New perspectives on Holocene flooding in Ireland using meta-analysis of fluvial radiocarbon dates

The last decade has seen advances in models of Holocene river flooding founded on meta-analysis of fluvial 14C databases allied to new multivariate environmental correlatives. This investigation presents application of these generic meta-analysis techniques to 33 stratigraphically significant ‘change after’ dates in a new fluvial 14C database for Ireland. Despite the relatively small number of 14C dates, the emerging pattern of Holocene flooding in Ireland corresponds closely to palaeoclimate proxies for regional temperature and precipitation, and to recently published results from a much larger British database. An underlying climate forcing of fluvial activity is proposed, although Irish ‘flooding episodes’ appear to lag those in Britain by ca. 100 to 300 years. This may be caused by 14C date precision and the embryonic nature of the Irish database, but could also reflect the respective effects of peatland cover and glacial inheritance on hydrological connectivity and sediment delivery resulting in a slower response of Irish rivers to climate events. These considerations, together with an increasing focus on regional variations in fluvial activity across the Holocene, will only be properly addressed with a more concerted and expanded programme of research in Ireland. Renewed research focus should seek to broaden the geographical coverage of 14C dated fluvial sites, with particular emphasis given to collaborative research of Irish lowland river catchments, especially where suitable palaeochannel and flood basin depositional contexts are present.