Assessment of Estuarine Shoreline Erosion Dynamics as Indicator of Sea-Level Rise Along the South–East Coast of Nigeria

Abstract

Saviour P. Udo-Akuaibit

Long-term field investigations to assess shoreline erosion were carried out on a sandy estuarine shoreline of Qua Iboe River estuary, South-East coast of Nigeria. An evaluation of shoreline maps and satellite imageries of 2002, 2013 and 2023 revealed a retrogradation of the estuarine shoreline at the updrift and downdrift estuarine beaches. Two areas of intense erosion at the downdrift estuarine beach which were noted in 2002 have been accreting from 2013 to the present, while on a major erosion site at the updrift estuarine beach noted in 2013 is still eroding to date. Alongshore grain-size pattern depicted very well-sorted fine-grained sand with no significant correlation with the erosion sites. Channel meandering processes in the estuary and low amplitude wave reflections from the shoreline may account for the estuarine shoreline morphodynamics. Erosion occurred around the meandering channel elbow close to the estuarine shoreline while accretion is attributed to the deflection of meandering channel processes away from the shoreline and accentuated by storm surge incident of 2011.The persistent chronic erosion along the updrift shoreline of the estuary over decades has displaced the coastal community landward and may be attributed to sea-level rise.

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