All six countries analysed in STAR-FLOOD – Belgium, England, France the Netherlands, Poland and Sweden – face the threat of flooding, but the mechanisms of flooding and the significance of the flood risk vary. The percentage of paved and built-up areas in Belgium is relatively high. This decreases the capacity of rainwater infiltration, resulting in a higher vulnerability to pluvial flooding. Although most recent events had predominantly a pluvial source, the most harmful events of the 20th century were caused by storms resulting in fluvial or coastal flooding (notably in 1953 and 1976). England has a high flood risk, with one in six properties being susceptible to fluvial, coastal and/or surface water flooding (Environment Agency 2009). With the impact of increased climate change, urbanisation, population growth and aging drainage systems this risk is increasing. In France about 60% of the natural disasters are floods and about 26% of the population (17 million people) is located in flood prone areas. These flood prone areas at risk from tidal flooding and storm surges (western and northern France), pluvial and flash floods (southern France), fluvial floods along the main rivers and pluvial flooding in most of the cities. Because major flood events in the 20th and 21st century have been relatively rare, risk awareness among the population is low.
Figure 1.1: Countries and cases analysed in STAR-FLOOD
In the Netherlands 26% is below mean sea-level and 59% is susceptible to flooding. 55% of the country is protected by embankments and dunes from tidal and river flooding. In 1953 a large flood disaster took place, resulting in over 1800 casualties in the Netherlands alone and also affecting Belgium and England. In reaction to this event, the Netherlands developed its Delta works, flood defences built to avoid another disaster of this scale. After the 1953 events no similar major events have occurred. There have been some threatening situations in 1993 and 1995 but no dikes were breached. Small scale pluvial flooding in urban areas also occurs as summer downpours are getting more intense due to climate change. Poland has a significant flood risk, with almost half of the municipalities endangered. In 1997 the Millennium floods affected about 2% of Poland’s territory inflicting a total damage of approximately €2.5 billion (1.7% of the GDP). The risk of flooding increases due to urbanisation and the resulting increase of impermeable surfaces. In 2010 heavy flooding occurred again in large parts of Central Europe, where Warsaw and other areas were heavily affected. Although projections of climate change in Central Europe are not clear in terms of change in mean annual precipitation, it is likely that the intensity of precipitation events will increase. Flood risks in Sweden are relatively small, although it is one of the largest countries in Europe, with a large variation in hydrological and geological conditions. Therefore, the probability and consequences of floods vary significantly. Fluvial floods are most common, which mainly occur as a result of heavy rains and snow melting. It is expected that in the Scandinavian countries temperatures will increase more than the estimated global average, and with this, the amount of intense precipitation events will rise.
Table 1.1: Types of flooding, number, costs and fatalities of flood events between 2002 and 2013 in the STAR-FLOOD countries (DG Environment 2014)
|Causes of flooding||No. of flood events 2002-2013||Total costs over all events 2002-2013 (extrapolated)||Total no. of fatalities 2002-2013|
|Belgium||Pluvial, fluvial, tidal, surge||10||€ 180 million||5|
|France||Pluvial, fluvial, flash floods||48||€ 8,700 million||152|
|Netherlands||Pluvial, fluvial, tidal, surge||3||€ 14 million||0|
|Poland||Pluvial, fluvial||10||€ 24,000 million||24|
|Sweden||Pluvial, fluvial, snow-melt||1||€ 320 million||0|
|United Kingdom||Pluvial, fluvial, tidal, surge, flash floods||48||€ 23,000 million||57|