River floods

What is driving future fluvial flood risk in Europe?

Mainly exposure and to a lesser extent climate change are increasing flood risk by hundreds of percent this century. Measures reducing vulnerability can counterbalance this risk by only 15%.

Mixing signals of different catchments blurs climate-related trends in river floods

Increased extreme precipitation in recent decades has increased river floods globally. Previous studies failed to detect this because mixing catchments with different flood types blurred the results.

What is causing increased disaster losses, societal change or climate change?

Past economic losses by extreme weather events are not due to climate change. But ‘the times they are a changing‘. Today, many events do show a climate change fingerprint in loss and damage.

ClimateChangePost will join National Disasters Expo Singapore

On 7-8 December 2022, I will join the National Disasters Expo in Singapore, the world’s leading event for the management and mitigation of natural disasters.

In a changing climate, the 100-year flood event is a misleading concept

In a changing climate, concepts like the ‘100-year flood event’ are misleading. Return periods of floods are changing. Whether they increase or decrease, depends on climate zones.

Update 'Navigating rivers and deltas towards a sustainable future'

An update of the ‘River Basin Delta Tool’ is now online. The tool, first launched on the Climate Adaptation Summit 2021, shows effects of interventions on rivers and deltas and how to bend the trend.

The number of rivers that may flood at the same time is changing

The probability of multiple rivers flooding at the same time in Europe is changing. This often disregarded aspect is highly relevant for the capacities of disaster recovery and insurance companies.

Compound flooding in northwestern Europe: river and coastal floods are sometimes linked

Compound floods, simultaneous high water levels at the coast and in nearby rivers, have been relatively strong and frequent at times in parts of northwestern Europe. It’s not clear why.

No climate change impact on river discharge in Sweden

Dams are the dominant driver of changes in river flow in Sweden in the last half-century. Land use change has had a minor impact, and the impact of climate change is insignificant.

Annual maximum river flow is changing across Europe, probably due to climate change

River discharge observations across Europe for the period 1960-2010 show that annual maximum peak flow has increased in northwestern Europe, and decreased in southern and eastern Europe.

Areas in which nearby rivers flood at the same time are increasing in size

When rivers flood, nearby rivers often flood at the same time. The distance over which rivers flood simultaneously has increased since 1960. It far exceeds the size of individual drainage basins.

From 1.5°C to 2°C global warming nearly doubles the impact of river floods on human lives and economy

Most future projections of river flooding focus on vulnerability or exposure, and in direct economic damage. A recent study also presents estimates on numbers of casualties and welfare loss.

Global implications of 1.5 °C and 2 °C warmer worlds on extreme river flows

If we succeed in stabilizing global warming at 1.5 °C or 2.0 °C, the frequency of the current 1-in-100 year flow shifts to once in 70-90 years or once in 50 years, respectively, in most of the world.

Lower future river flood peaks in Northern and Southern Europe, for different reasons

Both in Southern and in Northern Europe river flood peaks will decrease. In the South as a result of a decrease in total annual precipitation, in the North due to less snowmelt.

No evidence so far of more major river floods due to climate change

Compelling evidence that the number of major river floods is increasing at a global scale is lacking. Generalizations about climate-driven changes in floods based upon previous studies are ungrounded.

Changing climate shifts timing of European river floods

The seasonal timing of river floods across Europe has been changing since 1960. Floods now occur earlier in northeastern and western Europe, and later around the North Sea and Mediterranean coast.

The ice regime of the rivers of European Russia changes, flood risk of ice dams too

The ice regime of Russia’s rivers changes in a complicated way. In the short term the hazard of ice jamming becomes less predictable. In the long term the risk of ice jam floods will decrease.

Seasonality high and low flows of the world’s largest rivers hardly shifts under climate change

Climate change doesn’t seem to shift the timing of high- and low-flow periods of large rivers between now and the end of the century. Current stream flow seasonality, however, seems to be amplified.

Strong increase global river flood risk may trigger large-scale crises

Even under the most optimistic scenario of global warming, global river flood risk more than doubles, stressing the need for timely and effective adaptation to control river flood risk.

Whether high or low flows of large rivers increase or decrease varies from one region to another

The world’s largest rivers are not equally sensitive to climate change. The Rhine, for instance, is not that sensitive to climate change, according to a recent assessment of extreme flows.

A dollar of flood damage hits poor and vulnerable people hardest

Poor and vulnerable people are insufficiently protected against floods. Investments in flood risk management are based on inadequate cost-benefit analyses with a too narrow focus on financial losses.

Flood peaks of Europe’s rivers will increase, unless driven by snowmelt

Whether a river’s catchment in winter is dominated by rainfall or snow determines the impact of climate change on its peak flows. The impact depends on how the ratio between rainfall and snow changes.

Recent flooding England and Wales not due to more intense rainfall

The flooding events over the last years do not seem to be related to changes in the magnitude of daily rainfall. It is the frequency of multi-day precipitation accumulations that has changed.

How to adapt to higher river flood peaks? Not (necessarily) by raising the dikes

Increasing the level of flood protection may be cost-effective, but is not sustainable in the long term. A higher level of flood protection results in the loss of flood memory.

Climate-related disaster risk increases, but not necessarily due to climate change

Increasing exposure to flooding is the main cause of the steeply rising trend in global river flood losses over the past decades.

Indeed David Cameron: climate change may have influenced England’s 2013/2014 winter floods

Is England’s winter flooding of 2013/2014 influenced by anthropogenic climate change? British Prime Minister David Cameron: ‘I very much suspect that it is’.

Changes in snowmelt affect flood peaks across in Britain

Changes in snowmelt affect the size and timing of flood peaks in Britain. Snow is a major component of flow for catchments particularly in Scotland.

Norwegian floods are changing: more rain, less snowmelt

less snow and more rain will change the magnitude and frequency of rainfall versus snowmelt driven floods in Norway. In fact, this is already happening.

What do we really know about our future flood risk?

Climate change will have an impact on river flood risk, but to what extent? One thing is clear: the impact is highly uncertain.

River flood risk in Europe under high-end climate scenarios

Estimates based on a combination of climate and flooding models indicate that river floods affect some 216,000 people every year in Europe. The estimated annual damage for Europe is 5.3 B€.

River flood damages under climate change in Germany

Total annual river flood damages in Germany sum up to nearly EUR 500 million per year for the current situation and, on average, double until the end of this century.

Trends in magnitude, frequency and timing of floods in Spain

An analysis of trends in magnitude, frequency and timing of floods was conducted at a national scale in Spain for the periods 1942–2009, 1949–2009 and 1959–2009.

Potential influences on the United Kingdom’s floods of winter 2013/14

Potential influences on the United Kingdom’s floods of winter 2013/14 have been assessed. Total winter rainfall in the Thames catchment in this winter was the highest on record.

Future flood risk Lech River Austria

Alpine countries suffered from economic losses of € 57 billion caused by natural hazards—only in the period from 1982 to 2005. The extensive flood in the Alpine region in August 2005