A study of twentieth‐century extreme rainfall events in the United Kingdom with implications for forecasting

Hand, William H.; Fox, Neil I.; Collier, C. G.

doi:10.1017/s1350482703001117

Cited by 98 publications

(86 citation statements)

References 9 publications

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“…Other rainfall extremes that impact the study area result from warm season severe convective rainfall events that yield intense winds, heavy rainfall and sometimes hail (and include tornadoes). Convective processes tend to account for extreme rainfall events of 2-6-h and shorter duration while synoptic events can dominate rainfall extremes for durations of around 12 h and longer (Hand et al 2004). Combinations of these synoptic and convective rainfall processes tend to bridge the durations and spatial scales between the two.…”

Section: Study Regionmentioning

confidence: 99%

Regionalization of heavy rainfall to improve climatic design values for infrastructure: case study in Southern Ontario, Canada

Paixao

Auld

Mirza

et al. 2011

Hydrological Sciences Journal

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Southern Ontario, Canada, has been impacted in recent years by many heavy rainfall and flooding events that have exceeded existing historical estimates of infrastructure design rainfall intensity-duration-frequency (IDF) values. These recent events and the limited number of short-duration recording raingauges have prompted the need to research the climatology of heavy rainfall events within the study area, review the existing design IDF methodologies, and evaluate alternative approaches to traditional point-based heavy rainfall IDF curves, such as regional IDF design values. The use of additional data and the regional frequency analysis methodology were explored for the study area, with the objective of validating identified clusters or homogeneous regions of extreme rainfall amounts through Ward's method. As the results illustrate, nine homogeneous regions were identified in Southern Ontario using the annual maximum series (AMS) for daily and 24-h rainfall data from climate and rateof-rainfall or tipping bucket raingauge (TBRG) stations, respectively. In most cases, the generalized extreme value and logistic distributions were identified as the statistical distributions that provide the best fit for the 24-h and sub-daily rainfall data in the study area. A connection was observed between extreme rainfall variability, temporal scale of heavy rainfall events and location of each homogeneous region. Moreover, the analysis indicated that scaling factors cannot be used reliably to estimate sub-daily and sub-hourly values from 24-and 1-h data in Southern Ontario.Key words heavy rainfall events; flooding; intensity-duration-frequency; regional frequency analysis; infrastructure design Régionalisation des fortes pluies afin d'améliorer l'estimation des pluies de projet pour la conception d'infrastructures: étude de cas dans le centre-sud de l'Ontario (Canada) Résumé Au cours des dernières années, le sud de l'Ontario (Canada), a subi les conséquences de nombreux épisodes de fortes pluies et d'inondations, qui ont dépassé les estimations historiques des valeurs des pluies de projet calculées par la méthode intensité-durée-fréquence (IDF). Ces épisodes récents, et le nombre limité de pluviographes enregistreurs à petit pas de temps, ont fait ressortir le besoin de revoir la climatologie des épisodes de fortes pluies dans la région étudiée, de revisiter les méthodologies IDF pour la conception, et d'envisager d'autres approches, comme des courbes IDF régionales, pouvant remplacer les courbes IDF ponctuelles traditionnelles. L'utilisation de la méthodologie d'analyse fréquentielle régionale a été évaluée pour le secteur d'étude, avec, comme objectif, la validation en termes de pluies extrêmes, des regroupements en régions homogènes déter-minées par la méthode de Ward. L'analyse a permis d'identifier neuf régions homogènes pour le sud de l'Ontario au moyen de séries de maximums annuels pour les données quotidiennes et horaires de la pluie provenant de stations climatiques et de stations de pluviomètres à augets basc...

