{"id":11625,"date":"2026-09-21T11:10:20","date_gmt":"2026-09-21T10:10:20","guid":{"rendered":"https:\/\/afonyddcymru.cambrianweb.dev\/?p=11625"},"modified":"2026-10-17T22:45:02","modified_gmt":"2026-10-17T21:45:02","slug":"isaf-ymweld-ar-cofnod-2-3","status":"publish","type":"post","link":"https:\/\/afonyddcymru.cambrianweb.dev\/cy\/isaf-ymweld-ar-cofnod-2-3\/","title":{"rendered":"Lefelau Isaf Erioed Wedi\u2019u Cofnodi mewn Afonau ar draws Cymru"},"content":{"rendered":"

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Mae llawer o afonydd Cymreig yn teimlo manteision d?r ychwanegol o gronfeydd d?r, ac mae gan eraill orsaf fesur sy'n cofnodi'r lefelau isaf erioed.<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>

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Dydd Llun 17 Awst 2026<\/h2><\/div>\n\t\t\t<\/div>
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Mae dadansoddi data lefel afonydd Cymru gan Afonydd Cymru yn dangos llun pryderus o uchderau d?r ar \u00f4l y ton berfeddol ddiweddar, gyda llawer o orsaf fesur Adnoddau Naturiol Cymru yn cofnodi'r lefelau lleiaf erioed erbyn hyn.<\/p>\n

Ar hyn o bryd, mae 28 o orsaf fesur ledled Cymru yn cofnodi'r lefelau lleiaf erioed (er y sefydlwyd yr orsaf), gyda 46 arall o fewn 3cm o'r marc hwn.<\/span><\/p>\n

Mae llawer o'r gorsafoedd sy'n cofnodi'r lefelau lleiaf erioed ar is-afonydd. Mae hyn yn newydd da ddim i rywogaethau pysgod sydd eisoes mewn perygl fel samwn yr Iwerydd ac yn enwedig sewin, sydd eu hieuenctid yn byw yn bennaf yn y ffrydiau bychain.\u00a0<\/p>\n

Mae'r lefelau is yn golygu tymheredd uwch, lefelau ocsigen is, mwy o berygl i'r pysgod bach hyn gael eu hela, a'r siawns uwch y bydd ffrydiau'n sychu i'r eithaf.<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>

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Darllenni gorsaf mesur Cyfoeth Naturiol Cymru ar afonydd mawr Cymru ar 17eg Awst 2026. Mae\u2019r rhai mewn coch yn afonydd i lawr yr afon o orsaf fesur gyda lefel isaf a gofnodwyd ar gyfer yr orsaf honno neu\u2019n is. Mae\u2019r rhai mewn oren yn o fewn 3cm o\u2019r lefel isaf a gofnodwyd. Mae\u2019r rhai a ddangosir mewn glas yn fwy na 3cm uwch na\u2019u lefel isaf a gofnodwyd (er y gallent dal fod yn is na lifoedd \u201cnormal\u201d).<\/strong><\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>

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Mae d?r ychwanegol o'r cronfeydd d?r yn helpu rhai afonydd<\/h3><\/div>\n\t\t\t<\/div>
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Mae prif gangen afonydd Cymreig sydd wedi\u2019u cynnal gan ddyfrgelloedd yn dangos arwyddion o lifau gwell, sydd yn dystiolaeth i ofynion Adnoddau Naturiol Cymru i fwy o dd?r gael ei ryddhau gan Dd?r Cymru a Hafren Dyfrdwy.<\/p>\n

Er enghraifft, ymddengys bod y Dyfrdwy (afon 7 ar y map) o fewn neu ychydig o dan y lefelau arferol ar \u00f4l rhyddhau ychwanegol o\u2019r pedair ddyfrgell sy\u2019n ffurfio Cynllun Rheoleiddio Dyfrdwy.\u00a0<\/p>\n

Mae prif gangen y Tywi (16) hefyd yn dal i sefyll yn eithaf da yn y sychder, ar \u00f4l rhyddhau gan Llyn Brianne a ofynnwyd gan Adnoddau Naturiol Cymru, gan hynny hefyd mae uchaf Afon Hafren (10) sydd wedi\u2019i chynnal gan Ddyfrgell Clywedog a Llyn Vyrnwy.\u00a0<\/p>\n

