Short Duration Rainfall Extremes in Ireland: Influence of Climatic Variability

Abstract

Type of publicationArticle (peer-reviewed) A widely-noted change in the North Atlantic circulation in the 1970s affected the spatial distribution and seasonal pattern of rainfall over Ireland. To examine if this was accompanied by a change on short duration precipitation extremes, multidecadal time series from the second half of the twentieth century of thirteen hourly precipitation stations in Ireland have been analysed for the occurrence of extreme values over several durations of up to 24 hours. Strong evidence was found for a change since the late 1970s in short duration rainfall depths, particularly in the west of the country. Precipitation depth-duration-frequency analyses over two sub-periods showed that at several locations, storm event magnitudes which corresponded to a 30 year return period before 1975 had a return period close to 10 years in the post-1975 period. The widespread increase in spring and autumn rainfall and the local increases in the frequencies and magnitudes of severe rainfalls have implications for engineering hydrology, flood risk analysis and water resources management. The necessity of using up-to-date data to derive design storm magnitudes is stressed, due to the possible influence of underlying climatic shifts. Furthermore, as non-stationarity has been demonstrated, the use of long timeseries extending beyond thirty years into the past will result in underestimation of storm intensities in many areas.

Attribution of detected changes in streamflow using multiple working hypotheses

“…Similar responses in flood peaks have been reported elsewhere (e.g. Bree and Cunnane, 1979;Bailey and Bree, 1981;Lynn, 1981). Likewise, Wilcock and Wilcock (1995) examined the impacts of arterial drainage on the river Maine in Northern Ireland and found systematic increases in high flows.…”

“…The NAO influence in winter has subsequently been linked to extreme rainfalls (Maraun et al, 2011), winter runoff (Laizé and Hannah, 2010), high flows (Hannaford and Marsh, 2008) and enhanced orographic rainfall (Burt and Howden, 2013) in the British Isles. Similarly, Leahy and Kiely (2011) report an increase in March and October hourly rainfall in 1975 across Ireland, with a corresponding decrease in July rainfall. These changes are concurrent with a shift in the winter NAO index to a more positive phase.…”

Coupling distributed stormwater collection and managed aquifer recharge: Field application and implications

“…Numerous studies have reported increasing precipitation intensity over the last century, including analyses of California, Europe, East Asia, and the Middle East (Tomozeiu et al, 2000;Lenderink and van Meijgaard, 2008;Leahy and Kiely, 2011;Tu and Chou, 2013;Furl et al, 2014;Ka zmierczak and Kotowski, 2014;Zhang and Cong, 2014;Zolina, 2014). A recent study of extreme precipitation in the San Francisco Bay Area, just north of the present study's field site, found that mean annual precipitation changed little in the last 120 years, whereas large storms became less frequent and more intense (Russo et al, 2013).…”

Dublin Ireland: a city addressing challenging water supply, management, and governance issues

“…In the case of Ireland, climate change is predicted to cause an increase in average summer/autumn temperatures toward the end of this century of 3.0 to 3.4°C and average precipitation amounts beyond 2060 are for autumns and winters to be wetter by 15% to 20% and for summers to be dryer by 10% to 18% (McElwain andSweeney 2003, Dunne et al 2008). Also expected are increases in the frequency of extreme flooding events (Leahy and Kiely 2011). Although regional differences are not very clear from the simulations, the largest increases in summer/ autumn temperatures and the largest decreases in summer precipitation are expected in the southeast and eastern parts of Ireland, which includes Dublin.…”