Canalization carried out during petroleum exploration is contributing to environmental changes in the Niger Delta. We carried out a study on five decades of canalization in Olero Creek, Benin River, from 1980 to 2020. The study site covered an area of 36.40 km2. Satellite imageries of five epochs (1980, 1990, 2000, 2010, and 2020) and Shuttle Radar Topographic Mission (SRTM) of 2000, which provided digital elevation models (DEMs) of the study area were collected and analyzed using ERDAS IMAGINE 9.2 and ArcGIS 10.6 software. We found that the total length of dredged canal increased from 14.14 km in 1980 to 61.07 km in 2020, spoil banks doubled from 2.05 km2 in 1980 to 4.13 km2 in 2020, and direct wetland loss doubled from 3.76 km2 in 1980 to 7.57 km2 in 2020, with the largest increase occurring between 1990 and 2000. The land use/land cover, topography, and hydrology of the area also changed. Water bodies that originally accounted for 1.17% of the study area in 1980, increased to 22% in 2020, Rhizophora racemosa fringing the waterbodies increased from 11% in 1980 to 47% in 2020, and Rhizophora mangle decreased from over 55% in 1980 to about 23% in 2020. The results of digital elevation model show that the surface area is undulating with the relative topography of the study site ranging from - 5 to 40 m. We conclude that canalization during petroleum exploration was contributing to land use, topographic, and hydrologic changes in the study area.
Keywords: Environmental changes; Mangrove; Undulating topography; Vegetation shift; Wetlands.
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