Surface water quality assessment using self-organizing maps and Hasse diagram technique

Abstract

The present study deals with the important issue of assessing surface water quality by the use of advanced multivariate data treatment approaches like self-organizing maps of Kohonen (SOM) and Hasse diagram technique (HDT). The object of the study is the catchment of the transboundary Mesta River on Bulgarian territory. Long-term monitoring data (1990–2009) were collected from all sampling sites along the river flow involving all major surface water quality parameters. The clustering of the data by the use of SOM has helped in their pre-processing for application of the HDT approach for ordering the sampling points according to the pre-selected set of water quality parameters describing the ecological status of the river in most reliable way. The ordering was obtained by the use of water quality norms according to the Bulgarian environmental legislation in order to assess in detail the water quality of the whole river system. Thus, the combination between two chemometric data treatment strategies and the national water quality norms made it possible to achieve a complete surface water quality expertise.