Major floods increased in temperate climates but decreased elsewhere, say researchers

Posted: March 12, 2021 by oldbrew in climate, research, weather
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Such floods, or lack of them, were ’caused by a range of factors’ so not conducive to any particular brand of alarmism, it would seem.
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Severe river floods are escalating in temperate climates and putting at risk populations, livelihoods and property, according to evidence published today in Geophysical Research Letters by an Oxford-led international team, says Phys.org.

The first global examination of recent changes in the size, frequency, and probability of extreme river floods using historical river records, the paper shows that dangers of extreme river flooding demand close monitoring of rivers for decades to come, to understand and account for the potential impact of such changes.

Dr. Louise Slater, the main author and Oxford expert in flood risks, warns, “Our work shows the magnitude and frequency of floods are changing substantially in different climates of the globe. Flood maps need to be regularly updated to keep up with these changes and protect people and their livelihoods.”

She maintains, “These changes cannot be ignored. We need to keep monitoring our rivers because long-term records are necessary to understand and communicate how major floods are changing relative to the past.”‘

Using historic recorded magnitudes of river flow, the team found that overall, floods have mostly decreased at the global scale.

In arid, tropical, polar, and cold climate zones, 20-year floods decreased between −33% and −12% on average since the 1970s. This was most visible in regions such as north eastern Brazil, eastern Europe, parts of western US and parts of northern China.

The team suggests these decreases may be caused by a range of factors such as flood control measures, climate changes and decreasing soil moisture, where drier antecedent conditions offset flood magnitudes (due to increasing temperatures, decreasing rainfall, or groundwater depletion).

Full article here.

Research letter: Global Changes in 20‐year, 50‐year and 100‐year River Floods

Comments
  1. saighdear says:

    waiting for the weather to clear: “decreased elsewhere” – would do , wouldn’t it – Areas of drought ( deserts & High latitudes / altitudes with LOW temps aka frozen areas) and as for Major floods …. caused by …? poor drainage or what then?

  2. oldbrew says:

    They admit long-term analysis is limited by lack of data.

  3. Since 1970 there has been considerable urbanisation, flood defences and concreting over of catchment areas. That is why river levels are higher in some places

  4. ivan says:

    Another thing that must be taken into consideration is the stupid green activists aversion to do such things a dredging of rivers to maintain their depth, we see the same thing in the lack of forest management leading to larger wildfires.

    There wouldn’t be all these problems if the greens and ecoloons got out of the way and let the adults run things as they need to be run.

  5. Curious George says:

    Floods decrease in “eastern Europe, parts of western US and parts of northern China”. And these are not “temperate climates”?
    Oxford used to be a good university. 😦

  6. oldbrew says:

    Floods are a sort of proxy for rainfall, but not accurate due to variable local conditions.

  7. Phoenix44 says:

    Over a 20 year period this is just random variation, perhaps with some local issues due to usage changes in some places.

    Flooding is always a local problem. If you want to actually help people you have to look locally, not globally.

  8. We used to have ‘River Keepers’ many years ago whose job it was to monitor and look after the health of the rivers and banks.

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