Groundwater Recharge 1:40,000 Ireland (ROI) ITM

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Groundwater is the water stored below ground in tiny cracks in the rock or in very small spaces between sand grains. It comes from rainwater that soaks into the ground into an aquifer. An aquifer is a body of rock and/or sediment that holds groundwater. The process of rain filling up an aquifer is called ‘recharge’. This is the Groundwater Recharge map. This shows where different amounts of rainfall reach the stores of groundwater (the ‘aquifers’) across Ireland. The estimated average annual recharge amount is shown in units of millimeters per year (mm/yr). The amount of recharge was figured over the period 1981-2010. This was then averaged to give a yearly amount.The map was created using the following datasets. Daily rainfall and daily potential evapotranspiration supplied by MetÉireann. Daily actual evapotranspiration for different soil drainage classes supplied by MÉRA/ICHEC. Groundwater vulnerability map supplied by GSI. Soil drainage map supplied by Teagasc. Generalised soil class map supplied by Teagasc/GWWG. Subsoil type map supplied by Teagasc/EPA & GSI. Subsoil permeability map supplied by GSI. Bedrock aquifer map supplied by GSI. Sand and gravel aquifer map supplied by GSI.The maps were overlain and interpreted to produce the groundwater recharge map for Ireland. This map is best displayed to the scale 1:40,000 (1cm on the map relates to a distance of 400m).It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas). The recharge data is shown as polygons. Each polygon holds information on:ID (Internal Use Only).Average Recharge (mm/yr) - average annual recharge to the groundwater aquifer across that polygon.Hydrogeological Setting - the hydrogeological setting code, which is determined by the combinations of different geological layers.Hydrogeological Setting Description – the description of the hydrogeological setting that determines its setting code.Recharge Coefficient (%) – the proportion of effective rainfall that becomes groundwater.Effective Rainfall – the rainwater remaining after plants have taken up some of the rainfall.Recharge (pre cap) mm/yr – effective rainfall x recharge coefficient, not limited by maximum recharge capacities.Recharge Cap Apply – is there a maximum amount of recharge that the aquifer can accept? (Yes/ No).Maximum Recharge Capacity (mm/yr) – the maximum amount of recharge the aquifer can accept. Only applies to bedrock aquifers of category Ll, Pl, or Pu.Recharge Symbology (Internal Use only) – the recharge map legend classes.Groundwater Vulnerability – the code for the groundwater vulnerability(Which shows land areas where groundwater can be easily contaminated. It also shows areas where it is very well protected by the natural subsoil layers) – X, E, H, M or L.Groundwater Vulnerability Description – the groundwater vulnerability description.Soil Drainage – whether the soil is well drained or poorly drained (Wet or Dry).IFS_CODE (Internal Use only) – Teagasc Irish Forest Soils project soil category code.Subsoil Type – the code for the subsoil type.Subsoil Description – description of the subsoil type.Sand and Gravel Subsoil (Internal Use only) – whether the subsoil is sand/gravel or not.Peat (Internal Use only) – whether the soil is peat or not peat.Subsoil Permeability - the code for the subsoil permeability (relative ease with which water can flow through geological layers)of the subsoil – L, M, H or N/A.Subsoil Permeability Description – description of the subsoil permeability - Low, Moderate, High or N/A. Depth to Bedrock (Internal Use only) – Depth from Surface to the top of the bedrock.Karst - extreme vulnerability area designated by a 30 m buffer around a karst landform feature such as a swallow hole, enclosed depression or spring, etc.Sinking stream - extreme vulnerability area designated by a 15 m or 30 m buffer either side of a river stretch that gradually sinks into an aquifer. The stream might sink gradually into the aquifer below, or be part of a river reach that sinks into an aquifer further downstream.Gravel Aquifer Category - the code for the sand/gravel aquifer category - Rg or Lg.Gravel Aquifer Description - description of the sand/gravel aquifer category - Regionally important sand/gravel aquifer or Locally important sand/gravel aquifer.Bedrock Aquifer Category - the code for the bedrock aquifer category - Rk, Rkc, Rkd, Rf, Lm, Lk, Ll, Pl or Pu.Bedrock Aquifer Description - description of the bedrock aquifer category.Bedrock Unit Name (Internal Use only) - the formation or member name of the bedrock geology.Bedrock Description (Internal Use only) - the description of the bedrock unit.Rock Unit Group - the hydrostratigraphic rock unit group that the bedrock is part of.County - the county the polygon is in.

