groundwater-resources-bedrock-aquifers-1100000-ireland-roi-itm
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| Téama | Eolaíocht |
|---|---|
| Dáta eisithe | 2003-01-21 |
| Dáta nuashonraithe | 2021-10-22 |
| Cloíonn an tacar sonraí leis na caighdeáin seo | 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. |
| Nótaí Cearta | ['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'] |
| Minicíocht Nuashonraithe | Eile |
| Teanga | English |
| Lamairne | https://gsi.geodata.gov.ie/portal/apps/webappviewer/index.html?id=d333a8a9b6ab44378411fc0d973db4ef |
| Clúdach Geografach i bhformáid GeoJSON | {"type":"Polygon","coordinates":[[[-10.47472, 51.44555],[-10.47472, 55.37999], [-6.01306, 55.37999], [-6.01306, 51.44555], [-10.47472, 51.44555]]]} |
| SRS | Irish Transverse Mercator (ITM, EPSG:2157) |
| Méid Ingearach | {"verticalDomainName": "sea level", "minVerticalExtent": "0", "maxVerticalExtent": "0"} |
| Eolas Dualfhoinse | Bedrock Aquifers The process of assigning each aquifer to an appropriate category is termed ‘aquifer classification’. The detailed criteria and process can be found here: https://www.gsi.ie/en-ie/publications/Pages/GSI-aquifer-classification-flowchart.aspx. Bedrock aquifer classification is based firstly on the rock type (lithology), and the 1:100,000 simplified bedrock map is used as a basis. This dataset is called the Hydrostratigraphic Rock Unit Groups 1:100,000 Ireland (ROI) ITM, which was generalised to 27 hydrostratigraphic units. Yield is one of the main concerns in aquifer development projects, yields from existing wells are conceptually linked with the main aquifer categories: • Regionally important (R) aquifers should have (or be capable of having) a large number of ‘excellent’ yields: in excess of approximately 400 m3/d (4,000 gph). • Locally important (L) aquifers are capable of ‘good’ well yields 100-400 m3/d (1,000-4,000 gph). • Poor (P) aquifers would generally have ‘moderate’ or ‘low’ well yields - less than 100 m3/d. However, existing well yield information is often difficult to use because reliable, long term yield test data are quite rare (particularly for the less productive aquifers). In practice, then, the following criteria are used in aquifer classification: • Permeability and transmissivity data from formal pumping tests, where discharge and water levels readings have been taken over a period of many hours or days. • Productivity data from wells where either formal pumping tests have been undertaken or where at least one combined reading of discharge and drawdown data are available. The GSI has developed the concept of ‘productivity’ as a semi-quantitative method of utilising limited well test data (Wright, 2000). A ‘productivity index’ is assigned to a well from one of five classes: I (highest), II, III, IV, and V, using a graphical comparison of well discharge with specific capacity. • Occurrence of springs with ‘high’ flows (greater than 2160 m3/day total flow). • Occurrence of wells with ‘excellent’ yields (greater than 400 m3/day discharge). • Hydrological information such as drainage density where overlying strata are thin, and baseflows or flows in rivers (better aquifers will support higher baseflows and summer flows). • Lithological and/or structural characteristics of geological formations which indicate an ability to store and transmit water. Clean washed and sorted sands and gravels for example, are more permeable than poorly sorted glacial tills. Clean limestones are also more permeable than muddy limestones. Areas where folding and faulting has produced extensive joint systems tend to have higher permeabilities than areas where this has not occurred. • Aquifer assessments from Groundwater Protection Schemes in neighbouring counties and from existing reports. All seven factors are considered together; productivity and permeability data are only given ‘precedence’ over lithological and structural inferences where sufficient data are available. Data from neighbouring counties in similar geological environments are included. Some bedrock units have been grouped if they are of similar geological age and have similar lithological/structural characteristics. In considering the classifications provided, it is important to note that: • The bedrock aquifer classifications are based on the bedrock units mapped by the Bedrock Section of the Geological Survey Ireland at 1:100,000 scale - Bedrock Geology 1:100,000 Ireland (ROI) ITM There are seven bedrock aquifer categories: Regionally Important Aquifers: can support regionally important abstractions (e.g. large public water supplies), or give excellent yields (>400 m3/d). Bedrock aquifer units generally have a continuous area of >25 km2 and groundwater predominantly flows through fractures, fissures, joints or conduits. Regionally important sand/gravel aquifers are >10 km2, and groundwater flows between the sand and gravel grains. This group is subdivided into the following types: • Rk Regionally Important Karstified Bedrock Aquifer • Rf Regionally Important Fissured Bedrock Aquifer