Remember this past winter and the wailing over the floods in the Somerset levels?
Catastrophic Floods of Dartmoor, South West England
The authors write that “extreme floods are the most widespread and often the most fatal type of natural hazard experienced in Europe, particularly in upland and mountainous areas,” noting that “these ‘flash flood’ type events are particularly dangerous because extreme rainfall totals in a short space of time can lead to very high flow velocities and little or no time for flood warning.” And “given the danger posed by extreme floods,” they say “there are concerns that catastrophic hydro-meteorological events could become more frequent in a warming world.”
What was done
In a study designed to see if such a trend may have established itself over the past several decades of climate-model-induced angst, Foulds et al. constructed “a high resolution record of flood activity on Dartmoor over the last ca 150 to 200 years using lichenometry,” thereby enabling “recent devastating floods in the South West of England to be placed in a more meaningful temporal context, which short-term instrumental data cannot provide.”
What was learned
The three UK researchers say their results show that Dartmoor experienced “widespread flooding, with particularly large and frequent events in the mid-to-late 19th and early 20th centuries,” while there has subsequently been “a general decline in flood magnitude that was particularly marked after the 1930s/mid-1940s,” which they indicate was “primarily due to a decrease in heavy rainfall events.”
What it means
From Foulds et al.’s point of view, as they express it in the concluding sentence of their paper, “the dangers of not accounting for historical flood frequency and magnitude may lead to an underestimate of flood risk,” which is clearly correct. In addition, it suggests that in response to 20th-century global warming, this extreme weather event (flooding due to heavy rainfall) became not more frequent and extreme, but less frequent and extreme, in total contradiction of what the world’s climate alarmists claim should be happening in response to global warming.
Source: CO2 Science (h/t to The Hockey Schtick via Twitter)
Foulds, S.A., Macklin, M.G. and Brewer, P.A. 2014. The chronology and the hydrometeorology of catastrophic floods on Dartmoor, South West England. Hydrological Processes 28: 3067-3087.
Extreme floods are the most widespread and often the most fatal type of natural hazard experienced in Europe, particularly in upland and mountainous areas. These ‘flash flood’ type events are particularly dangerous because extreme rainfall totals in a short space of time can lead to very high flow velocities and little or no time for flood warning. Given the danger posed by extreme floods, there are concerns that catastrophic hydrometeorological events could become more frequent in a warming world. However, analysis of longer term flood frequency is often limited by the use of short instrumental flow records (last 30–40 years) that do not adequately cover alternating flood-rich and flood-poor periods over the last 2 to 3 centuries. In contrast, this research extends the upland flood series of South West England (Dartmoor) back to ca AD 1800 using lichenometry. Results show that the period 1820 to mid-1940s was characterized by widespread flooding, with particularly large and frequent events in the mid-to-late 19th and early 20th centuries. Since ca 1850 to 1900, there has been a general decline in flood magnitude that was particularly marked after the 1930s/mid-1940s. Local meteorological records show that: (1) historical flood-rich periods on Dartmoor were associated with high annual, seasonal and daily rainfall totals in the last quarter of the 19th century and between 1910 and 1946, related to sub-decadal variability of the North Atlantic Oscillation and receipt of cyclonic and southerly weather types over the southwest peninsula; and (2) the incidence of heavy daily rainfall declined notably after 1946, similar to sedimentary archives of flooding. The peak period of flooding on Dartmoor predates the beginning of gauged flow records, which has practical implications for understanding and managing flood risk on rivers that drain Dartmoor.
Of course, a picture always says it better, as in “Dredge the flood channel, you idiots!”.