Development of an intuitive river-pollution index for prioritizing water quality management alternatives

This paper describes methodological development of an intuitive river-pollution index (RPI) to allow assessment of priorities for water quality management in a river basin. The proposed RPI improves upon existing approaches as it is directly linked to water quality criteria and designated water uses, and reflects the importance of different water uses in a given reach. The RPI ranges from 1 (ideal water quality) to 5 (worst water quality) for various water-use categories. Through this technique, two types of RPIs can be generated for a river basin: (a) an RPI for each water-use category and (b) weighted RPI. Following the development of the technique, concepts of plan efficiency index (PEI) and benefit/cost (B/C) ratio are introduced to make comparisons of management plans more intuitive. Applicability of the developed RPI is illustrated by applying to a number of examples. Reasonable results have been obtained demonstrating that the proposed RPI is a useful tool for not only rating water quality but also ranking management plans.