Geoscience Reference
In-Depth Information
Himalayas and isolated tropical storms appear to have caused much of the problem.
Bring climate change factors into the picture and in the future flood problems will
undeniably be aggravated. If the recent climate events in Bangladesh are part of a
longer-term future trend, then arguably this future may have already begun. Indeed,
factor in the dimension of sea-level rise and matters will get worse still. As stated, the
region is low-lying and has previously seen damage from sea flooding. In the 1970
tropical storm some 300 000 perished when a tidal wave swept across the Ganges and
Meghina deltas (Burroughs, 1997). The implications are clear.
With regards to UK climate trends, the autumn 2000 was then the wettest since
records began in 1766. The heaviest rainfall that season was across England and
Wales, with a total of 489 mm falling between September and November; the most
extreme rainfall was in October, which resulted in extensive flooding that damaged
10 000 properties. UK insurance claims arising from that season's floods came to
around £1.3 billion. Many of the same areas of southern UK flooded again in early
2003. In the summer of 2004 a flash flood in Boscastle, Cornwall, was caused by
around 20 cm of rain falling in just 4 hours. Two rivers burst their banks and a 3
m wall of water passed along the town's high street. More than 150 people had to
be airlifted to safety and despite about 50-60 cars being washed away nobody died,
but around £50 million of damage was caused. Another extreme event took place in
January 2005, when 100 mm of rain fell around Carlisle in Cumbria. So intense was
the rain that surface-water drainage could not cope and flooding began quickly before
river monitoring (which the UK Environmental Agency then relied on) generated a
flood alert. The flood caused local power cuts and interrupted both the terrestrial and
mobile phone systems; consequently, some people became trapped in their homes.
The same year, 2005, saw a similar event on the North Yorkshire moors. After
a weekend heatwave in which temperatures reached 33.1
◦
C, the night of Sunday
19 June saw rainbursts over the north east of England that triggered regional flooding.
North Yorkshire as a whole had the best part of a month's worth of rain in 3 hours. One
fast-flowing flood that went through the villages of Thirlby, Helmsley and Hawnby
was caused by 2.7 cm of rain that fell in just 15 minutes. The flood was 2 m deep in
places and it carried cars along with it. Meanwhile, in river courses torrents washed
bridges away. The highest rainfall in the UK on that day took place in Hawarden,
Flintshire, in Wales, with 4.3 cm of rain. Two days after the event some 2500 homes
were still without electricity. Indicative of the 'clumping' of rainfall patterns Friday
24 June 2005 saw some 2.8 cm fall on RAF Lyneham in Wiltshire: the usual rainfall
for June in that area is 3-6 cm.
In 2007 three storms in June and July were of particular significance, the latter
two being the immediate cause of the most devastating of Britain's summer floods. A
distinguishing characteristic of the late spring and summer of 2007 was the frequency
and spatial extent of extreme rainfall events over a wide range of durations. Corres-
pondingly, the previous maximum May-July rainfall total in the 241-year England
and Wales series was exceeded by a wide margin; since 1879 no rainfall total in this
period has been within 100 mm of that for 2007. Widespread and severe flooding
afflicted many river basins in June and July 2007. In some areas - parts of the lower
Severn basin, headwater tributaries of the Thames, and Yorkshire and Humberside, in
particular - peak river flows exceeded previous recorded maxima by wide margins.
Search WWH ::
Custom Search