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Section: Study Regionmentioning

confidence: 99%

Regionalization of heavy rainfall to improve climatic design values for infrastructure: case study in Southern Ontario, Canada

Paixao

Auld

Mirza

et al. 2011

Hydrological Sciences Journal

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show abstract

“…There are several criteria and arbitrary thresholds to define extreme precipitation events (Higgins et al, 2000;Zhang et al, 2002;Jones, 2000;Peña and Douglas, 2002;Lyon, 2003;Klein and Können, 2003;Burgueño et al, 2004 among others). Here, heavy rainfall is defined based on the duration and the intensity of precipitation (Hand et al, 2004). We chose a minimum period of four consecutive days to associate the extreme events with more persistent systems that can change the wind patterns in low level and within a larger spatial scale.…”

Section: Methodsmentioning

confidence: 99%

Rainfall variability in the rainy season of semiarid zone of northeast Brazil (NEB) and its relation to wind regime

Moscati¹,

Gan²

2006

Intl Journal of Climatology

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Abstract:The rainfall and the 850 hPa wind characteristic of the semiarid interior zone of the northeast Brazil (NEB) are analyzed. The database used are the daily mean u, v, z, T , q and θ , at 850 hPa, 500 hPa and 200 hPa, displayed on a 2.5°× 2.5°g rid, from the NCEP/NCAR reanalysis; the daily mean OLR data from the Climate Diagnostics Center, from June 1986 to December 1997; and the gridded daily precipitation (P) analysis data in Brazil (10°S-40°S and 30°W-80°W), produced by the Climate Prediction Center, from 1977 to 1997. Daily time series of the normalized rainfall index (RI) and the normalized 850 hPa wind indexes (i.e. zonal index (ZI), the meridional index (MI) and the u minus v index (UVI)) were calculated for northern (A1: 7°S-10°S and 37°W-44°W) and southern (A2: 10°S-15°S and 40°W-45°W) domains. The RI, ZI, MI and UVI were defined by area-average of P, u, v, and u minus v, divided by the number of grid points corresponding to each area, respectively. As for regional features this region presents a well-defined annual cycle of rainfall with rainy seasons from December to April in A1 and from November to March in A2, and a few extreme rainfall events (during a 20-year period, 26 cases occurred in A1 and 39 cases in A2). Several synoptic scale systems acting alone or simultaneously in the NEB could explain the occurrence of heavy rainfall in this region. The RI is correlated positively with both the ZI and the UVI, and negatively with the MI, which might indicate that when easterly and southerly winds intensify (weaken), the rainfall decreases (increases). From the statistical perspective the UVI appears to be more effective to describe the daily rainfall variability in the NEB semiarid interior region, compared to the ZI or MI.

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“…Intense, damaging convective rainstorms are therefore a rare but hardly unknown feature of the local climate. It is impossible, and possibly meaningless, to Jackson (1974Jackson ( , 1979 Collinge et al (1990) suggested that "… the reading is likely to be in excess of the true value, as a consequence of insplash, though not by much": the Hewenden Reservoir value -with a storm efficiency of 5.3 -was deemed 'not acceptable' in the Flood Studies Report (NERC 1975, p. 33) although both events were listed in a recent Met Office study by Hand et al (2004). attempt to assign accurate return periods to the extreme events of 16 August 2004, but the preliminary report of the Environment Agency into the flooding in Boscastle (Environment Agency 2005) indicated that the heaviest hourly rainfall had a return period of approximately 400 years and the 3 hour fall approximately 1300 years. It should be noted, however, that the return period of the resultant flooding (also assessed as approximately 400 years) bears only a coincidental relation to the return periods of the rainfall which caused it.…”

Section: How Rare An Event Was This Storm?mentioning

confidence: 99%

Cloudburst upon Hendraburnick Down: The Boscastle storm of 16 August 2004

Burt

2005

Weather

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A study of twentieth‐century extreme rainfall events in the United Kingdom with implications for forecasting

Abstract: Rainfall events in the United Kingdom during the twentieth century have been surveyed and those identified as extreme by the Flood Studies Report (1975)

Cited by 98 publications

References 9 publications

Regionalization of heavy rainfall to improve climatic design values for infrastructure: case study in Southern Ontario, Canada

Regionalization of heavy rainfall to improve climatic design values for infrastructure: case study in Southern Ontario, Canada

Rainfall variability in the rainy season of semiarid zone of northeast Brazil (NEB) and its relation to wind regime

Cloudburst upon Hendraburnick Down: The Boscastle storm of 16 August 2004

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