Asesiad Perygl Llifogydd Cymru
Mae Asesiad Perygl Llifogydd Cymru yn darparu asesiad cenedlaethol o berygl llifogydd o afonydd, y môr a dŵr wyneb a chyrsiau dŵr bychain (gan ddisodli set ddata Perygl Llifogydd o Afonydd a'r Môr).
Mae'r asesiad yn ystyried amddiffynfeydd rhag llifogydd ac yn cyfuno gwaith modelu newydd ar raddfa genedlaethol â modelau manwl ar raddfa leol i greu tri band o ddosbarthiad risg o dan y labeli 'Uchel', 'Canolig' ac 'Isel'.
Ar gyfer Afonydd a Dŵr Wyneb a Chyrsiau Dŵr Bach:
Mae risg ‘Uchel’ yn golygu bod siawns o lifogydd o fwy nag 1 mewn 30 (3.3%) bob blwyddyn yn yr ardal hon.
Mae risg ‘Ganolig’ yn golygu bod siawns o lifogydd o rhwng 1 mewn 100 (1%) ac 1 mewn 30 (3.3%) bob blwyddyn mewn ardal.
Mae risg ‘Isel’ yn golygu bod siawns o lifogydd o rhwng 1 mewn 1000 (0.1%) ac 1 mewn 100 (1%) bob blwyddyn mewn ardal.
Ar gyfer y Môr:
Mae risg ‘Uchel’ yn golygu bod siawns o lifogydd o fwy nag 1 mewn 30 (3.3%) bob blwyddyn yn yr ardal hon.
Mae risg ‘Ganolig’ yn golygu bod siawns o lifogydd o rhwng 1 mewn 200 (0.5%) ac 1 mewn 30 (3.3%) bob blwyddyn mewn ardal.
Mae risg ‘Isel’ yn golygu bod siawns o lifogydd o rhwng 1 mewn 1000 (0.1%) ac 1 mewn 200 (0.5%) bob blwyddyn mewn ardal.
Mae'r asesiad risg yn ystyried effaith amddiffynfeydd rhag llifogydd pan fo gennym wybodaeth. Mae amddiffynfeydd rhag llifogydd yn lleihau llifogydd, ond nid ydynt yn atal y siawns o lifogydd yn gyfan gwbl oherwydd gall dŵr fynd drostynt neu gallant fethu.
Mae gwybodaeth perygl llifogydd ar gyfer pob ffynhonnell wedi'i chreu fel 'croen nionyn', h.y. heb unrhyw ddata sy'n gorgyffwrdd rhwng bandiau risg unigol. Dylid cyfuno'r bandiau risg hyn a'u harddangos fel un haen ar gyfer pob ffynhonnell llifogydd.
Os dangosir data ar ffurf mapiau i eraill, dylid defnyddio graddfeydd map priodol o ystyried natur ddangosol y modelu. Dylid ei ddangos gyda graddfa chwyddo mwyaf o 1:5,000 a defnyddio mapio sylfaen o 1:10,000 i roi cyd-destun.
Mae'r mapio llifogydd yn seiliedig ar ardaloedd sydd mewn perygl o ddioddef llifogydd ac nid yw'n benodol ar gyfer eiddo unigol. Nid yw CNC yn cadw gwybodaeth am adeiladwaith eiddo unigol a allai effeithio ar ba un ai y gallai llifogydd o ddyfnder penodol fynd i mewn i eiddo ac achosi difrod. Mae ein gwybodaeth fel y cyfryw wedi'i chynhyrchu i nodi ardaloedd cyffredinol a allai fod mewn perygl o ddioddef llifogydd ar gyfer ymchwiliad pellach.
Cydraniad gofodol y data:
Modelu ar raddfa genedlaethol a wnaed gan ddefnyddio cydraniad grid o 2m.
Modelu ar raddfa leol a wnaed gan ddefnyddio gwahanol gydraniadau, yn nodweddiadol rhwng 2m – 10m.
Mae rhagor o wybodaeth ar gael yn adroddiad prosiect FRAW (2019) a thudalen we CNC Deall eich canlyniadau perygl llifogydd ( https://naturalresources.wales/flooding/managing-flood-risk/understanding-your-flood-risk-results?lang=cy ) i gael mwy o wybodaeth am ein data perygl llifogydd a sut y dylid ei ddefnyddio.
