INTRODUCTION - Modelling Uncertainty in Flood Forecasting Systems - page 3

1.1.2 A reminder of a few recent floods
Floods are news (Ward, 1978)! Almost every year major flood events hit some parts on
earth. Dartmouth Flood Observatory (2003) has a chronological listing of major floods that
occurred since 1985. A few such flood events and the damages they caused are presented here.
In the United States, the great flood of 1993 is one of the more remarkable floods during
which 54,000 persons were evacuated, 50,000 homes were damaged and economic
losses of US$15-20 billion have been estimated. The event also tested the limits of the
nation's forecast and warning services as flood stages were exceeded at about 500 forecast
points. Between 1965 and 1985, floods accounted for 63% of the federally declared disas-
ters (337 out of 531), took 1,767 lives and caused US$5 billion worth of damage annually,
on average. The extent of the danger of floods in the United States is revealed by the fact
that there are 20,000 flood-prone communities: 3,000 of them receive site-specific flood
forecasts from the National Weather Service (NWS) and 1,000 have local warning sys-
tems; the remaining communities receive country-wide warnings (Krzysztofowicz, 1995).
Europe has also been severely affected by floods for centuries. As examples of recent
floods, in France 42 people died in 1992 during flash flooding in Vaison-la-Romaine;
basin-wide floods caused widespread disruption and losses in the Rhine and Meuse basins
in 1992, 1993 and 1995; and exceptional flooding struck the Po in 1994. In 1997 severe
flooding occurred in several parts of Europe, both as localised flash floods and as basin-
wide floods on major river systems causing loss of life, distress and disruption. The year
started with flash flooding in Athens in mid-January and then in July exceptional rainfall
in Czech Republic, Germany and Poland caused catastrophic flooding on the Oder River
killing over 100 people and laying waste vast areas of countryside. Again, in early November,
flash floods occurred, this time in Spain and Portugal with over 20 people losing their lives
(Samuels, 1999). Remarkable floods of August 2002 severely hit central Europe, particularly
many parts of Austria, Czech Republic and Germany with the losses of billions of euros.
Flooding is a major threat every year in many countries of Asia, including Bangladesh,
China, Japan, India, Nepal, Thailand, and Vietnam. In Nepal alone, not to mention the
social impact and property losses, 300 people die every year on average due to floods that
occur together with landslides and debris flows. The exceptional monsoon rainfall in the
year 2002 affected 46 of the 75 districts of Nepal including the capital city, 429 people
died (Dartmouth Flood Observatory, 2003) and hundreds of houses were swept away.
1.2 Flood management options
The traditional approach of providing protection against flooding is through the construc-
tion of huge and costly structures by which floodplains are protected from more frequent
inundation. Nowadays it has been widely realised that single objective flood “control” is