Liou, Shiow-MeyShiow-MeyLiouLo, Shang-LienShang-LienLoWang, Shan-HsienShan-HsienWang2009-01-142018-06-282009-01-142018-06-28200401676369http://ntur.lib.ntu.edu.tw//handle/246246/96817https://www.scopus.com/inward/record.uri?eid=2-s2.0-3042644028&doi=10.1023%2fB%3aEMAS.0000031715.83752.a1&partnerID=40&md5=8bebb4227b0d25ddbfcebf7b942e9a65By exploring the behavior and limitations of conventional methods for quality evaluation, a better overall index for water quality in Taiwan and its application in Keya River are proposed. The thirteen variables are employed for the quality assessment. Numerical scales relating to the degree of quality are established for each variable to assess variations in quality and to convey findings in a comprehensive manner to others. The employed variables are categorized into three aspects referred to the principal components analysis, which are 'organics', 'particulates' and 'microorganisms'. The overall index consists of the geometric mean for the three defined aspects and multiplying by three coefficients, which reflect quality degrees of temperature, pH and toxicity, respectively. Besides, the arithmetic mean is addressed among the variables associated in the same aspect. Finally, a fresh, mixed aggregation function is developed for ensuring that the index score tells us something useful and does not hide important information. A case study of the Keya River is made to illustrate the application of this new index system. The new proposed index provides omprehensive information for water quality assessment, than the existing index used in Taiwan does. © 2004 Kluwer Academic Publishers.application/pdf163103 bytesapplication/pdfen-USAggregation function; Principal component; Rating curve; Water quality indexMicroorganisms; Particles (particulate matter); pH effects; Principal component analysis; Rivers; Toxicity; Mixed aggregation function; Water quality index; Water quality; organic compound; water; index method; principal component analysis; rating curve; river water; water quality; arithmetic; article; case study; controlled study; geometry; mathematical analysis; microorganism; nonhuman; particulate matter; pH measurement; principal component analysis; quality control; scoring system; Taiwan; toxicity; water quality; water temperature; Environmental Monitoring; Fresh Water; Hydrogen-Ion Concentration; Taiwan; Asia; Eurasia; Far East; Taiwanjournal article153271482-s2.0-3042644028http://ntur.lib.ntu.edu.tw/bitstream/246246/96817/1/42.pdf