Fluvial Audit of the Afon Tywi
The Afon Tywi in Carmarthenshire is a large actively eroding river, designated as a Special Area of Conservation (SAC) for its migratory fish, and as a Site of Special Scientific Interest (SSSI) for various features including river habitat, river shingle invertebrates and little ringed plover. The river is unusually active in the middle reaches, sometimes moving as much as 50 m in a single year, and the various species for which the river is designated depend on the river remaining active.
In order to inform current and future river management, a fluvial audit of the past and present geomorophology of the Afon Tywi was carried out. This consists of a detailed technical report including identification of the most active river sections based on historic maps, a timeline of the river indicating key events such as major floods, and maps showing the geomorphology and sediment character of the river. Advice is also provided on the future sustainable management of the Tywi as an active shingle river.
This dataset consists of the results from the Fluvial Audit of the Afon Tywi which describes and spatially maps the past and present fluvial geomorphology of the Tywi catchment.
The aim of this data capture was to:
- Develop an understanding of the dynamic geomorphology of the Afon Tywi.
Specific aims include:
- Describe and map the fluvial geomorphology of the Tywi catchment past and present using a GIS system.
- Interpret the data gathered in the context of past and present human activity, including a risk assessment of consented activities.
- Provide advice on the future management of the Tywi SAC for use as a management and casework decision-making tool with regards to future bank reinforcement work, flood defence activities, aggregate extractions etc.
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS111562
- Metadata Language
- English
- Lineage
-
The project had numerous stages as follows:
Stage 1: Catchment Overview - literature study and GIS analysis of the catchment characteristics.
Stage 2: Hydrological Assessment.
Stage 3: The Fluvial Audit - Map and aerial photograph-based assessment; Field-based assessment; Detailed survey of sediment character; Linking map, field-based and laboratory results; Geomorphic impact of floods; Assessing sediment stores on the Afon Tywi; Impacts of human activity (including information from questionnaire of riparian users); Detailed analysis of case-study reaches.
Stage 4: Sensitivity assessment to help evaluate risk - Analysis of sediment balance at the points of gravel extraction; Strategy for assessing the impact of existing and potential gravel extraction.
Stage 5: Sediment transport modelling. Stage 6: Risk assessment and management advice.
- Dataset Reference Date (Publication)
- 1953-12-31
Temporal Extent
- Begin date
- 1890-01-01
- End date
- 1953-12-31
- Topic category
-
- Environment
- Inland waters
- Biota
Extent
Extent
- Geographic Extent
- Wales (WLS)
))
Distribution
Distribution
- Format Type and Description
-
-
Geographic Information System
(
Unknown
)
- Specification
-
GIS Data: MapInfo tables- Species data, Bank protection, Gravel extraction, Channel line
-
Documents
(
Unknown
)
- Specification
-
Report: Adobe Portable Document Format versions of Volume 1 and 3 of project report. Paper copy of all volumes- Volume 1: Technical Report; Volume 2: Maps Report; Volume 3: Short report for use by river managers.
-
Geographic Information System
(
Unknown
)
Quality
Data quality
- Quality Scope
- Dataset
- Conformity
- 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
- Explanation
-
This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Degree
- false
- Lineage
-
The project had numerous stages as follows:
Stage 1: Catchment Overview - literature study and GIS analysis of the catchment characteristics.
Stage 2: Hydrological Assessment.
Stage 3: The Fluvial Audit - Map and aerial photograph-based assessment; Field-based assessment; Detailed survey of sediment character; Linking map, field-based and laboratory results; Geomorphic impact of floods; Assessing sediment stores on the Afon Tywi; Impacts of human activity (including information from questionnaire of riparian users); Detailed analysis of case-study reaches.
Stage 4: Sensitivity assessment to help evaluate risk - Analysis of sediment balance at the points of gravel extraction; Strategy for assessing the impact of existing and potential gravel extraction.
Stage 5: Sediment transport modelling. Stage 6: Risk assessment and management advice.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
-
NRW Thesaurus
-
- coastal geomorphology
- Upper Reaches of Afon Tywi
- Special Areas of Conservation (SAC) (see also Candidate Special Areas of Conservation cSAC)
- fluvial
- fluvial geomorphology
- fluvial processes
- rivers (see also specific river names)
- river Tywi (afon Tywi)
- SSSI (Sites of Special Scientific Interest)
- Type
- Theme
Citation
- Date (Publication)
- 2026-08-27
Spatial Reference System
Content
Content Information
NRW Profile
Custom Elements
- NRW Related Title
-
A fluvial audit of the Afon Tywi : Volume 1 : technical report
- NRW Related Title
-
A fluvial audit of the Afon Tywi : Volume 2 : map volume
- NRW Related Title
-
A fluvial audit of the Afon Tywi : Volume 2 : map volume (addendum revised figure 16d)
- NRW Related Title
-
A fluvial audit of the Afon Tywi : Volume 3 : summary report
Constraints
Constraints
Limitations on Public Access and Use
- Restriction type
- Other restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
-
This dataset contains 'simple derived data' which is jointly owned by NRW and the Ordnance Survey in the form of river bank GIS layers (erosion, bank protection etc). NRW may release, publish or disseminate this dataset freely, providing recipients are made aware of use restrictions (see below). Data not derived from OS products have no access or use restrictions. Third party recipients may reproduce, disseminate and re-use this data free of charge in any format or medium, provided they do so accurately, acknowledging both the source and NRW's copyright, and do not use it in a misleading context. To avoid using old information, we recommend that the latest version is obtained from the original source.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
-
Third parties seeking to re-use this data require a OS Derived Data Licence issued by NRW. It allows re-use, reproduction and dissemination in any format or medium but only for non-commercial purposes, according to the terms and conditions of the Licence. Those seeking commercial re-use require a commercial licence available from the OS.
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313131353632 XML
- Metadata Language
- English
- Parent Identifier
-
Fluvial Audits of Welsh River Systems
NRW_DS101833
- Resource type
- Dataset
- Metadata Date
- 2026-09-29T10:59:25.186Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0