Quantifying Seasonal Variation of Water Quality in Littoral Lagoon Surface water using Geo-spatial Application

The livelihoods and health of inhabitants especially those closer to Lagoon environment as well as the ecosystems they depend on for survival are under risk due to the salinization of Lagoon surface water. This study examined seasonal difference of salinity / TDS concentration in Lagoon water body. The Lagoon is situated in South-west coastline area of Lagos state in Nigeria featuring infamously polluted water body due to its vulnerable location. Landsat 8-9 multispectral sensor bands (OLI & TIR) was employed for this investigation while single band combination algorithm such as NDSI, S1-1, SI-2 and EWI was used. Regression models were used to compare the value derived from real-time in situ measurements and the remote spatial data in order to validate the co-existence of the relationship. Regression model utilized both linear and non-linear equation. The linear testing revealed ( R 2 ) of 0.44 and 0.64 in wet and dry season in NDSI and TDS in situ. The non-linear equation performed equally better with coefficient ( R 2 ) of 0.52 and 0.69 wet and dry season. SI-1 vs salinity in situ revealed R 2 = 0.60 and 0.61 in non-linear equation. Similarly, NDSI mapping showed higher values of 7.9 in dry season, SI-1 records maximum value of 10.6, SI-2 reports maximum mapping of 9.6 suggesting higher concentration of salt content in dry season compared with wet season. The result however proved the effectiveness of utilized single band algorithm of Landsat 8-9.