Geospatial Analysis of Erelu Reservoir Using Remote Sensing And Bathymetric Techniques in Oyo, Oyo State, Nigeria.

Abstract

The research was conducted to provide information about the physical characteristics of Erelu reservoir in Oyo west local government area Oyo, Oyo state. Data acquisition featured sounding with echo sounder and GPS for depth and position determination while tidal data used were based on an existing data. Initial processing performed on observed bathymetric data includes; sorting with PowerNav and HYPACK 2018. Further processing was done using ArcGIS 10.7 and SUFFER 2016 Software. The modified normalized difference water index (MNDWI) was used to extract the shoreline of the study area while digital shoreline analysis system (DSAS) was used for shoreline analysis. From the analysis conducted, the result showed that the maximum and minimum depths observed are 6.03m and 0.56m which is an indication that the water is shallow and the surface area and volume obtained are 120.94ha and 2975635.28943.13m3. The bathymetric survey result revealed that the maximum length and area reached was 7855.171m and 84.506ha in 2022 while the minimum area was 7460.733m and 78.303ha in 2017 based on linear and area analysis. It was also deduced based on the results from DSAS that the accretion rate was high while the erosion rate was minimal and finally the processed depths were analysed and presented in form of charts which may be used for planning and decision making in the near future for proper management of the reservoir.