The aquifer media layer is created by direct assignment of soil layer to S index values from 1-10. The majority of the pilot area (80 %) is covered by subsoils > 5 m thick, with further 10 % subsoils are > 3 m thick. The majority of the catchment is given the lower ‘S’-ratings due to soil and subsoil cover, with areas of little or no soil given a value of 10.

The Hydraulic conductivity layer is taken as a direct assignment of the hydraulic conductivities from the aquifer parameter database to the C index values according to DRASTIC, ranging from 1 to 10.

Vulnerability assessment output map using COP method

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

This factor takes into account the amount and frequency of precipitation in the study area. Annual average precipitation is fairly uniform across the pilot area and was assigned a value of 0.2. The average number of rainy days for this pilot is 225, which results in a low intensity value for for precipitation and an overall low reduction of protection ‘P’ score overall

This layer considers the nature and thickness of soils, subsoils, unsaturated zone confinement. The lowest values correspond to areas of karst aquifer with no overlying subsoil and the water table is at or near the surface. The highest values are for non karst rocks overlain by thick impermeable subsoils with a deep water table. The biggest influencing factor here was the presence and thickness of clay subsoil

I layer is calculated by direct assignment of vadose zone material to I index values according to DRASTIC methodology, raning from 1 to 10. In areas covered by subsoil deposits, the vadose zone media classification (the ‘I’-rating) was based on soil and subsoil type. In areas of exposed bedrock and subcrop or areas with < 3 m of subsoil coverage, the characteristics of the vadose zone was taken from the aquifer characteristics.

The D layer is the depth to the water table from the surface. The Boyne study area is based on 401 historical water level data points along with spring data and data from groundwater surface water interactions. Spatial interpolation using kriging was used and then the values were classified into the D index values. The highest D values correspond to where the water table is shallowest, generally found in the lower areas in the catchment, with the lowest D values meaning greater depth to the watertable, found in the upland areas

The aquifer media layer is created by calculation of the slope value from the national topographic data. S values were classified into DRASTIC S values from 1-10. Due the generally flat topography, the majority of the catchment is assigned the higher ‘T’-values.

The soil media layer is created by direct assignment of soil layer to S index values from 1-10. Rock outcrops frequently and there is little or no subsoil over much of teh catchment. The majority of the catchment is given the higher ‘S’-ratings due to lack of soil and subsoil cover, with areas of little or no soil given a value of 10.