The bi- or triennial conference series INTERCOH, initiated by Dr. Reg Parker and Prof. Ashish Mehta, offers an international platform where young, experienced and world leading scientists and engineers can meet and discuss the latest progress in the area of cohesive sediment properties, dynamics and modeling. INTERCOH is dedicated to improving our understanding of the physical processes of cohesive sediment in the natural environment. We invite contributions on the basis of theoretical and numerical studies, and on the basis of field and laboratory measurements. Contributions on chemico-biological processes affecting the physical behavior of cohesive sediment are also welcome.
The physical processes of cohesive sediment in the natural environment are still poorly understood, though research into this topic started a half a century ago. Yet, this understanding is important, as the earth’s surface is almost entirely covered with larger or smaller amounts of cohesive sediment, or mud as it generally known, with the exception perhaps of some deserts and some parts of the ocean seabed. It is, and has been throughout time, both a blessing and a curse to mankind:
- Cohesive sediment is a valuable resource. Civilization started in Egypt along the Nile River, in Mesopotamia along the Euphrates and Tigris, in India along the Indus, and in China along the Yellow River. All these areas were very fertile because of cohesive sediments deposited by the rivers on their flood plains. Also today, many river deltas belong to the most productive areas of the world, amongst which are the Yangtze delta, the Rhine-Meuse delta, and the Mississippi delta.
- Today, one realizes that cohesive sediment also plays a key role in the functioning of healthy eco-systems. It is indispensable for the development of flora and fauna in estuaries, on the seabed and on flood plains of rivers, and in particular for the natural evolution of healthy wetlands.
- Cohesive sediment is also a valuable resource of building and construction material, such as plaster and bricks.
- Unfortunately, cohesive sediment is often contaminated these days, as organic (pcb’s, etc.) and inorganic (heavy metals, etc.) pollutants adhere easily to the clay particles and organic material of the sediment. These contaminants can accumulate in the food web, sometimes to pathogenic and even lethal levels, endangering the entire eco-system.
- Because of the processes governing the transport and fate of cohesive sediment in open water systems, cohesive sediment tends to accumulate in still water regions, such as navigation channels and harbour basins. For instance, the Port of Rotterdam has to dredge about 10 Mm3 of sediment on an annual basis to safeguard navigation, whereas this amounts to about 3 Mm3 in the Port of Hamburg. Suffice it to say that the costs of maintaining these fairways and harbour basins can be very high, in particular when the sediments to be removed are contaminated.
- The management and lifetime of reservoirs may be affected largely by sediment input, which often has cohesive properties. The physical environment and eco-system downstream of reservoirs may be starved of fresh sediment input.
- Thick layers of cohesive sediment are found on the slope of continental shelves. These layers can become unstable because of natural (earthquakes, tsunami’s, gas releases, etc.) or human disturbance, as a result of which mudflows and/or turbidity currents are generated which may damage cables, pipelines, and sometimes exploration platforms.
Such mudflows are also found on land, in particular in mountainous areas, and their occurrence can be devastating.