Shannon River Basin
The Shannon River Basin consists of the area containing Ireland's longest river, the River Shannon, and all of its tributaries and lakes. The official Ordnance Survey Ireland length of the Shannon from its Shannon Pot source is 224 miles (360.5 km) made up of 63.5 miles (102.2 km) tidal water flow and 160.5 miles (258.3 km) freshwater flow.
The Shannon Basin is Ireland's largest basin with an area of 11,700 km2. Including the estuary and the River Feale, the total catchment drains a total of 16,865 km2
It has a Long Term Average Flow of 208.1 m3/s (at Limerick City). This is double the flow rate of Ireland's second largest river, the River Corrib (104.8 m3/s). If the discharges from all of the rivers and streams into the Shannon Estuary (including the rivers Feale 34.6 m3/s, Maigue 15.6 m3/s, Fergus 25.7 m3/s, and Deel 7.4 m3/s) are added to the discharge at Limerick, the total discharge of the River Shannon at its mouth at Loop Head reaches 300m3/s.
The River Shannon is a traditional freshwater river for just 45% of its total length. Excluding the 63.5-mile tidal estuary from its total length of 224 miles, if one also excludes the lakes (L. Derg 24 mi, L. Ree 18 mi, L. Allen 7 mi plus L. Boderg, L. Bofin, L. Forbes, L. Corry) from the Shannon's freshwater flow of 160.5 miles, the Shannon as a freshwater river is only about 100 miles long.
The Shannon River Basin is part of the Shannon International River Basin District (SHIRBD) administrative area which has an area of (17,963 km2 in area) which, in addition to the Shannon Basin, also covers coastal parts of Kerry and Clare which drain to the sea. The SHIRBD contains 7,666 km of rivers, 1,220 km of coastline including estuaries, and 113 lakes including 53 over 50 ha in size. The main land use throughout the SHIRBD area is agriculture (70.7%). Peatlands (11.1%) and forestry (3.2%) are also important. The SHIRBD's population is 618,884 at 34 people/km2 (Census data 2002).
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