Extreme Rainfall Incidents Increasing In Parts Of UK
Pastor Dale Morgan
Extreme Rainfall Incidents Increasing In Parts Of UK*
Newcastle upon Tyne, UK (SPX) Sep 05, 2006
Extreme rainfall events - those likely to lead to flooding - have become
more frequent and intense over a 40-year period in parts of Britain,
particularly in Scotland and the North of England.
Scientists from Newcastle University, who analysed UK weather records
from 1961-2000, say the findings provide further evidence of climate
change occurring.
They also suggest that the 5 million people who live near to rivers -
ten per cent of the UK population - can expect to be flooded with
increasing regularity in the future which has implications for the
management of flooding and water resources.
Dr. Hayley Fowler, a member of the research team who will speak about
the project at the BA Festival of Science in Norwich on September 6*,
used records from the UK Met Office and the British Atmospheric Data Centre.
She and colleagues examined four distinct periods classed as 'extreme
rainfall events' ie where rain was observed to fall steadily over either
one, two, five or ten days. They found the probability of an extreme
five or ten day rainfall event during the 1990s, compared to the
previous 30 year period, increased by four times in Scotland and by two
times in Northern England.
The probability of an extreme rainfall event in South East England over
five and ten day events actually decreased by 1.5 times but further
analysis showed that this part of the country is experiencing a greater
frequency of smaller extreme rainfall events, and a change in the timing
of such events, with a greater frequency in autumn months. These still
pose a threat in terms of flooding because a greater amount of rain is
falling in total.
Additional analysis showed that extreme rainfall events that are
expected to happen every 50 years increased in frequency and size in
Scotland and Northern England, especially in the autumn.
Dr. Fowler compared the periods 1991-2000 with 1961-1990 for the
likelihood of 50-year extreme rainfall events. For an event that would
be expected only once every 50 years during 1961-1990, during the 1990s
this magnitude of event occurred once every eight years in Eastern
Scotland, once every 11 years in Southern Scotland, once every 25 years
in Northern Scotland, North West England and North East England.
In Central East England and Northern Ireland there has been no change.
However, in Southern England this type of event would now be expected
only once every 100 years.
The amount of rain falling in the UK for a 50-year event occurring over
five days rose by 12 per cent overall during the 40-year period examined
by the Newcastle University researchers, from 119.59 mm in 1961-90 to
134.17 mm in 1991-2000.
Yet a further breakdown of the figures for five-day rainfall events
showed a stark contrast between locations. In Scotland there was a 29
per cent increase in rainfall, from 131.72 mm in 1961-90 to 166.51 mm in
1991-2000; in Northern England, Northern Wales and Ireland there was a
nine per cent increase, from 119.64 in 1961-90 to 130.94 mm in
1991-2000. But in Southern England and Southern Wales there was a two
per cent decrease, from 107.42 mm in 1961-90 to 105.06 mm in 1991-2000.
The pattern of change in extremes uncovered by Dr. Fowler and colleagues
matches the predictions made in a number of models that estimate the
scale and speed of climate change over the next century.
Dr. Fowler, a senior research associate with Newcastle University's
School of Civil Engineering and Geosciences, said: "The changes we
observed over the 40-year period we studied are consistent with the
trend we would expect from global warming.
"If the trend continues, which is likely, this suggests we will have an
increase in flooding over the coming years which has major implications
for flood risk management."
Extreme rainfall, however, is just one factor contributing to the
increasing likelihood of flooding - other causes include increased
building on floodplains, changing land management practices and the
drainage of upland moorland.
Dr. Fowler added that water companies should consider ways in which they
can store water during extreme rainfall events for later use, probably
during the summer months which are expected to get drier over the coming
years.
"One solution could be to build storage facilities such as small
reservoirs close to rivers to catch the excess water following extreme
rainfall events," she said.
"This could also help alleviate the potential for flooding as well as
solve the water shortage crisis we are likely to experience in the
summer months."
Dr. Fowler, who is using the data to carry out an analysis of climate
change models and their potential reliability, now intends to delve
further back into weather records to observe trends over a longer period
of time.