Mae'r Lefel Perygl dan Adolygiad yn nodi lleoliadau lle mae ein hasesiad risg o dan adolygiad dros y chwe mis nesaf oherwydd argaeledd gwybodaeth newydd o fodelau ar raddfa leol.
Datganiad priodoli
Yn cynnwys gwybodaeth Cyfoeth Naturiol Cymru © Cyfoeth Naturiol Cymru a hawl cronfa ddata. Cedwir pob hawl. Mae rhai nodweddion o'r wybodaeth hon yn seiliedig ar ddata gofodol digidol wedi'i drwyddedu gan Ganolfan Ecoleg a Hydroleg y DU © UKCEH DEFRA, y Swyddfa Dywydd ac Asiantaeth Afonydd yr Adran Amaethyddiaeth a Datblygu Gwledig © Hawlfraint y Goron. © Prifysgol Cranfield. © Sefydliad James Hutton. Yn cynnwys data OS © Hawlfraint y Goron a hawl cronfa ddata.
- Dull adnabod
- Rhychwant
- Dosbarthiad
- Ansawdd
- Allweddeiriau
- System Cyfeirio Gofodol
- Cynnwys
- Cyfyngiadau
- Cynnal a chadw
- Metadata
Dull adnabod
- Dynodydd
- NRW_DS124841
- Teitl Amgen
-
- Flood Risk from Surface Water and Small Watercourses
- Flood Risk from the Sea
- Flood Risk from Rivers
- Laith Metadata
- English
- Datganiad
-
For Rivers and Surface Water and Small Watercourses:
- ‘High’ risk means that each year, this area has a chance of flooding of greater than 1 in 30 (3.3%)
- ‘Medium’ risk means that each year, an area has a chance of flooding of between 1 in 100 (1%) and 1 in 30 (3.3%).
- ‘Low’ risk means that each year, an area has a chance of flooding of between 1 in 1000 (0.1%) and 1 in 100 (1%).
For the Sea:
- ‘High’ risk means that each year, this area has a chance of flooding of greater than 1 in 30 (3.3%)
- ‘Medium’ risk means that each year, an area has a chance of flooding of between 1 in 200 (0.5%) and 1 in 30 (3.3%).
- ‘Low’ risk means that each year, an area has a chance of flooding of between 1 in 1000 (0.1%) and 1 in 200 (0.5%)
The risk assessment takes into account the effect of flood defences where we have information. Flood defences reduce, but do not completely stop the chance of flooding as they can be overtopped or fail.
Flood risk information for each source has been created as ‘onion-skins’, i.e. with no overlapping data between individual risk bands. These risk bands should be combined and displayed a single layer for each flood source.
If data is displayed in map form to others, appropriate map scales should be used given the indicative nature of the modelling. It should be shown with a maximum zoom scale of 1:5,000 and that base mapping of 1:10,000 is used to give context.
The flood mapping is based on areas at risk of flooding and is not specific to individual properties. NRW doesn’t hold information about an individual property’s construction that might affect whether flooding of a certain depth could enter a property and cause damage. As such, our information has been produced to identify general areas potentially at risk of flooding for further investigation.
Spatial resolution of the data:
National scale modelling undertaken at 2m grid resolution. Local scale modelling undertaken at different resolutions, typically between 2m – 10m.
- Gwybodaeth ychwanegol
-
More information is available in the FRAW (2019) project report and NRWs Understanding your flood risk results webpage ( https://naturalresources.wales/flooding/managing-flood-risk/understanding-your-flood-risk-results?lang=en ) for more information on our flood risk data and how it should be used.
