Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Journey back through time to help manage river floods

11.06.2003


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.


Close look

Historical records yield information on the damage caused by a river flood, how the emergency was managed and, sometimes, more technical data on water levels or river geometry. Palaeohydrologists may be called in to take a close look at the sediments and organic material in the flood plain and date the deposits. In the Ardeche area, they inspected caves to look for precious particulates loaded with information and count how many times the water level rose higher than the cave. Working from the historical shape of the river bed and a hydraulic model, the researchers built up streamflow data series and assessed the magnitude of each event. With these long series in hand, it was possible to compare different methods of estimating rare river floods and validate, on the Ardeche, the Gradex method used in France for assessing the safety of large dams.

Risk culture

A combination of hydrologist and historian is vital in addressing flooding so that the riparian population retain the memory of the risks involved. On the Saone river at Lyon, the researchers intend to make historical information available in the form of a column showing the present water level and the levels reached by the most extreme floods, together with the main vagaries of the river. This is in line with the new legislation on risk, making it a duty to mark flood levels on public buildings.

The historical data collected may also help in finding strategies for managing rare events, by optimising emergency plans and setting extreme flood levels more accurately. Methodological guidelines for technicians are being drafted jointly with the European countries taking part in the SPHERE programme.

Michel Lang | EurekAlert!
Further information:
http://www.cemagref.fr/Informations/Presse/indexgb.htm
http://www.lyon.cemagref.fr/hh/base-in/base_in_anglais/isere1859/presentation.htm

More articles from Ecology, The Environment and Conservation:

nachricht How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)

nachricht Quantifying the chemical effects of air pollutants on oxidative stress and human health
12.09.2016 | Max-Planck-Institut für Chemie

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Stronger turbine blades with molybdenum silicides

26.09.2016 | Materials Sciences

Scientists Find Twisting 3-D Raceway for Electrons in Nanoscale Crystal Slices

26.09.2016 | Materials Sciences

Lowering the Heat Makes New Materials Possible While Saving Energy

26.09.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>