Mossaka FILLING AND PROTECTION PROJECTOF MOSSAKA’S BANKS The filling and protection campaign of Mossaka’s banks begins again this year. The difficulty of Mossaka Mossaka’s region of Central Cuvette is each year the object of more or less important floods. Areas are becoming inaccessible and the populations are then obliged to move by canoes. Therefore, over 110 inhabited hectares, 75 are flooded by the high waters of November, December and January and only 5 to 6 hectares are held harmless by the exceptional floods. The daily life of Mossaka’s inhabitants is rhythmed by the risks of rains. People are dying during the biggest floods. To this are added the numerous marshy areas which recover an important part of inhabited areas. Numerous diseases and insects are present in such places. The populations are then living in precarious sanitary conditions. 
Mossaka during rainy season To improve the daily life of such persons, numerous campaigns of dredging have been performed in the past. However, no visible result has been noticed in the time because the areas have been filled insufficiently. A real campaign should be realised in order to improve the life quality of Mossaka’s inhabitants. A Lasting solution A lasting solution might have been found. This is the objective in which the General Delegation of Great Works has signed a contract of Technical Research with SIAC Design Department. This research has allowed the development of a lasting solution consisting of an important fill as well as a protection for blanks of Mossaka. BCBTP has then approved the project. The Congolese State has charged GNCAC and CEA to realise it with the participation of SCEVN. Filling by Dredge working The final goal of the project is to re-raise the level of the isle to a fixed dimension. The quasi-totality of floods shall then be avoided. The method to re-raise the level of the isle is to pump sand accumulated in the river and bring it on the isle. This technique is called dredging. It is done with a ship, the dredge, which takes sand from the bed of the river with a powerful pump. This latter leads then a mixture of water and sand to the banks with big pipes. A small leakage of water joins then the river. The deposit areas are then levelled. Dredging of sand allows draining and cleaning up important areas where there were marshes previously. They are then clean and the inhabitants can build their houses on areas which are no more liable to flooding. During the dredge working, inhabitants are provisionally moved and all the security measures ensured. Protection of blanks The protection of blanks is going to allow the stabilisation of blanks and the retention of the sand discharged by the dredge. The leakage of water from the river creates erosion at the level of blanks. To protect them, a large bund shall surround Mossaka. A new concept adapted to specific constraints of the place has been implemented. Many techniques are used in order to constitute the bund. In the areas sustaining high hydraulic constraints, huge pipes filled of sands shall form the course. One or two pipes shall be superposed. We shall add thereon a sort of milfoil composed of successive layers of sand and wire – netting reinforced by a geotextile (polymer retaining sand and allowing water to pass through). In the areas sustaining less important hydraulic constraints, we shall only use the milfoil. Above these elements, panels of wire – nettings filled with stones shall come and protect the preceding elements from external attacks. Such bund adapted specifically for Mossaka shall surround the Isle and constitute the lasting solution in the time. 
Dike Illustration The works are expected to last 4 years. When they shall be completed, the inhabitants shall then be under the lee of bad weather.
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BUREAU D'ETUDES SIAC |
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G.N.C.A.C
B.P. 1155
Pointe-Noire, Congo
Tél: +242 94 03 63
Fax: +242 94 39 50
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Last update:
July 14. 2008 19:22:47 |
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