ABSTRACT
In the past, many artisanal shelters and river ports were built at convenient locations, with little or no particular attention paid to such environmental factors as wave heights, sudden changes in water depths, uncharted reefs, currents, tidal streams, seaweed and mobile beaches (sand drift). Many of the structures were subsequently expanded and, in countless cases around the world, many of the problems that used to be considered minor have now developed into major ones, with some of these structures, for example, fouling up with seaweed or silting up (mouth facing the wrong direction) or just being inaccessible in rough weather (reefs too close to entrance channel).
A hydrographic survey, also known as a bathymetric survey, is therefore essential if the correct design decisions are to be made right from the project inception stage to ensure that the landing is easy to use and free of major maintenance problems under all conditions.
In this project, bathymetric and sidescan sonar surveys were conducted on Cybernetics Jetty area, Oghara in Delta State, Nigeria so as to assess water depths and to guide in providing and ensuring safe vessel movements in the jetty area and surrounding environment. The methodology involves the deployment of single beam echo-sounder and sweeping of the underwater by sidescan sonar (starfish) to determine the depth, topography and the presence of wreckages respectively and the use of CNAV DGPS GNSS system for positioning. Plans were prepared while summary, recommendation and conclusion were made thereafter.
