Classification of the Persian Gulf Coastal Waters affected by Arvand river based on Trophic Index and Numerical Analysis

In order to characterize the trophic state of the Persian gulf coastal waters affected by Arvand river, trophic index (TRIX) as well as numerical analysis using cluster and discriminant were employed in this study. Chemical and biological parameters( NO3, NH4, TP, DO , BOD5) used in this study were collected seasonally from summer 2009 to spring 2010 (4 seasons). A new trophic index developed by modification of TRIX indicated oligotrophic to mesotrophic conditions for the Arvand river. Numerical analysis revealed three groups of the study area and it was found that the used methods are in good agreement. Both of them predicted good condition in the north of river and good to moderated in southern part of the study area and the numerical classification predicted same conditions in all of the river. However, TRIX was found to be a more accurate and suitable method. It performs more conservatively than the numerical classification and characterized lower classes of water quality for the stations in southern and northern parts of the study area.