Geospatial Analysis of Erelu Reservoir using Remote Sensing and Bathymetric Techniques in Oyo, Oyo State, Nigeria.

The research was conducted to provide information about the physical characteristics of Erelu reservoir in Oyo West Local Government Area, Oyo, in Oyo State. Data acquisition featured sounding by means of an echo sounder and for depth and position determination by means of a GPS while the tidal data used were based on existing data. Initial processing performed on the observed bathymetric data included; sorting with PowerNav and HYPACK 2018. Further processing was carried out 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 the digital shoreline analysis system (DSAS) was used for shoreline analysis. The results of the analysis showed that the maximum and minimum depths observed were 6.03m and 0.56m respectively 2023 an indication that the water is shallow. The surface area and volume values obtained were 120.94ha and 2975635.28943.13m3. Based on a linear and areal analysis, the bathymetric survey revealed that the maximum length and area reached in 2022 were 7855.171m and 84.506ha respectively, while the minimum length and area in 2017 were 7460.733m and 78.303ha respectively. Based on the results from DSAS, it was deduced that the accretion rate was high, while the erosion rate was minimal. Finally, the processed depths were analysed and presented in the form of charts, which may be used in the near future for planning and decision-making for proper management of the reservoir.