamanje, ngaphakathi kwejika, ukugeleza kuhamba kancane, okuvumela izinto ezinjengodaka nesihlabathi ukuthi zihlale. Lolu daka lwakha ithafa elincane noma indawo engenalutho ebizwa ngokuthi i-point bar.
4. Ukufuduka kwe-Meander
Njengoba ukuguguleka komhlabathi kanye nokuchitheka kwawo kuqhubeka, ukugoba komfula kuzohamba kancane kancane. Amajika azoqina futhi umsele womfula uzokhula kancane kancane.
5. Ukwakheka kwezicucu ze-meander
Njengoba ukugoba kuba bukhali, ibanga eliphakathi kwamagoba amabili aseduze lingaba lincane kakhulu (elibizwa ngokuthi intamo egobile). Ngesikhathi sezikhukhula ezinkulu, amanzi angadlula intamo, adale indlela emfushane neqondile yomfula.
6. Ukwakheka kwamachibi e-oxbow
Amajika amadala anqunyiwe emfudlaneni omkhulu angaphenduka amachibi amise okwesicathulo sehhashi (amachibi e-oxbow) noma ekugcineni abe amaxhaphozi uma embozwe yinhlabathi.
Lolu chungechunge lwezinqubo luchaza ukuthi ama-meanders ayizindlela zomfula ezihlala zithuthuka, zishintsha, ngisho “zinyamalale” futhi zakha izinhlobo ezintsha zomhlaba.
Izici Ezithonya Ukwakheka Kwe-Meander
Akuzona zonke izifula eziphenduka imifula egobile. Izici eziningana zemvelo zenza ukwakheka kwemifula kube lula kakhulu:
1. Umthambeka wezwe (umthambeka)
Ama-Meander avame kakhulu ezindaweni ezine-gradient ephansi noma izindawo ezisicaba. Ezindaweni eziqongile, imifula ivame ukuba iqonde futhi igxile kakhulu ekugugulekeni kwenhlabathi okuya phansi.
2. Uhlobo kanye nesakhiwo senhlabathi/idwala
Inhlabathi ethambile kakhulu enama-alluvial iguguleka kalula futhi yakha ama-wind. Idwala eliqinile kunzima kakhulu ukulibumba, okuvumela amaphethini emifula alawulwa kakhulu.
3. Izinga lokukhishwa kanye nokugeleza kwamanzi
Ukugeleza kwamanzi okuzinzile nokukhulu ngokwanele kusekela ukwakheka kwama-meanders, ngoba umfula unamandla okugugula idwala ngakolunye uhlangothi bese ubeka inhlabathi kolunye.
4. Umthwalo wendle
Imifula ethwala inqwaba yenhlabathi ivame ukufaka amatshe ngaphakathi kwamajika, okusheshisa ukuthuthukiswa kwamatshe ajikayo.
5. Izitshalo nemisebenzi yabantu
Izitshalo zingaqinisa usebe lwemifula, ngaleyo ndlela zinciphise ukuguguleka komhlabathi. Ngakolunye uhlangothi, imisebenzi yabantu efana nokuhlanzwa komhlaba, ukumbiwa kwesihlabathi, noma ukwakhiwa kodonga kungashintsha ukuguquguquka kwemifula.
Umthelela Wezinto Ezimbi Emvelweni Nasekuphileni Komuntu
Ukuba khona kwama-meanders akuyona nje into ethakazelisayo yemvelo, kodwa futhi kunomthelela wangempela emvelweni nasemisebenzini yabantu.
1. Ukwakheka kwezindawo ezivundile zezikhukhula
Ama-meander avame ukuhluma emathafeni anezikhukhula. Udaka kanye nezihlabathi ezincane ezitholakala ezikhukhuleni ngezikhathi ezithile kwenza inhlabathi ivunde futhi ifanelekele ezolimo.
2. Ingozi yokuguguleka kwamadwala nokulahlekelwa umhlaba
Uhlangothi lwangaphandle lwe-maender oluqhubeka nokuguguleka lungaguguleka umhlaba wezolimo, izindawo zokuhlala, noma ingqalasizinda osebeni lomfula.
3. Kungenzeka ukuthi kube nezikhukhula
Imifula egobhozayo ivame ukutholakala ezindaweni eziyisicaba ezivame ukuba nezikhukhula. Lapho ukugeleza kwanda, amanzi agcwala emathafeni azungezile.
4. Izinguquko emifuleni
Ukufuduka kwabantu ngendlela exakile kungashintsha imingcele yomhlaba, kuphazamise ukuhlela indawo, futhi kuthinte ngisho nemingcele yokuphatha uma imifula isetshenziswa njengezilinganiso zesifunda.
5. Indawo yokuhlala yemvelo
Amachibi ase-Oxbow, amaxhaphozi, nezindawo eziseduze nemifula ezizungeze imifula zivame ukunikeza indawo yokuhlala ebalulekile yezinhlanzi, izinyoni, kanye nezinhlobo ezahlukene zezinto eziphilayo zasemanzini.
Izibonelo Zezinhlobo Ze-Meander Emvelweni
Ama-Meander angatholakala emifuleni eminingi emikhulu emhlabeni jikelele, njengoMfula iMississippi (e-United States), owaziwa ngokugoba kwawo okubanzi, kanye nemifula eminingana ezindaweni eziphansi zase-Asia naseYurophu. E-Indonesia, amaphethini ajikelezayo avame ukubonakala emifuleni ezindaweni eziphansi, ikakhulukazi eKalimantan, empumalanga yeSumatra, nasePapua, enezindawo ezibanzi nezisicaba.
Isiphetho
Ku-geography, i-meander iwukugoba komfula okwakhiwa ukusebenzisana kokuguguleka komhlaba ngaphandle kwe-gond kanye nokuchitheka komhlaba ngaphakathi. Le ndlela ivame ukwenzeka emifuleni egeleza emithambekeni ethambile, ikakhulukazi phakathi nendawo kuya ezindaweni eziphansi. Ama-meander abonisa isimo esiguquguqukayo semifula: iziteshi zawo zingaguquguquka, zinqume ukugoba, futhi zakhe izimo ezintsha zomhlaba njengamachibi e-horseshoe. Ukuqonda ama-meander kubalulekile hhayi kuphela kwisayensi yomhlaba, kodwa futhi nasekuhleleni kwesifunda, ekunciphiseni izikhukhula kanye nokuguguleka komhlaba, kanye nokuphathwa kwemvelo okusimeme kwemifula.
Uma uthanda, ngingangeza nemifanekiso elula, isakhiwo sezihloko zemisebenzi yesikole (isingeniso–okuqukethwe–isiphetho), noma uhlu olufushane lwezincwadi.
