[A-OS15] Freshwater discharge through rivers and estuaries to the ocean

[AOS15-04] CHLOROPHYLL ESTIMATION OF LAKE AND COASTAL WATER USING REMOTE SENSING APPROACH

*Shweta Yadav¹, Yamashiki Yosuke¹, Junichi Susaki¹, Kanako Ishikawa², Yoh Yamashita¹ (1.Kyoto University, 2.LBERI)

Keywords:Chlorophyll-a, Lake and Coastal Water, Satellite-Remote Sensing

Chlorophyll-a is an optically active compound (OAC) commonly used as a proxy for phytoplankton biomass in an aquatic environment. Retrieving the concentration of chlorophyll-a remains a challenge due to the presence of several OAC particularly in water bodies which are in proximity to the land-based activities. In this study, an effort has been made to estimate the chlorophyll-a concentration of both the freshwater Lake Biwa and the coastal water of Wakasa Bay in Japan. A spectral decomposition algorithm was used to determine the chlorophyll-a using the satellite images. The algorithm was applied to the satellite images from two different sensors namely Landsat-8 /OLI and Sentinel-2A/MSI. The satellite-derived chlorophyll-a concentration for the lake and coastal water from two different sensors were compared to assess the performance of both the sensors. The accuracy of the chlorophyll-a results derived from the images was evaluated with the in-situ measurement data of the chlorophyll-a for the Lake Biwa and the coastal water of Wakasa Bay. Both satellite sensors appear to give the best results for the coastal water (R² > 0.80) with an RMSE < 0.3 µg/L. However, slight underestimation of chlorophyll-a noted for the Landsat-8 image with an increase in chlorophyll-a concentration. For the lake water, Sentinel-2A results were relatively better (R² > 0.70) than Landsat-8, with an RMSE of < 1.0 µg/L. The obtained results will be useful to evaluate the primary productivity of both freshwater and coastal water body.