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Theme Science
Date dataset released 2021-02-01
Date dataset 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. https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/legalcode Under the CC-BY Licence, users must acknowledge the source of the Information in their product or application. Please 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\". In 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,"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. https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/legalcode Under the CC-BY Licence, users must acknowledge the source of the Information in their product or application. Please 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\". In 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 Annual
Language English
Landing Page https://dcenr.maps.arcgis.com/apps/webappviewer/index.html?id=7e8a202301594687ab14629a10b748ef
Geographic coverage in GeoJSON format {"type":"Polygon","coordinates":[[[-10.47472, 51.44555],[-10.47472, 55.37999], [-6.01306, 55.37999], [-6.01306, 51.44555], [-10.47472, 51.44555]]]}
Spatial Reference Systems (SRS) Irish Transverse Mercator (ITM, EPSG:2157)
Vertical Extent {"maxVerticalExtent": "0", "verticalDomainName": "sea level", "minVerticalExtent": "0"}
Provenance information The groundwater recharge map shows estimated average annual recharge to the deep groundwater system. The ‘deep groundwater’ can be tapped steadily year-round and yields aren’t significantly influenced by seasonal changes. The recharge amount is shown in units of millimetres per year (mm/yr). The amount of recharge was calculated over the period 1981-2010 and then averaged to give a yearly amount. The main geological controls on groundwater recharge include soil drainage, subsoil type, subsoil permeability, subsoil thickness, and the ability of the underlying aquifer to accept percolating waters. The amount of rain falling on the land minus how much of that rain is taken up by plants is also a factor that determines how much groundwater recharge there is at a particular location. This is known as the ‘effective rainfall’. Different combinations of the geological factors give 24 hydrogeological scenarios. There is a ‘recharge coefficient’ for each scenario, which is the percentage of the ‘effective rainfall’ that may become groundwater recharge. Estimated groundwater recharge is lowest in areas overlain by thick, low permeability clay subsoil. Groundwater recharge is highest where there are coarse sand and gravels, which have high permeability, or where well-drained soils are thin or absent. Where locally important or poor fractured bedrock aquifers underlie the land surface, a maximum recharge acceptance capacity (‘recharge cap’) is applied, even where soils and subsoils are thin or absent. This is because these bedrock aquifers do not have enough fractures to store or transmit all of the percolating rainwater. In these settings, most of the groundwater recharge stays underground for only a short amount of time before it is ‘rejected’ and flows in nearby streams or ditches. Users of the map should be aware that for each hydrogeological scenario, the map uses the typical recharge coefficient from an available range. It also uses the 30 year average effective rainfall. This means that groundwater recharge may be over- or under-estimated, depending on local conditions. Users should also be aware that the recharge cap applied to poorly productive aquifers may need further examination for particular studies. In karst aquifers, groundwater resources may be overestimated due to low storage within these aquifers. Further possible limitations for particular areas are: only diffuse recharge is modelled and point recharge, or sinking streams are not accounted for in the groundwater recharge map; the influence of a shallow water table limiting recharge is not accounted for; ground slope is not accounted for. The map is derived from existing hydrogeological and hydrometeorological data layers: annual rainfall, annual estimated actual evapotranspiration (AE), soil drainage, subsoil permeability, groundwater vulnerability, peat, sand/gravel aquifer, bedrock aquifer class. The layers are overlain and interpreted using the guidelines (GW 5) outlined by the Irish Working Group on Groundwater (WGGW, 2005), subsequently revised in Hunter Williams et al. (2011) and Hunter