February 14, 2014

expert reaction to continued flooding

Further reaction to the ongoing flooding and storm conditions hitting the UK, with a focus on hydrology and flood forecasting. All SMC output on flooding here. 

Prof Richard Harding, Science Director, Centre of Ecology and Hydrology, said:

“The weather in the last two months has been exceptional.  It has been characterised by frequent rain systems tracking across the south of Britain, often associated with high winds.   In January the rainfall totals were locally 300% above average and over 200% over a large part of southern England.  The result of this relentless rainfall has been that soils and underlying aquifers are now full and the rivers and wetlands have more water flowing through them than has been observed for many decades.   

“The repeated passage of storms over England has been caused by a persistent Jet stream to the south of its usual position.  This persistence may be linked to the reduction of sea ice in the arctic or warm sub-tropical sea temperatures.  We have observed in the last five decades a rise in temperatures and an increase in the amount of water vapour in the atmosphere – these almost inevitably lead to an intensification of storms and increases in rainfall.  Indeed we have observed an increase in the intensity of rainfall in this period. The last two decades have also brought exceptional extremes in our rivers and groundwater– with floods in 2000/01, 2002/3, 2007, 20011/12 and now 2013/14 interspersed with droughts in 2003 and 2011/12.   All these trends are entirely consistent with the effects of increasing CO2 in the atmosphere.

“In the short term the saturated nature of the ground means that rivers and low lying areas are very vulnerable to flooding.  In the longer term this exceptional weather and extensive floods highlights that we are going to have to adapt to much more variability and extremes in the future.” 

Dr Nick Reynard, Science Area Lead for Natural Hazards, Centre for Ecology & Hydrology, said:

“After the devastating summer floods of 2007 the Pitt Review carefully analysed all aspects of how this country prepares for and deals with flooding. Post Pitt there have been two key developments in the implementation of flood forecasting science to better predict both the risks and impact of flood events. The first is the development of the Flood Forecasting Centre, which combines meteorological and hydrological expertise to provide forecasts for all natural forms of flooding – river, surface water, tidal/coastal and groundwater. River flow forecasting is underpinned by the Grid 2 Grid model developed by the Centre for Ecology & Hydrology.

“The second significant development has been an increased focus on surface water flooding – many of the 55,000 homes affected in 2007 were flooded by a surface water event. Surface water flooding is a key focus of the recently formed Natural Hazards Partnership, which provides information, advice and analysis to government and emergency responders across the UK in the preparation, response and review of natural hazards, and brings together expertise from across the UK’s leading public sector agencies and research institutes.”

Terry Marsh, Leader of the National Hydrological Monitoring Programme, Centre for Ecology & Hydrology, said:

“The tempestuous weather affecting the UK has continued through the first two weeks of February 2014. It appears likely that winter rainfall totals across much of Southern Britain will be the highest on record (in the NCIC series from 1910). As a result river flows have continued to increase in parts of the country, most notably in the Thames and the Severn basins. In recent days on the Thames river flows are approaching or have exceeded maxima recorded in the last major event (November 1974). The high river flows have led to extensive floodplain inundations aggravated by groundwater flooding in many vulnerable parts of the catchment.”