Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory


Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory
Hywel Meilyr Griffiths

Mae’r papur hwn yn cyflwyno adolygiad o’r ymchwil geomorffeg afonol a wnaed ar afonydd Cymru. Yn ogystal â thrafod tueddiadau a welir yn yr astudiaethau hyn, yn gyntaf drwy ganolbwyntio ar waith daearegwyr ar ddiwedd y bedwaredd ganrif ar bymtheg, a thrwy symud ymlaen drwy ddatblygiad geomorffeg yn faes ymchwil i’r cyfnod rhyngddisgyblaethol presennol, trafodir y meysydd sydd wedi cael sylw arbennig ar afonydd Cymru. Mae’r rhain yn cynnwys esblygiad mega-geomorffeg Cymru, astudiaethau proses arloesol, esblygiad systemau afonol llifwaddodol i newidiadau hinsoddol tymor byr a thymor hir, ac ymateb afonydd Cymru i weithgarwch anthropogenig. Mae’r amrywiaeth hon o astudiaethau yn ganlyniad natur systemau afonol Cymru. Yn gyntaf, maent yn dangos hanes esblygol, gan gynnwys cyfnodau rhewlifol ac adnewyddiad. Yn ail, mae prosesau cyfoes wedi creu amrywiaeth eang o fathau o sianeli, gan gynnwys sianeli creigwely, afonydd gwely graean, sianeli troellog, plethog, sefydlog ac ansefydlog. Yn drydydd, mae diddordeb academaidd a phryderon pragmatig ynghylch rheoli afonydd wedi arwain at gorff mawr o waith sydd, mewn rhai achosion, yn golygu bod nifer o rannau o afonydd Cymru yn cael eu hystyried yn archdeipiau rhyngwladol. Trafodir bylchau yn ein gwybodaeth hefyd. Mae’r rhain yn cynnwys yr angen i gynyddu ein dealltwriaeth o brosesau cyfoes a pharhau â’r gwaith a wnaed ar ymateb ac esblygiad llifwaddodol drwy ddefnyddio’r technegau diweddaraf i gadw cronoleg datblygiad systemau afonol. Mae angen ehangu cwmpas gofodol ein hastudiaethau i ardaloedd nad ydynt wedi cael cymaint o sylw yn y gorffennol, megis sianeli llifwaddodol creigwely a chreigwely cymysg y gogledd-orllewin a chymoedd de Cymru.


Cyfeiriad:

 
  	Hywel Meilyr Griffiths, 'Geomorffeg afonol Cymru: Heddiw, ddoe ac yfory', Gwerddon, 3, Mai 2008, 36-70.
   

Allweddeiriau

 
    Geomorffeg, afonydd, Cymru.
    

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