Water Quality Assessment Using Normalized Difference Index by Applying Remote Sensing Techniques: Case of Lake Nokoue

Abstract

The normalized difference indices are useful tools for monitoring water quality, assessing the health of aquatic ecosystems, and detecting changes in physicochemical parameter concentrations over time. They can be applied in various applications such as water resource management, water quality monitoring, and environmental research. The main objective of this study is to detect significant changes in turbidity and chlorophyll that may be due to environmental variations or other factors. Remote sensing techniques such as normalized difference indices have been applied to quantify turbidity (sediment concentration) and chlorophyll concentration observed from satellite images covering lake Nokoue. The satellite images used in this article are Sentinel2-SR images acquired at different dates and under different atmospheric conditions. All produced maps showed a pollution trend along the shores of lake Nokoue, with the center of the lake being less polluted. The normalized difference turbidity index (NDTI) of lake Nokoue ranges from -0.045 to 0.0723 depending on each point of the lake. As for the normalized difference chlorophyll index (NDCI), it varies from -0.016 to 0.019.