- Dyddiad cyfeirnod y set ddata (Cyhoeddiad)
- 2025-05-22
Ystod amser
- Dyddiad cychwyn
- 2018-09-01
- Categori pwnc
-
- Inland waters
- Environment
Rhychwant
Rhychwant
- Hyd
- Wales (WLS)
))
Dosbarthiad
Dosbarthiad
- Fformat - Math a Disgrifiad
-
-
Geographic Information System
(
Unknown
)
- Math
-
ESRI Feature Class
-
Geographic Information System
(
Unknown
)
- Lleolwr Adnoddau
- Download Data and Web Service ( WWW:LINK-1.0-http--link )
- Lleolwr Adnoddau
- Web Mapping Service ( OGC:WMS )
Ansawdd
Ansawdd Data
- Cwmpas Ansawdd
- Dataset
- Cydymffurfiad
- Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services
- Eglurhad
-
This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Gradd
- false
- Datganiad
-
For Rivers and Surface Water and Small Watercourses:
- ‘High’ risk means that each year, this area has a chance of flooding of greater than 1 in 30 (3.3%)
- ‘Medium’ risk means that each year, an area has a chance of flooding of between 1 in 100 (1%) and 1 in 30 (3.3%).
- ‘Low’ risk means that each year, an area has a chance of flooding of between 1 in 1000 (0.1%) and 1 in 100 (1%).
For the Sea:
- ‘High’ risk means that each year, this area has a chance of flooding of greater than 1 in 30 (3.3%)
- ‘Medium’ risk means that each year, an area has a chance of flooding of between 1 in 200 (0.5%) and 1 in 30 (3.3%).
- ‘Low’ risk means that each year, an area has a chance of flooding of between 1 in 1000 (0.1%) and 1 in 200 (0.5%)
The risk assessment takes into account the effect of flood defences where we have information. Flood defences reduce, but do not completely stop the chance of flooding as they can be overtopped or fail.
Flood risk information for each source has been created as ‘onion-skins’, i.e. with no overlapping data between individual risk bands. These risk bands should be combined and displayed a single layer for each flood source.
If data is displayed in map form to others, appropriate map scales should be used given the indicative nature of the modelling. It should be shown with a maximum zoom scale of 1:5,000 and that base mapping of 1:10,000 is used to give context.
The flood mapping is based on areas at risk of flooding and is not specific to individual properties. NRW doesn’t hold information about an individual property’s construction that might affect whether flooding of a certain depth could enter a property and cause damage. As such, our information has been produced to identify general areas potentially at risk of flooding for further investigation.
Spatial resolution of the data:
National scale modelling undertaken at 2m grid resolution. Local scale modelling undertaken at different resolutions, typically between 2m – 10m.
Allweddeiriau
Allweddair
- Math
- Theme
Dyfyniad
- Dyddiad (Cyhoeddiad)
- 2008-06-01
Allweddair
-
NRW Thesaurus
-
- flood risk
- flood modelling
- Math
- Theme
Dyfyniad
- Dyddiad (Cyhoeddiad)
- 2025-01-08
System Cyfeirio Gofodol
Cynnwys
Gwybodaeth Cynnwys
Proffil CNC
Elfennau CNC
Cyfyngiadau
Cyfyngiadau
Cyfyngiadau ar Fynediad a Defnydd Cyhoeddus
- Math o Gyfyngiad
- Other restrictions
Cyfarwyddeb Cyfyngiadau Mynediad
- Cyfyngiadau
- no limitations
Testun cyfyngiadau mynediad
- Cyfyngiadau eraill
-
There are no access restrictions on this data. NRW may release, publish or disseminate it freely.
Defnyddiwch gyfyngiadau
- Cyfyngiadau Defnyddio
- Other restrictions
- Cyfyngiadau eraill
-
© CNC/NRW and UKCEH. Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose.
Datganiad Priodoli
- Cyfyngiadau eraill
-
Contains Natural Resources Wales information © Natural Resources Wales and database right. All rights reserved. Some features of this information are based on digital spatial data licensed from the UK Centre for Ecology & Hydrology © UKCEH. Defra, Met Office and DARD Rivers Agency © Crown copyright. © Cranfield University. © James Hutton Institute. Contains OS data © Crown copyright and database right.
Math o Drwydded
- Cyfyngiadau eraill
- Open Government Licence
Metadata
Metadata
- Dynodydd Ffeil
- 4f4c4942-4343-5764-6473-313234383431 XML
- Laith Metadata
- English
- Math o adnodd
- Dataset
- Dyddiad Metadata
- 2025-05-22T11:32:20.662Z
- Enw Safonol Metadata
- NRW
- Fersiwn Metadata
-
1.0