IDENTIFYING THE EUTROPHICATION STATUS OF SHALLOW WATERS BASED ON THE ESTIMATED TROPHIC STATE INDEX FROM SATELLITE DATA

Abstract

Remote sensing techniques have been widely used to measure the qualitative parameters of waterbodies. This work identifies the eutrophication status of 6 small and shallow lakes, including Hoan Kiem, Ba Mau, Bay Mau, Dam Tri, Truc Bach and Hai Ba Trung, in the Hanoiurban area using an empirical model developed from the in situ trophic state index (TSI) and Landsat 8 satellite data acquired on 21 September 2016 and 10 December 2016. The strong correlation between TSI values and the reflectance ratio of Landsat 8 band 3 versus band 2 (R2 = 0.69) allowed the quantification of the TSI by an exponential function (MSE = 0.04). Validation of the model for other water samples collected on the dates shows a high accuracy (R2 = 0.85; MSE = 0.4). Maps of TSI over the 6 lakes on the two dates surveyed clarified the eutrophication status of these lakes in autumn 2016 and demonstrate the trend in identifying the distribution of TSI from space. Study methods and data stated in this study confirm the high applicability of Landsat 8 satellite data for monitoring shallow lake eutrophication status.