Statistically, there is little likelihood of anybody experiencing a major river flood whose average recurrence interval is one hundred or one thousand years. Predicting and designing of such events involves going back in time, three or four centuries, by scrutinising records of severe flooding. Joint researches by Cemagref hydrologist Michel Lang and historian Denis Coeur have reconstructed the history of three French rivers, the Guiers, Isere and Ardeche, a unique picture which has been incorporated in the European SPHERE project involving French, German, Canadian, Spanish and Israeli teams.
esearch on three rivers
The search began with the Guiers, the historical boundary between France and Savoy. Using a qualitative recension of river floods, a list of the ten largest events recorded over the last 300 years was drawn up. Attention then turned to the Isere, to test the method on a river which had been extensively developed and controlled, and to see if the past could yield insights into the future. Four centuries of data was used. Contemporary eyewitness accounts are not ignored, and can be consulted on the Internet at http://www.lyon.cemagref.fr/hh/base-in/base_in_anglais/isere1859/presentation.htm where there is an illustrated account of the worst river flood, in 1859. The geography of the flood plain made it impossible to calculate river flow from water levels, because the flood plain is too wide and its contours insufficiently documented before the 19th century. Abundant information is available for the Ardeche river. Two sites were given special attention near the gorges, at Vallon Pont d’Arc and Saint Martin d’Ardeche. River flow has been recalculated from 1644 to the present. The largest river flood has been reconstituted with a 50% margin of error, which is comparable to today’s level of accuracy on high streamflows.
Michel Lang | EurekAlert!
How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie e.V.
Using drones to estimate crop damage by wild boars
12.12.2017 | Gesellschaft für Ökologie e.V.
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
13.12.2017 | Health and Medicine
13.12.2017 | Physics and Astronomy
13.12.2017 | Life Sciences