TROPHIC CLASSIFICATION AND ECOSYSTEM CHECKING OF LAKES USING REMOTELY-SENSED INFORMATION

Both the conventional and the Carlson trophic state index (TSI) classi fication methods were employed to assess the eutrophication state of 2 6 lakes in the Norfolk Broads, UK. The parameters employed were: Secch i depth, chlorophyll a and total phosphorous which had been obtained p reviously by using Landsat TM imagery, ground reference data and empir ical algorithms for the Norfolk Broads (Baban, 1993). The conventional method did not provide sufficient differentiation between the Broads. The Carlson TSI provided sufficient information to differentiate betw een all 26 Broads. Consequently, using the Carlson TSI information, th ese Broads were classified into three groups. The classification was b ased on the relationship between the calculated Carlson TSI of the ext ernal phosphorous loading and its influence on the eutrophication proc ess as deduced from the calculated TSI values for the other two parame ters. The results were consistent with all the available knowledge and experience concerning these Broads and demonstrated the potential of combining remote sensing techniques and Carlson TSI in eutrophication assessment, ecosystem checking and watershed analysis.