AIRBORNE OPTICAL DATA HARVESTING AND GEO-PROCESSING FOR WATER QUALITY RETRIEVAL OF LAKE MULARGIA

Satellite remote sensing provides valuable data for understanding spatial and temporal variability of water quality parameters. In particular, PRISMA and DESIS are showing increasing capabilities in water quality mapping even if further studies might be needed to fully exploit these relatively new data. In this context, high-resolution airborne hyperspectral sensors might support preliminary tests to evaluate satellite-based systems, while represent enhanced mapping tools. In the context of the H2020 PrimeWater project, this study presents the use of HySpex hyperspectral airborne data of the freshwater reservoir Mulargia (Italy) to: i) calibrate and validate algorithms to retrieve optically active parameters; ii) assess the feasibility of retrieve water quality parameters; iii) export of this knowledge on PRISMA and DESIS data. The Hyspex images were acquired on 24 September 2020 in coincidence with in situ data, both radiometric and water quality. HySpex data were geocoded with PARGE and atmospherically corrected with ATCOR code and the results showed a good consistency between water reflectance with in situ data. The retrieval of the optical properties from imagery was achieved with a spectral inversion of bio-optical modelling (namely BOMBER), parametrized with absorption and backscattering data of the site. The estimates matched well field data (r2> 0.8) and depicted the mesotrophic conditions of the reservoir with higher Total Suspended Matter in shallow coastal waters.