Ireland’s hydrometric areas, used as management units for hydrological areas (EPA, OPW, ESBI, Local Authorities etc). They are made up of amalgamations of large river basins.

This data set contains estimates of naturalised river flow duration percentiles for Irish rivers. The flow estimates represent flows that could be expected in rivers under naturalised conditions and do not take account of artificial influences of any kind such as water supply abstractions or waste water discharges. The data set should be used in conjunction with the HYDRO Catchments layer to display contributing areas to each flow node. Data results include naturalised flow percentiles (NATQ1-99%), naturalised mean monthly flows (NATMMF1-12) and physical catchment descriptors. Flow estimates are provided in m3/second.