Physiographic Units Level 3 1:250,000 Ireland (ROI) ITM

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The term Physiography can be described as a blending of “physical" and "geography". Physiographic Units show Ireland’s physical landscape divided into categories such as ‘Bedrock plain’ and ‘Flat to undulating sediments’. Areas are grouped based on bedrock geology (solid rock at or below the land surface), Quaternary (largely Ice Age) sediments and geomorphology (landforms). Digital Elevation Models (DEMs) and Aerial photography are also used. Three maps were made, each giving a different level of detail. The Level 1 map has 7 categories. These show bedrock landscapes at different heights above sea level such as mountains (more than 300 m), hills (100 to 300 m) and plains (less than 100 m). Sediment (sand, gravel and soil) landscapes are grouped by slopes, such as rolling (gentle hills), hummocky (small lumpy hills) and flat. The Level 2 map has 16 categories. These show bedrock landscapes with different texture (how rough or smooth it is) or rugosity (how wrinkly it is), depending on the bedrock type (e.g. granite bedrock evolves into rounded mountains or hills). Sediment (sand, gravel and soil) landscapes are grouped by the type of geological process shaping them eg (Drumlin and ribbed moraine topography).

The Level 3 map has 29 categories. This is the most complex and further categorises in a similar way to level 2. Areas were mapped at scales ranging from 1:30,000 to 1:100,000 (1cm on the map relates to 1km). The map is designed to be used at 1:250,000 scale (1cm on the map relates to 2.5km). It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas). This data is shown as polygons. Each polygon has a unique identifier and its landscape category.

Data Resources (5)

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ESRI Shapefile
ESRI REST
ESRI REST
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Theme Science
Date released 2018-04-11
Date updated 2021-10-19
Dataset conforms to these standards The INSPIRE Directive or INSPIRE lays down a general framework for a Spatial Data Infrastructure (SDI) for the purposes of European Community environmental policies and policies or activities which may have an impact on the environment.
Rights notes ['Creative Commons Attribution 4.0 International (CC BY 4.0)', 'Data that is produced directly by the Geological Survey Ireland (GSI) is free for use under the conditions of Creative Commons Attribution 4.0 International license.\n\nhttps://creativecommons.org/licenses/by/4.0/\n\nhttps://creativecommons.org/licenses/by/4.0/legalcode\n\nUnder the CC-BY Licence, users must acknowledge the source of the Information in their product or application.\n\nPlease use this specific attribution statement: "Contains Irish Public Sector Data (Geological Survey Ireland) licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence".\n\nIn cases where it is not practical to use the statement users may include a URI or hyperlink to a resource that contains the required attribution statement.', 'license']
Update frequency Never
Language English
Landing page https://dcenr.maps.arcgis.com/apps/webappviewer/index.html?id=afa76a420fc54877843aca1bc075c62b
Geographic coverage in GeoJSON format {"type":"Polygon","coordinates":[[[-11.0, 50.0],[-11.0, 56.0], [-5.0, 56.0], [-5.0, 50.0], [-11.0, 50.0]]]}
Spatial Reference Systems (SRS) Irish Transverse Mercator (ITM, EPSG:2157)
Vertical Extent {"verticalDomainName": "sea level", "minVerticalExtent": "0", "maxVerticalExtent": "1041"}
Provenance information Visual analysis of four main digital data sources aided the construction of the national physiographic units map: (1) Geological Survey bedrock geology maps at 1:100,000 and 1:500,000 scale; (2) Geological Survey Quaternary sediments and geomorphology maps at 1: 50,000 scale; (3) Hydrographically corrected DEM with 20 m pixel size (EPA) and 5 m pixel size DEM (Ordnance Survey Ireland, OSI); (4) High resolution digitalglobe orthophotography dataset and national digital premium basemap map service cached from 1:4,000,000 to 1:1,000 scale (OSI). Quaternary sediments and geomorphology datasets, allied with the bedrock geology maps and the DEMs, enabled the differentiation of regions dominated by distinctive geomorphological features (e.g. drumlins, eskers, peat bogs, etc.). The analysis of these datasets was combined with slope, altitude and hill-shade maps generated from the DEMs, which permitted differentiating broad altitude thresholds and convex, concave and straight segments in slope. The defining elevation cut-offs between mountains, hills and lowlands are not universally standardised across the world, and this lack of a proper subdivision between these landscape sets also exists in Ireland. The threshold between mountain and hill adapted for this work follows work by the United Nations Environmental Programme (after Gardner, 1972), which defines a mountain as an “Elevation of at least 300 m, with a 300 m elevation range within 7 km” (Blyth et al, 2002). This threshold is unofficially reinforced in Ireland, by the digital 1:50,000 to 1:150,000 scale OSI topographic maps, which commonly indicate areas over 300 m as ‘mountains’. Although a systematic threshold for mountain cannot be determined from these maps, as some named mountains are lower than 300 m and some higher regions are not marked as such, 300 m is in most cases the minimum altitude reached by ‘mountains’ in Ireland. Landforms extending above the surrounding landscape often with a distinct summit ranging between 100 and 300 m altitude were classified as hills, to some extent in the Physiographic Units Map of Ireland Areas of lower elevation were generally characterized by the dominant sediment type within them, coupled with the dominant constituent landform (e.g. ribbed moraine, hummocky moraine, raised bog, etc.). The visual analysis of the datasets listed above within a GIS environment coupled with expert judgment was used to delineate the outline of the discrete physiographic units. The mapping delineation consisted of three main steps: (1) Production of physiographic unit maps for three pilot areas showing particularly differing landscapes (the Suir River catchment, the North Midlands drumlin belt and the western coastal stretch between Connemara and the mouth of the Shannon River) aiming to define a preliminary classification scheme. (2) Production of a nationwide map focusing on the delineation of physiographic units based on the DEM topography, Quaternary geomorphology, Quaternary sediments and bedrock datasets as listed above, followed by further development and definition of a more accurate classification scheme. (3) Merging and reclassification of physiographic units and editing of their outlines based on major changes on slope and altitude thresholds, as identified from slope and altitude maps constructed from DEMs. The data were digitized at scales ranging from 1:30,000 to 1:100,000 with the objective of generating a final dataset to be used at 1:250,000 scale. The use of a minimum physiographic unit size of 5 km2 was considered appropriate, an area of 5 km2 on the ground, cover approximately 0.8 cm An exception was made for islands less than 5 km2 as islands bigger than 0.1 km2 are included in the map. As well as this, five small physiographic units located along coastal areas showing particularly differing landscape character from the neighboring units were also allowed as exceptions. It should be noted that the resulting physiographic units map is designed for general information and broad-scale planning usage. The boundaries are based on the interpretation of the datasets listed above, on many instances local details had to be generalised to fit the map scale. Characterization of the physical landscape at a larger scale will require further and more exhaustive assessment, and may frequently require of site investigation. The map was created using ArcGIS software. In 2021, the data structure was reviewed and a new database was created in ArcGIS Enterprise. Using ArcGIS Pro 2.6.3, the dataset was renamed as part of a GSI data standardisation process. A standardised dataset alias was added. A unique id field was added. A new unique identifier was added for each record using an attribute rule. The Physiographic Class field was renamed and an alias added. A domain was created for the field to ensure attribute integrity for that field. The attribute values can only be added from pre-defined GSI tables. All existing attributes and the geometry were checked. Metadata was updated to the new GSI standard based on INSPIRE and ISO standards.