R values are classified from 1 to 10. Groundwater recharge (GSI National Groundwater Recharge Map) varies between 14 mm/a and 573 mm/a across the Boyne catchment. Areas underlain by peat have the lowest groundwater recharge and lowest R values. The highest groundwater recharge occurs in areas where rock is at near the surface or the area is underlain by well drained soils and sand and gravels. These are assigned the highest ‘R’-values.
The GSI National Groundwater Recharge Map was reclassified as per DRASTIC methodology. It was created using ESRI ArcMap 10.5 and QGIS as a shapefile and converted into .tiff format