Hello,
Reader of your site that I appreciate, I send you the following comment: "How to resolve the siltation of the dams?" Which foreshadows a Franco-Chinese collaboration. It was written by myself, Professor Levacher (University of Caen) and Philippe Dhervilly (Industrial specialist in sludge).
As you see fit, you can report it or put it online. Free to you!
Sincerely,
How to resolve siltation of dams?
Leaning on artificial lakes or reservoirs, a dam is a work of art promoting the regulation of the flow of a river, a river or a tide. Often it promotes crop irrigation. Sometimes it tempers the possibility of natural disasters, floods or floods. Under certain conditions, it authorizes the production of electricity. For a long time their construction celebrated a revenge on nature. "Today domesticated!" Exclaimed President Roosevelt as he launched the New Deal dam construction program. "Our country will never be the same again! »Enthused President Nasser at the inauguration of the one in Aswan. "China has conquered its river! »The Chinese authorities are trumpeting today.
With nature, arrogance is bad idiots! eillère. A dam is not a neutral infrastructure. Shaking up the environment, it changes the cycle and distribution of sediments. Trapped in fictitious spaces, their accumulation poses serious problems. In the case of coastal dams, this presence affects not only navigation channels but also fish spawning areas. These deposits have multiple repercussions such as the degradation of the water quality, the appearance of unsightly heap, the pressures linked to anthropogenic activities and finally the climatic signal. Celebrated as the only one of its kind, the fame of the Rance tidal barrage is now altered by the alarming siltation of its estuary. Another example, the Arzal dam, used com! reserves me drinking water, troubles the mouth of the Vilaine, leaving a siltation close to 22 million m3 of mud, that alone, almost 50% of that existing in the port area for mainland France. In China, the Three Gorges Dam, the largest in the world, could upset the ecosystem. Born of a diversion from the Chang Jiang River, the structure is structured around a reservoir with an area of 1084 km2. However the sedimentary evolution remains an unknown. What is more, in the absence of consolidation measures, sediments constitute a real danger in the event of a seismic event. In addition, downstream of large cities, they are sometimes contaminated. They therefore adversely affect the quality of the groundwater.
It is therefore no exaggeration to assert that the sustainability of dams depends on the solutions provided to the treatment of sediments. However, no sedimentary deposit can be reduced to a pre-established scientific model. Each dam maintains its own relationship with its environment. Only a hydro sedimentary examination manages to model it. Only here, to deliver reliable results, these studies must necessarily stretch in the! time. The phenomenon then worsens.
To combat the presence of sediment, to date, no solution is required. The technique of raising the dike is sometimes considered. According to some studies, it paradoxically accelerates the deposition of sediment. In the case of a coastal dam, these can be used for recharging nearby beaches. However, the option most often chosen consists of their immersion offshore. In appearance, this solution preserves the estuarine balances but it displaces the problem. Immersion operations can only be carried out taking into account the constraints of preserving the ecosystem. How then to take up the siltation problem head on, knowing that the evacuation of these low consolidation deposits is not easy. In addition, expensive and without return! economic. The solution could come from China. Confronted with the problem of siltation of its ports and estuaries, added to the unknown of the Three Gorges dam, China intends to provide an industrial response by recovering sediments as construction materials. First for dam construction, road backfilling but also for the manufacture of noble products, such as bricks. This approach associates industrialists with universities and research centers. For several years, civil engineering departments have been working on the mechanical performance of the vase. Zhejiang University in Hangzhou has developed a brick from the vases of its bordering lake. In Guangdong province, other processes are at work. Little by little, the technique is improving. This is not an innocent move. Complying with the new orientations of the National Popular Assembly, China now intends to become the laboratory of the world. In the field of new building materials, it takes advantage of the weakness of European research policy as well as the overly timid strategy of Western multinationals. And already, ahead of them. In addition, the enormous needs of its construction market favor this choice. Demand is pouring in, not only from China but also around the world. In the Maghreb, for example, Chinese expertise could provide solutions to certain heavily congested dams, such as those at Beni Amrane (Algeria) and Saboun (Morocco). Worried about the lost reserves! due to the silting up of the Aswan dam reservoirs! Egytians should also consult Chinese engineers. In France, the growing concerns of associations, linked to serious problems of siltation not only of dams but also on the coastal area, in particular, in port areas, impose a radical solution. The Franco-Chinese company Paneurochina intends to provide a global response to the treatment of sediments, resulting from dams or sea mud.
