A Comparison of Water Quality Indices for Coastal Water

Abstract

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.

Avaliação da qualidade da água dos reservatórios localizados nas bacias hidrográficas dos rios Piauí – Real, utilizando o índice de qualidade da água (IQA)

“…São indicadores compostos, da qualidade da água que juntam as informações dos diferentes parâmetros de qualidade da água em um único valor global, que pode ser rapidamente e facilmente comunicado ao público-alvo (gestores, usuários e publico em geral). Os IQA apresentam a vantagem de diminuir o número de parâmetros associados que precisam ser interpretados para determinação da qualidade da água; permitem comparar estados de diferentes corpos de água, no intervalo espaço -tempo e são úteis para o planejamento de ações de gestão e aplicação de recursos financeiros [6,12,13,20).…”

Classification of the Caspian Sea coastal waters based on trophic index and numerical analysis

“…Coastal water quality issues can be studied if an accurate estimate of water quality is available in the form of an index for coastal waters (Swamee and Tyagi 2000). An index is a number, usually dimensionless, which expresses the relative magnitude of some complex phenomenon or condition (Gupta et al 2003). Several quality indices have been introduced in the last years for coastal water quality.…”

Statistical Tools for Analyzing Water Quality Data

“…This characteristic could be desirable when water quality indices are specific to the protection of aquatic life. However, when sensitivity to changes in each water quality parameter is more desirable than sensitivity to the most heavily weighted water quality parameter, such weighting could be unnecessary (Cude, 2001;Gupta et al, 2003;Landwehr & Deininger, 1976). Some unweighted water quality indices were therefore explored (Cude, 2001;Dojlido et al, 1994;Landwehr & Deininger, 1976) and are now introduced in the following subsection.…”

“…M is the number of water quality parameters plus the number of control values, t ij is the number of elements involved in the jth tie encountered when ordering the measured values of the ith water quality parameter, and k i is the total number of ties encountered in ranking the measurements of the ith parameter. Landwehr & Deininger (1976) and Gupta et al (2003) …”