National scale potential recharge values for Ireland
The Groundwater Recharge map 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 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 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 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. This map is best displayed to the scale 1:40,000 (1cm on the map relates to a distance of 400m). 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
dataset
https://www.europe-geology.eu/tactic/ireland_lta_rech
English
Environment
GEMET - INSPIRE themes, version 1.0:
Spatial scope:
INSPIRE priority data set:
GeoERA Keyword Thesaurus:
European Geoscience Registry - Projects:
Free:
Groundwater; Potential recharge; Great Britain; Long term average;
-10.470,
51.444,
-5.372,
55.383
revision: 2020-06-30
min: 0.01
max: 8
CRS: Local - depth (http://www.opengis.net/def/crs/EPSG/0/1049)
grid
Geological Survey of Ireland (GSI)
email:
Taly.HunterWilliams@gsi.ie
Role: custodian
Data Quality
The map was created using the following datasets: daily rainfall, daily potential evapotranspiration (MetÉireann), daily actual evapotranspiration for different soil drainage classes (MÉRA/ICHEC), groundwater vulnerability map 1:40,000 (GSI), soil drainage 1:250,000 (Teagasc), generalised soil class 1:40,000 (Teagasc/GWWG), subsoil type 1:40,000 (Teagasc/EPA FIPS; GSI), subsoil permeability 1:40,000 (GSI), bedrock aquifer map 1:100,000 (GSI), sand and gravel aquifer map 1:40,000 (GSI). The map 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, 2013 and 2021). The combination of hydrogeological layers gives 24 hydrogeological scenarios that are then related to a recharge coefficient. The recharge coefficient is the proportion of effective rainfall that can potentially become groundwater recharge. The map of recharge coefficients is combined with the effective rainfall map and the recharge cap to produce the groundwater recharge map for Ireland. 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 potential groundwater recharge stays underground for only a short amount of time before it is ‘rejected’ and flows in nearby streams or ditches. Recharge values are estimated using: a lumped parameter forward modelling approach within a GIS. The model is uncalibrated, but recharge coefficients for different hydrogeological scenarios were constrained by using the results from several detailed studies that spanned a representative range of hydrogeological scenarios (see Hunter Williams et al., 2013 for details). Recharge values have been verified for some of the 24 scenarios, and produce acceptable water balances when used in catchment-scale assessments.
Constraints
Metadata about metadata
61193dfa-9da8-4370-a137-3db20a010833
Geological Survey of Ireland (GSI)
email:
Taly.HunterWilliams@gsi.ie
Role: point of contact
2022-04-04