Ruwa mai nauyi

Ruwa mai laushi kalma ce ta ilimin ƙasa da ke nufin abu mai ƙarfi da rafi ke ɗauka (Strahler da Strahler, 2006). Rugujewar ƙasa da damuwa game da shimfiɗa gado suna ci gaba da cire kayan ma'adinai daga gado da bankunan tashar rafi, suna ƙara wannan kayan ga kwararar ruwa ta yau da kullun. Adadin nauyin da rafi zai iya ɗauka, ko ƙarfin rafi, ana auna shi a cikin tan na mita a kowace rana, yana wucewa da wurin da aka ba shi. Rashin ƙarfin rafi ya dogara da saurin rafi, yawan ruwa, da gradation (saboda rafi da ke faruwa a kan gangaren da suka fi tsayi suna da babban gudana da sauri) (Strahler da Strahler, 2006).

## Nau'o'in rushewar rafi
Akwai manyan tushe guda biyu na rushewar rafi: aikin ruwa da Abrasion. Dukkanin kayan da aka kara zuwa kwararar rafi ta al'ada ta hanyar waɗannan matakai suna ƙara nauyin rafi gaba ɗaya (Strahler da Strahler, 2006).

### Ayyukan ruwa
Ayyukan hydraulic suna bayyana rushewar da aka haifar ta hanyar jan ruwa a kan kogin da banki. Wannan jan hankali, haɗe da tasirin ƙananan jam'iyyun, yana sauƙaƙewa da lalata ƙananan al'amuran ruwa, kamar dutse, yashi, laka da yumɓu (Mangelsdorf, 1990). Ɗaya daga cikin misalai masu ƙarfi na aikin ruwa shine kogon banki, wanda yawanci ke faruwa lokacin da rafi ya kwantar da turɓaya kuma ya yanke banki. Sakamakon haka, manyan tarin laka suna raguwa kuma suna rushewa cikin rafin, suna ƙarawa sosai ga nauyin rafin (Strahler da Strahler, 2006). Matsayin aikin hydraulic yana ƙaruwa tare da saurin rafi da nauyin rafi na yanzu.

### Abun da aka yi
Abrasion yana faruwa ne lokacin da manyan barbashi na dutse suka mirgine kuma suka buge ganuwar dutse, suna fashewa da fashewa barbashi da ɓangarorin dutse (Strahler da Strahler). Yayin da waɗannan duwatsu da duwatsu ke juyawa a fadin rafin, suna ci gaba da murkushewa da niƙa dutsen, suna samar da nau'ikan nau'ikan dutse masu lalacewa (Ritter, 2006). Har ila yau, tsananin irin wannan rushewa ya dogara da saurin rafi da nauyin rafi (watau kasancewar manyan barbashi na dutse).

## Nau'o'in kaya na rafi
Abubuwan ma'adanai na siffofi daban-daban da girman ƙwayoyin suna lalacewa kuma suna ba da gudummawa ga nauyin rafi gaba ɗaya. Bambance-bambance a cikin girman waɗannan kayan ya ƙayyade yadda za a kai su cikin rafi. Ana karkatar da nauyin rafi zuwa nau'o'i uku: nauyin da aka narke, nauyin da aka dakatar, da nauyin gado (Ritter, 2006).

### Rashin nauyi
Abubuwan da aka narke ba su ganuwa, kuma ana jigilar su a cikin nau'ikan ions na sinadarai. Dukkanin koguna suna ɗauke da wani nau'in kayan da aka narke. Wannan nau'in kaya na iya haifar da Canjin ma'adinai daga rushewar sinadarai, ko ma ya zama sakamakon ruwan kasa a cikin rafin. Kayan da suka hada da nauyin da aka narke suna da mafi ƙanƙanta girman ƙwayoyin nau'ikan kaya guda uku (Strahler da Strahler, 2006).

### An dakatar da kaya
Kayayyakin da aka rataye sun hada da ƙananan barbashi da aka dakatar kuma aka kai su ta hanyar rafin. Wadannan kayan sun yi yawa don a narke su, amma sun yi ƙanƙanta don kwance a kan gadon rafin (Mangelsdorf, 1990). Gudun rafi yana kiyaye waɗannan kayan da aka dakatar, kamar yumɓu da laka, daga zama a kan gado na rafi. Rashin ɗaukar kaya shine sakamakon kayan da aka lalata ta hanyar aikin ruwa a saman rafin da ke kan iyakar tashar da kuma rushewar tashar kanta. Rashin nauyin da aka dakatar da shi shine mafi yawan nauyin rafi (Strahler da Strahler, 2006).

Abun gado yana juyawa a hankali tare da bene na rafin. Wadannan sun hada da mafi girma da kuma mafi nauyi a cikin rafin, daga yashi da karafa zuwa dutse da duwatsu. Akwai manyan hanyoyi guda biyu don jigilar kaya a gado: traction da gishiri. Traction ya bayyana "scooting da rolling" na barbashi tare da gado (Ritter, 2006). A cikin jigilar kaya na rafi, gishiri motsi ne mai kama da bounce, wanda ke faruwa lokacin da aka dakatar da manyan barbashi a cikin rafi na ɗan gajeren nesa bayan haka suka faɗi zuwa gado, suna fitar da barbashi daga gidan. Abubuwan da aka cire suna motsawa zuwa ƙasa a ɗan gajeren nesa inda suka faɗi zuwa gado, sake sassauta barbashi a kan tasiri (Ritter, 2006).

## Ambaliyar ruwa da nauyin rafi
Ambaliyar ruwa ta haifar da yanayin da rafi ke gudana da saurin gudu ba su da yawa saboda ƙara ruwa zuwa rafi. Wadannan halaye masu girma suna kara yiwuwar lalacewar rafi da nauyin rafi mai nauyi (Knighton, 1998). Kogunan ambaliyar ruwa galibi suna da alhakin jigilar kaya mai nauyi da kuma ajiyewa a cikin ruwa. Rashin ƙarfin rafi ya karu sosai a lokacin ambaliyar ruwa (Knighton, 1998). A lokacin ambaliyar ruwa, ana iya ganin karuwar nauyin da aka dakatar, yana ba da rafin launi mai laka.

## Manazarta

* Knighton, David. (1998). Hanyoyi da Hanyoyi na Ruwa: Sabon hangen nesa, London: Arnold.
* Mangelsdorf, J. da sauransu (1990). River Morphology: Jagora ga Masana kimiyya da Injiniyoyi, Berlin: Springer-Verlag .
* [Hasiya] *Muhalli na Jiki: Gabatarwa ga Yanayin Jiki: Aikin Geologic na Koguna* . An ziyarta: Maris 2, 2008. *https://web.archive.org/web/20080516233555/http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/icecap.html* 
* Strahler, A. da A. Strahler. (2006). *Gabatar da Yanayin Jiki*, Boston: Wiley & Sons.