Water quality analysis of the rivers Topolnitsa and Luda Yana, Bulgaria using different indices

Abstract

This study focuses on the analysis of some of the worldwide use of surface water index estimates. The catchment areas of the two model basins of bulgarian rivers (Topolnitsa and Luda Yana) are subject to active anthropogenic load. There are numerous metallurgical plants, combines for non-ferrous metals, mines and tailing ponds have been operating in the area for many years. At the end the heavy metals being the final result of their production activity. In the same time the waters of the rivers have various applications - industrial, household and agricultural. To obtain an assessment of the water quality status of the Topolnitsa and Luda Yana rivers in Bulgaria, two different indices are used - Water Pollution Index (WPI) and the Bavarian Surface Quality Index - (CJ). In the first one the conditions are regulated by the creators of the algorithm (reference values, set of physicochemical indicators, requirements for the type of data), the rest are selected by the user according to criteria determined by him. The index is calculated by a number of physicochemical parameters as obligatory include “dissolved oxygen” and “BOD5”. This is due to the fact that these indicators are particularly sensitive to the anthropogenic impact. The CJ index presents a summary of water quality in a given sample according to a set of physicochemical indices and is expressed as a non-dimensional quantity from 0 to 100 (0 is the worst and 100 is the best water quality) grade of reference values are defined. In this index all conditions are set in advance by the creator, including the set of indicators, reference values, weight of individual indicators, etc. The dataset consists of analytical results from a 6-yrs survey conducted in selected points of the river systems. The main aim of this article is to test the sensitivity of two indices different in their construction, algorithm and content for complex assessment of river water quality in Bulgarian conditions.