Abstract:
The article presents the possibilities for combined application of heterogeneous indices for the assessment of the quality/pollution of river waters. For the purposes of the research, the so-called „open“, „partially open“ and „closed“ indices were used, which are different in their construction, algorithm and content, and include at least 10 physico-chemical indicators for assessment. Their sensitivity in regard to heterogeneous anthropogenic impact – industrial, domestic and agricultural – was tested. The obtained results testify that the evaluation indices applied in the article react in a different way to individual types of anthropogenic pressure, and in specific cases the selection of only one index could give incorrect results. The Canadian Water Quality Index (WQI) is most sensitive one, and to a significant extent the Water Pollution Index (WPI) also could be regarded as sensitive. The Bavarian pollution index is more suitable for checking primarily „domestic“ pollution, which limits its independent use. The results of the research make it possible to specifically reveal the spatio-temporal characteristics, forms and scales of the pressure on surface waters in the basins of the Topolnitsa and Luda Yana rivers, where various economic activities have been carried out for many years.