Creating sedimentation basins


A surplus of (fine) sediments in coastal waters, lakes, estuaries or waterways can pose challenges for overall water quality, navigation and water intake facilities. Sediment basins can help to mitigate these challenges. Sediment basins are strategically-located, deepened, below-water trenches or pits. The sedimentation basins create a low-energy zone where (fine) sediments can settle and deposit. Traditionally, local deepened areas are often constructed with the sole goal of facilitating maintenance dredging, concentrating accumulation of (fine) sediment within the pit and reducing sedimentation elsewhere. These so-called sediment pits or sediment traps do not decrease the maintenance dredging activities, but move the efforts towards a strategically chosen position. The Building with Nature (BwN) sedimentation basins concept strives on achieving an effect at system scale.

In this context, sedimentation basins are part of a larger system approach focusing on turbidity reduction, sediment management, overall habitat health and beneficial re-use of (fine) sediments and can be combined with other Building with Nature concepts (constructing nature islandsclay ripening and consolidation and stategically placing fine sediment). If the additional sedimentation in the basin is significant compared to the natural sedimentation in the vicinity, it will result in lower turbidity levels in the ecosystem in the long-term. The efficiency of this concept depends on the characteristics of the environment and the design of the sedimentation basins. Finally, this concept is introduced as a solution within non-coastal zones with low-energetic conditions. However, the concept is not limited to these zones and might also be applied in a different setting. In this concept the scientific basis, how-to guidelines and a practical applications example are given.