Williams et al. (2013). The combination of hydrogeological layers gives a particular hydrogeological scenario that is related to a recharge coefficient. The recharge coefficient is the proportion of effective rainfall that can potentially become recharge. The map of recharge coefficients is combined with the effective rainfall map and the recharge cap to produce the groundwater recharge map. Application of the data: Local details are generalised to fit the original mapping and interpretation scale of 1:40,000. Evaluation of specific sites and circumstances will normally require further and more detailed assessments, and will often require site investigations. Phase 1: In 2008, Compass Informatics produced the first groundwater recharge map using the principles, hydrogeological scenarios and recharge coefficients outlined in WFD Guidance document GW5 (WGGW, 2005 - http://wfdireland.ie/Documents/Characterisation%20Report/Background%20Information/Review%20of%20Env%20Impacts/Groundwater%20Risk%20Assessment/GW5%20Abstraction%20Pressures.pdf) . The algorithm structure used by Compass Informatics is given in Groundwater Abstraction Pressure Assessment (Dublin City Council/ CDM, February 2009): http://wfdireland.ie/docs/24_Abstractions/Groundwater%20Abstractions%20February%202009%20ISSUE_v2.pdf . The processing was undertaken using ArcGIS and an avenue script. The projection was Irish National Grid (ING). Input data were: Teagasc/EPA 1:40,000 Subsoil Map; Teagasc/EPA soils 1:40,000; Soil drainage map with 4 classes – wet, dry, peat, made – based on Teagasc/EPA soils map; GSI 1:50,000 Subsoil Permeability Map from county GWPSs; Interim subsoil permeability map based on Teagasc/EPA maps; GSI 1:40,000 interim national groundwater vulnerability map; GSI 1:100,000 Bedrock Aquifer map; GSI 1:50,000 Sand and Gravel Aquifer map; Met Éireann 1971-2000 average annual Rainfall raster; Met Éireann 1971-2000 average annual Actual Evapotranspiration shapefile. Phase 2: In 2012, Geological Survey Ireland updated the groundwater recharge map to incorporate more extensive groundwater vulnerability and subsoil permeability mapping. Input data were: Teagasc/EPA 1:40,000 Subsoil Map; Teagasc/EPA soils 1:40,000; Soil drainage map with 4 classes – wet, dry, peat, made – based on Teagasc/EPA soils map; GSI 1:50,000 Subsoil Permeability Map from county GWPSs and NDP mapping; GSI 1:40,000 national groundwater vulnerability map based on county GWPS and NDP mapping; GSI 1:100,000 Bedrock Aquifer map; GSI 1:50,000 Sand and Gravel Aquifer map; Met Éireann 1971-2000 average annual Rainfall raster; Met Éireann 1971-2000 average annual Actual Evapotranspiration shapefile. Groundwater Recharge map creation technique: Created using tools built though ArcGIS model builder. On a county by county basis. In order for the Recharge map to be created, the recharge coefficient has to be calculated. This calculation depends on a large combination of conditions that are worked out from overlaying the following layers through a combination of unioning, intersecting, adding fields and calculating fields: 1. Teagasc Soils: For indicating areas of Peat and whether soil is wet or dry. 2. Teagasc Subsoils: For indicating sand and gravel soils. 3. Permeability 4. Vulnerability 5. Sand & Gravel Aquifers 6. National Bedrock Aquifer dataset 7. Effective Rainfall (Met Éireann). The Recharge Map Creation tool goes through several different geoprocessing tasks. For each county: 1. Selecting the county: Union the Teagasc soil, subsoil, Permeability and Vulnerability layers. 2. Unioning and intersecting with Fixed layers: -Intersecting Sand and Gravel Aquifer: This data will be included for analysis along with the Sand and Gravel soils from the Teagasc subsoils layer. -Intersecting National Aquifer: This layer will be used to calculate what cap (if any) will be applied to the potential recharge mm amount. -Aquifers of type Ll, Pu and Pl will entail a capping on this final recharge figure. (100 or 200 mm/yr) 3. A “hydrogeological scenario” category is applied according to combination of values for each record. A Recharge Coefficient is then calculated using the central value of the inner range of the recharge coefficients. 