Rainfall, where does it go?

The drainage from the airport is carried on small streams which run along ditches to the east of the airport. Kealys stream carries the water runoff from the longterm carparks. This is released into the stream slowly so as not to create major floods after storms. The result is a constant flood on the road from Kinsealy to the N32 as can be seen from the photos. Kealys stream flows into a lake at Kinsaley which drains by the Sluice stream into Baldoyle estuary. This stream is notable for having large stands of dangerous Giant Hogweed growing all along its banks and also along some roadsides near the stream.

These photos were taken after a dry spell of 2 weeks.
When a major rain event occurs Portmarnock and Malahide can be cut off from the rest of the county by floods on surrounding roads. These floods occur where each of these small streams is passing under a road. The gap under the road is overwhelmed by the airport runoff and overflows onto the road causing flooding.
This used to happen very occasionally but now occurs constantly.
Rainfall normally filters into the ground and flows downslope until it reaches a stream or river. When an area is paved like the airport runways, roads and carparks the water runs off to be collected in drains.
Because of the huge expanse of concrete a large amount of water flows off the airport. Water flowing off the concrete carries with it anything which has spilled from airplanes eg, aviation fuel overflow or anti icing fluid. The drains flow into the surrounding small streams. The Cukoo stream drains the southern carparks and flows into the Mayne. The Mayne river drains the south side of the airport and flows into the Baldoyle estuary.
It should be noted that the recent discoveries of illegal dumping along the N32 will probably have led to leaching of pollution into the Mayne river.
The Sluice stream is too small to be tested in the EPA survey but the Mayne is heavily polluted according to the reports on the EPA web site.
Pictures on this page show flooding on roads into and out of Portmarnock.