Comparison of Dalmatian Water Evaluation Indices

Water quality in the Dalmatian waters of Southern Croatia was assessed using four different indices: an arithmetic index, arithmetic modified index, geometric modified index, and Solway-modified index. The waters were sampled 12 times during 1 year (from July 1998 to July 1999) at 50 sampling sites in Dalmatia. Nine water quality parameters were evaluated: temperature, mineralization, corrosion coefficient, dissolved oxygen, biochemical oxygen demand, total nitrogen, protein nitrogen, total phosphorus, and total coliform. A comparison of the indices showed that the arithmetic modified index and Solway modified index are relatively similar for high-quality water (i.e., they enable better discrimination between high- and low-quality water). Both indices, however, tend to yield a lower index number for low-quality waters.