Based on the hydrogeological characteristics and on the value of the groundwater resource, all of the Republic of Ireland’s land surface is divided into nine aquifer categories (also described as resource protection areas). Eight aquifer categories are defined in Groundwater Protection Schemes (DELG/EPA/GSI, 1999), and they are as follows:
Regionally Important (R) Aquifers
· Karstified bedrock (Rk)
· Fissured bedrock (Rf)
· Extensive sand & gravel (Rg)
Locally Important (L) Aquifers
· Bedrock which is Generally Moderately Productive (Lm)
· Bedrock which is Moderately Productive only in Local Zones (Ll)
· Sand & gravel (Lg)
Poor (P) Aquifers
· Bedrock which is Generally Unproductive except for Local Zones (Pl)
· Bedrock which is Generally Unproductive (Pu)
During the course of National Aquifer Classification Programme (completed in 2004) undertaken for the Water Framework Directive, a further aquifer category was established:
Lk – locally important karstified bedrock.
Note that, depending on the degree and nature of the karstification, Regionally important karstified bedrock aquifers (Rk) may be further characterised as either Rkc – dominated by conduit flow or Rkd – dominated by diffuse flow.