Assessment of Shoreline Dynamics at Bonny Island, Nigeria using Geospatial Techniques

Abstract

Bonny Island is a highly dynamic one as there is a high level of interplay between the forces of erosion and accretion. From previous studies by the Nigerian Institute for Oceanography and Marine Research (NIOMR), the annual rate of erosion has been put at about 20 – 35 metres along the bonny shoreline. This claim was confirmed from the present study carried out along 12 transect points of 500 metres intervals along the Finima section of the Bonny beach. Geospatial techniques were used to carry out the assessment of the state of the bonny shoreline. Satellite imageries from 1976 – 2005 were used in the study and GPS receiver was also used to acquire the shoreline position along the transect points for 2011. From the result of the study, the Finima beach area was found to have the highest rate of shoreline dynamics. Erosion dominated in this area over accretion. This area experienced a total land area loss of 458.04 hectares of land out of which erosion and accretion recorded 280.47 and 177.57 hectares respectively. By this it means erosion claimed about 61.2% of the total land area while accretion recorded a 39.8% land increase. The changes were largely attributed to the presence of oil exploration activities as prior to the commencement of this anthropogenic activities there was lesser impacts of erosion as accretion predominated the area. There is therefore a cogent need to adopt some proactive measures to protect the bonny beach, from further land loss due to erosion and the untold hardship it brings to the coastal residents.