Environmental Consequences of Innovative Dredging in Coastal Lagoon for Beach Restoration pp. 219-248
Authors: (Emmanuel Lamptey, Department of Oceanography and Fisheries, University of Ghana, Legon, Ghana)
Abstract: Evidence suggests that hydraulic dredging is accompanied by considerable adverse environmental impacts on the receiving ecosystem especially on the benthos and water quality. Recently, innovative dredging is designed to minimise environmental impacts and enhance the ecological settings. Evaluations of environmental consequences of such innovative dredging are essential to quantify the ecological benefits and the associated impacts to ensure good environmental management. Congruently, innovative dredging (‗design with nature‘ principle) in a large tropical coastal lagoon in Ghana (Keta lagoon), West Africa, was assessed Before, During and After dredging operations on spatio-temporal scales to ascertain the environmental impacts on the macrobenthic fauna, shorebirds and water quality. A total of 9091 million cubic meter of sediment was removed from the 8m stretch of the lagoon for beach nourishment, land reclamation and creation of habitat islands. The macrobenthic fauna was sampled once in 2000 (Before), 2001 (During) and 2002 (After) along seven stations (A-0 to G-0 of 1-km interval) in the dredged channel. Water quality was assessed at the subsurface and bottom layers quarterly from June, 2001 to September, 2002. The shorebirds community abundance were quantified monthly from August 2000 to 2002, but only parallel data from August-December (peak periods of shorebirds abundance) of each year (2000-2002) was used for statistical analyses.