Chukwu Fidelis N.^1,, Badejo O.T.¹

Bathymetry is the study of under water depth of lake and ocean floors and accurate data for production of nautical chart is the main objective of bathymetric survey. This research work was conducted to investigate changes in the topography of the northern part of Lagos lagoon (Ikorodu route) and thereby updating the existing chart. Data acquisition was done using satellite imagery, tidal observation and reduction, depth sounding with echo sounder and GPS. Initial processing performed on observed bathymetric data includes spike removal, tidal correction on instantaneous depth and sorting with HYPACK 2008 software. Further processing was done using ArcGIS 10.0 Software. The processed depths were analyzed and presented in form of graphs and charts. A surface descriptor of sediment region for accretion and dredged region was developed using depth differential of two dataset and their sediment volumes were ascertained. From the analysis conducted, there is an indication that accreted sediment volume is greater than Dredged volume and perhaps could have being influenced by the adjoining tributaries of the lagoon water. For further studies, needs for investigating the source of accreted mass through integrated coastal management plan is recommended.

bathymetric survey, investigation, Lagos Lagoon, seabed, topographical changes