A comparison of water quality indices for coastal water.

The present article discusses and compares five different water quality indices, viz arithmetic water quality index, multiplicative water quality index, unweighted arithmetic water quality index, unweighted multiplicative water quality index, and Harkin's water quality index, which were considered for characterizing the coastal water quality at the Jawaharlal Nehru Port Trust, Bombay, India. Dissolved oxygen, pH, biochemical oxygen demand (BOD), temperature, suspended solid, and turbidity were used as the parameters of water quality indices. The value function graphs used for above-mentioned variables were developed using harbour water quality standards and aquatic life. The product moment correlation coefficients for various water quality indices were determined using the SPSS software package to evaluate correlation among various indices. It was found that the unweighted arithmetic water quality index was higher than weighted arithmetic water quality index while the multiplicative water quality index was lower than unweighted multiplicative water quality index. All the indices were well correlated with each other except Harkin's water quality index. The Harkin's water quality index was different from other water quality indices. The comparison of different form of indices showed that the multiplicative water quality index was the most suitable water quality index for coastal waters.