Mapping the chlorophyll‐ a concentrations in hypereutrophic Krishnagiri Reservoir (India) using Landsat 8 Operational Land Imager

Krishnagiri Reservoir exhibits a hypereutrophic status and continuously receives external sediment and nutrient loads, in addition to its internal phosphorus loading, both affecting the reservoir water quality. Increased nutrient loading attributable to changing anthropogenic activities in the catchment area will further exacerbate the deteriorating trophic status. Temporal Satellite imageries can play a crucial role in the rapid assessment of the trophic status of the reservoir over a large spatial extent. The eutrophication status of freshwater systems is directly related to the chlorophyll‐ a (Chl‐ a ) concentration, which represents a major trophic state indicator by reflecting green and absorbing violet‐blue and orange‐red light of the solar energy spectrum. The present study was undertaken to map seasonal Chl‐ a concentration variations using Landsat 8 Operational Land Imager (OLI) images. Multiple regression equations developed using reflectance in the Green, Near Infrared, Shortwave Infrared 1 and 2 and Coastal bands ( R 2  = .635) were found to be the best fit of the model in mapping the Chl‐ a concentration variations in Krishnagiri Reservoir. The derived regression model also can be used to determine the trophic state of the reservoir and can facilitate a more rapid assessment for developing management strategies for sustainable reservoir water quality management.