4. The final recharge value is calculated as Effective Rainfall x the %Recharge Coefficient. The projection was Irish National Grid (ING). For further Information see Hunter Williams et al. (2011) http://www.opw.ie/hydrology/data/speeches/08%20-%20Hunter%20Williams%20-%20National%20Groundwater%20Recharge%20Map.pdf Phase 3: In 2020, Geological Survey Ireland updated the groundwater recharge map to incorporate updated input maps: 1. hydrometeorological data produced by researchers at the Irish Centre for High End Computing (ICHEC) (Werner et al., 2019) ● MÉRA Daily rainfall in the period 1981-2010. Data source Met Éireann. ● Daily AE in the period 1981-2010. Three soil drainage classes. One reference crop type. Data source ICHEC (2019). ● 30 year average annual effective rainfall (mm/yr) derived from the preceding maps. 2. Teagasc soils drainage maps at 1:250,000 and 1:40,000 were combined ● Teagasc Indicative Soil Drainage map 1:250,000 (Creamer et al., 2016), recategorised to well-drained, moderately-drained and poorly-drained soils was used for the first time. Actual Evapotranspiration was estimated for each of these categories using Schulte et al. (2004) by ICHEC. ● A hybrid map was created by mapping indicative soil drainage categories onto the recategorised 1:40,000 soils map for the wet and dry soil categories. 3. Geological Survey Ireland updated maps: ● 2020 groundwater vulnerability, sand and gravel aquifer and subsoil permeability maps. In addition, the following improvements were made: ● better representation and improved recharge coefficients for peats (including cut, basin and fen peat); ● better representation of scree; ● additional scenarios for sand and gravel resulting in 24 hydrogeological scenarios. See Hunter Williams et al., upcoming Irish Groundwater Newsletter. The GIS code was re-written and the main updates are: ● A national grid (20674 grid squares) was created to allow for working on the data on a grid square by grid square basis - this allowed for testing before national rollout. ● Each national input dataset was clipped to each grid square. ● For each grid square, all inputs were unioned together. ● The hydrogeological scenarios and recharge coefficients were then applied to each individual polygon ● Each processed grid square was then merged together to create the national recharge map. The code was written in the Python language. QGIS provides a python API (Application Programming Interface) - PyQGIS. This API was used to process the data. Projection = Irish Transverse Mercator (ITM) Credits and references Irish WFD Groundwater Working Group (2002-2005) – Geological Survey Ireland: Donal Daly (Convenor), Geoff Wright, Vincent Fitzsimons, Coran Kelly, Taly Hunter Williams, Monica Lee; CDM: Henning Moe; Compass Informatics Ltd.: Paul Mills; Department of the Environment, Heritage and Local Government (DEHLG) Pat Duggan, Jim Ryan (NPWS), Aine O’Connor (NPWS); Environment and Heritage Service/ Geological Survey of Northern Ireland (EHS/GSNI): Peter McConvey; Environmental Protection Agency (EPA) Margaret Keegan, Micheal McCarthaigh; Kirk McClure Morton (KMM): Grace Glasgow, Kieran Fay; O’Callaghan Moran (OCM): Sean Moran, Gerry Baker; O’Neill Groundwater Engineering (OGE): Shane O’Neill; Shannon Pilot River Basin – EPA/TCD Research Fellow Garrett Kilroy; Southeastern River Basin District (SERBD): Colin Byrne; Teagasc: Karl Richards; Trinity College, Dublin (TCD): Paul Johnston, Catherine Coxon. Fitzsimons, V. and Misstear, B. (2006) Groundwater recharge through tills: uncertainties in applying soil moisture budgeting and river baseflow approaches in Ireland. Hydrogeology Journal, Vol 14, No. 4. Hunter Williams, N.H., Misstear, B.D.R, Daly, D. and Lee, M. (2013) Development of a of a national groundwater recharge map for the Republic of Ireland. Quarterly Journal of Engineering Geology and Hydrogeology, Vol. 46, No. 4. Schulte, R.P.O., Diamond, J., Finkele, K., Holden, N.M. and Brereton, A.J., 2005. Predicting the soil moisture conditions of Irish grasslands. Irish Journal of Agricultural and Food Research 44: 95–110. Werner, C., Nolan, P. and Naughton, O. (2019) High-resolution Gridded Datasets of Hydro-climate Indices for Ireland. 2016-W-DS-29. EPA Research Report Paul Mills, Compass Informatics – Phase 1 GIS Peter Cooney, GSI – Phase 2 GIS Shane Carey, GSI – Phase 3 GIS Robbie Meehan (An Talamh) for advice on optimum use of Teagasc soils maps (Phase 3) Shane Regan (NPWS) for advice on peat recharge coefficients (Phase 3)
Period of time covered (begin) 2008-10-14
Period of time covered (end) 2020-12-19

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