Evolutionary trends of the Niger Delta shoreline during the last 100 years: Responses to rainfall and river discharge

There is growing evidence that the world river deltas are influenced by climate change and anthropogenic activities. In this study, shoreline changes along the Niger Delta coast of the Gulf of Guinea, North Atlantic Ocean in the last ten decades were investigated. The relationships between these changes and hydrometeorologic variables of rainfall and river discharge were considered. Topographic maps and satellite imagery, in addition to rainfall and hydrological data from the lower Niger River basin, were used for the study. The results show two distinct shoreline dynamics patterns/phases: first, mobility with high net retreat between 1923 and 1987 interval and; second, mobility with low net progradation from 1987 to 2013. During the first phase, shoreline retreat is mainly concentrated on the western and arcuate sections of the delta. In the second phase, all sections of the Niger Delta coast prograded seaward. Strong correlations between: shoreline change and the river discharge (R-2 = 0.95), shoreline change and rainfall variability (R-2 = 0.8), and rainfall variability and river discharge (R-2 = 0.63) further confirm that shoreline changes of the delta during the last 100 years have been influenced by the variations in river discharge and rainfall, which are ultimately driven by climate change. It is therefore concluded that shoreline changes during the last 100 years along the Niger Delta coast have been influenced by rainfall variability and the resultant river discharge variations, which are ultimately driven by the regional climate change. (C) 2015 Elsevier B.V. All rights reserved.