Using Remote Sensing to Evaluate Coastal Erosion in Bonny Island, Niger Delta, Nigeria

Abstract

Digital Shoreline Analysis System was used to determine shoreline changes in Bonny Island, Rivers state. Shoreline data were extracted from satellite imagery over thirty-five years (1990-2025). The basis of this study is to use Digital Shoreline Analysis System to determine erosion and accretion areas. The result reveals that the average erosion rate in the study area is 4.24 m/year and the accretion rate is 14.09 m/year along the Bonny Island shoreline. The mean shoreline length is 27967.43 m with a baseline length of 25839.22m and the area is classified into four zones to properly delineate area of erosion and accretion based on the five class of Linear regression rate, endpoint rate and weighted linear rate of which zone 1 contain very high erosion with an area of landmass 1542384 m² which is 31.1% of the study area. Zone II contain very high accretion with a land area of 1232096 m² with 24.88%, zone III has high accretion rate with an area of landmass 1165953.107 m² which is 23.54% of the study area and zone IV contain moderate accretion with land area 1011973.992 m² which is 20.43% of the total studied area. Out of four zones, zone I found to be eroding with 31.1% and zone II, III and IV contain accretion with 67.9%. Therefore, Coastal engineers, planners, and shoreline zone management authorities may find the map output more useful in developing appropriate management plans and regulations for the beach or coastal zones of the Bonny shoreline, as well as other coastal areas of the state with similar geographic circumstances.