Regionally important karstified aquifers can be subdivided if it is known that groundwater flows mainly through conduits (Rkc) or more diffusely through solutionally-enlarged fissures (Rkd). Locally Important Aquifers: can support locally important abstractions (e.g. smaller public water supplies, group schemes), or give good yields (100-400 m3/d). In the bedrock aquifers, groundwater predominantly flows through fractures, fissures, joints or conduits. Locally important sand/gravel aquifers are typically >1 km2, and groundwater flows between the sand and gravel grains. This group is subdivided into the following types: • Lm Locally Important Bedrock Aquifer, Generally Moderately Productive • Ll Locally Important Bedrock Aquifer, Moderately Productive only in Local Zones • Lk Locally Important Karstified Bedrock Aquifer Poor Aquifers: are capable of sustaining small abstractions (e.g. domestic supplies, small group schemes), or moderate to low yields (<100 m3/d). Groundwater predominantly flows through a limited and poorly-connected network of fractures, fissures and joints. This group is subdivided into the following types: • Pl Poor Bedrock Aquifer, Generally Unproductive except in Local Zones • Pu Poor Bedrock Aquifer, Generally Unproductive All work on the data was carried out in ArcGIS. 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. Most fields were renamed and an alias added. Domains were created for relevant fields to ensure attribute integrity for those fields. The attribute values can only be added from pre-defined GSI tables in the form of drop-down values. Attribute rules were set up to automatically insert certain values eg unique identifier. The data was cleaned using a GSI notebook. This checked the attribute values contained valid domain values and a spell check was carried out. Some manual cleaning of obvious errors was also carried out. Metadata was updated to new GSI standard. Aquifer Geological Lines 1:100,000 Ireland (ROI) Originally, the lines were hand drawn on paper maps. All bedrock 100k map sheets (21) are available in paper copy accompanied by a geological report. Phase 1: The 21 paper maps covering Ireland were digitised. Each map was manually digitised using AutoCAD 12.0 software. Several layers of data were created for each map sheet: Stratigraphy, Lithology, Igneous, Diagenetic, Dynamic, Thermal, Linework and Point symbols and stored in .dwg format. The data was registered to the OSi 1:100,000 digital rasters. The data was clipped to the OSi coastline (high water mark). Water bodies such as lakes were also clipped. Irish National Grid (IG) projection. Phase 2: Data was converted to ArcInfo coverages (1994-2003) IG AutoCAD layers were converted to .dxf format and imported into ArcInfo 7.x. Coding was used to attach attribute information to the data layers from the bedrock lexicon table. A legend was generated. The ArcInfo coverages were converted to shapefiles. Phase 3: Borders and overlaps between map sheets were removed. IG. ArcGIS 8.x and Microsoft Access were used. Access was used to join additional attributes to the data layers including a unique code called NEWCODE. ArcGIS 8.x was used to manually remove borders and overlaps and to fill gaps. Work was carried out by GIS staff in close collaboration with bedrock geologists. The final product was quality checked by bedrock geologists. A stylefile was generated. Shapefiles produced were: 1) Final100kunion.shp - A polygon shapefile that contains bedrock geological information on Stratigraphy, Igneous, Lithology and Diagentic codes, their unit names and descriptions, 2) Index100Map.shp – A polygon index of 1:100,000 scale map sheets to allow sheet number identification at 100,000 scale. 3) Final100kstruc.shp (Structural Linework) - A line shapefile that contains structural geological linework codes and descriptions. 4) Final100kstra.shp (Stratigraphic Linework) - A line shapefile that contains stratigraphic geological line codes and descriptions. 5) Cross100ksection (Cross sections) - A line shapefile that contains map sheet cross sections as per paper printed maps and provides links to the cross sections in image format. 6) Final100kmin.shp - A point shapefile containing selected mineral and quarry descriptions from Bedrock 1:100,000 map series. 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. Most fields were renamed and an alias added. Domains were created for relevant fields to ensure attribute integrity for those fields. The attribute values can only be added from pre-defined GSI tables in the form of drop-down values. Attribute rules were set up to automatically insert certain values eg unique identifier. The data was cleaned using a GSI notebook. This checked the attribute values contained valid domain values and a spell check was carried out. Some manual cleaning of obvious errors was also carried out. Metadata was updated to new GSI standard. |
| Tréimhse ama clúdaithe (tús) | 2005-01-07 |
| Tréimhse ama clúdaithe (deireadh) | 2019-09-11 |
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