Fodd bynnag, mae dau o ganghennau Dyfrdwy nad ydynt yn derbyn d?r o ddyfrgelloedd (y Ceiriog a\u2019r Clywedog) a un o ganghennau\u2019r Tywi (Twrch) ar y lefelau isaf a gofnodwyd erioed, gan ddangos beth allai sefyllfa\u2019r afonydd sydd wedi\u2019u dynodi fel SAC fod pe na baent wedi derbyn y d?r ychwanegol.<\/p><\/div>\n\t\t\t<\/div>

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Canol a De Ddwyrain Cymru<\/h3><\/div>\n\t\t\t<\/div>
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Ar yr un pryd, dydy'r Wysg (21) ddim yn gwneud cystal. Mae un o'i phrif fesurwyr brwyn (yn Nghricihoel) ar y lefel isaf a gofnodwyd, fel y mae dau ganghennau pwysig: y Senni a'r Ysgir.<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>

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Ac mae\u2019r sefyllfa ar y Wye gyfagos (13), sy\u2019n derbyn d?r ychwanegol o Gamls Elan, yn fwy pryderus fyth. Mae dros 50% o fesurwyr Adnoddau Naturiol Cymru yn eu lefel isaf a gofnodwyd erioed, gan gynnwys y rheini ar ganghennau uchel pwysig y afon, yr Irfon.<\/p><\/div>\n\t\t\t<\/div>

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Ynys M\u00f4n a'r Gogledd<\/h3><\/div>\n\t\t\t<\/div>
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Rhan arall o Gymru sydd yn peri pryder penodol yw Ynys M\u00f4n, lle mae afonydd Rhyd y Glyn a Frogwy ar neu dan y lefelau isaf a gofnodwyd erioed, fel rhai sbriws ar afonydd arall pwysig Gogledd Cymru, fel y Gwyrfai (3), Dyfi (9) a Dysynni.<\/p>\n

Ar yr un pryd, mae\u2019r Seiont (2), un o\u2019r rhai ambell afon yng Nghymru lle mae poblogaethau eog wedi bod yn gyson, yn agos\u00e1u at ei lefel isaf erioed a gofnodwyd.<\/p><\/div>\n\t\t\t<\/div>

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Roedd Hafren Dyfrdwy yn adrodd bod Llyn Clywedog, sydd yn cynnal llifiau yn y Hafren, wedi gostwng i 62.2% o'r capasiti ar 3ydd Awst.<\/p><\/div>\n\t\t\t<\/div>

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De a Gorllewin<\/h3><\/div>\n\t\t\t<\/div>
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Mae dalgylch arall sydd wedi cael ei effeithio yn y T\u00e2f (23) yn Ne Ddwyrain Cymru. Mae'r prif gangen yn isel ond mae prif ganghennau fel y Cynon a'r Rhondda i gyd yn cofnodi'r lefelau isaf erioed.<\/p>\n

Mae'n edrych fel bod Gorllewin Cymru yn yr ardal lle mae'r lefelau'n dal y gorau, hyd yn oed cyn ychydig iawn o law a syrthiodd dros y penwythnos.\u00a0<\/p>\n

Fodd bynnag, hyd yn oed yn yr ardal hon, mae adrannau o'r Cleddau Gorllewinol (17), T\u00e2f (18) a Ystwyth (12) ar y lefel isaf erioed neu'n agos ati.<\/p><\/div>\n\t\t\t<\/div>

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Gobeithio am rywfaint o ryddhad ar y gorwel?<\/h3><\/div>\n\t\t\t<\/div>
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Mae tywydd dros y dau wythnos nesaf yn rhagweladwy i fod yn fwy anhaggar gyda rhai glawydd yn dod o\u2019r gorllewin.<\/p>\n

Er lles nifer o afonydd ledled Cymru a\u2019u poblogaethau pysgod, ni all y torri hwn yn sychder ddod yn fuan digon.<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>

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Postio:<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>

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\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\t<\/div><\/p>\n","protected":false},"excerpt":{"rendered":"

Mae llawer o afonydd Cymreig yn elwa o dd?r ychwanegol o ffrydiau, ac mae gan eraill orsafoedd mesur sy’n cofnodi’r lefelau isaf a gofnodwyd…..<\/p>\n","protected":false},"author":3,"featured_media":11758,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[34,1],"tags":[],"class_list":["post-11625","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-projects","category-uncategorized"],"yoast_head":"\nLefelau Isaf Erioed Wedi\u2019u Cofnodi mewn Afonau ar draws Cymru - Afonydd Cymru<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/afonyddcymru.cambrianweb.dev\/river-data-hub-post\/\" \/>\n<meta property=\"og:locale\" content=\"cy_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Lefelau Isaf Erioed Wedi\u2019u Cofnodi mewn Afonau ar draws Cymru - 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