Environmental Engineering Reference
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important river basin in Eastern Thailand, using Scottish water quality indices.
They collected samples from June 1998 through 1999 at 11 monitoring stations
covering a total of 227 km of river path. The monitored parameters included
temperature, DO, turbidity, suspended solid, pH, ammonia, fecal coli form, BOD,
COD, phosphate, conductivity and heavy metals. The average WQI was found to be
very low at a meager 41 % and quality of the water declined further during dry
season. Schultz ( 2001 ) critiqued the index watershed indicator on the basis of these
tests as well as some other considerations, and suggested that if the index were to be
explicitly based on multi-attributed utility theory and methods, some of the diffi-
-
culties could be considerably resolved.
Khan et al. ( 2003 ) studied the water quality of the three selected catchment areas
of the Atlantic region: Mersey River, the Point Wolfe River and the Dunk River,
using the Canadian Water Quality Index and British Columbia Water Quality
Index. They also applied linear and quadratic models to analyze the water quality
trends. The results demonstrated that the water quality trend for raw water (before
treatment) used for drinking has improved considerably on the Point Wolf River.
Said et al. ( 2004 ) described the limitations of the application of a few water
quality indices such as NSWQI, British Columbia Water Quality Index (BCWQI),
Oregon WQI, Florida WQI and Watershed Enhancement Program WQI, and then
they developed a new WQI which proceeds in two steps. The
rst step ranks the
water quality parameters according to their signi
cance. These parameters include
DO, total phosphate, fecal coli form, turbidity, and speci
c conductivity. They give
higher rank for DO than fecal coli form and total phosphate. Turbidity and specific
conductivity, on the other hand, are given less in
uence. Jafarnejad ( 2005 ) studied
water quality index of Kaurn River and using NSWQI. Debles et al. ( 2005 )
employed water quality index from nine physicochemical parameters, periodically
measured through January 2000 to November 2000 at sampling stations on the
Chillan River in central Chile. Their results showed that the river boasted good water
quality in the upper and middle parts of the catchment area, but downstream,
especially during dry season, the quality deteriorated. This was due to the discharge
of urban wastewater into the river. They also applied principal component to modify
existing water quality. The study indicated that the application of modi
ed WQI
reduces the cost associated with its implementation. Taebi et al. ( 2005 ) applied three
eutrophication indices to de
ne water quality in north east of Persian Gulf.
Bordalo et al. ( 2006 ) applied a modi
parameter Scottish WQI to assess
the monthly water quality of the Doura River, an internationally shared River basin,
during a 10 year period (1992
ed nine
-
2001). The 98,000 km 2 of the Dorian River split
between upstream Spain (80 %) and Portugal downstream (20 %). The water
received by Portugal from Spain was of much reduced quality (WQI 47.3
-
±
0.7 %).
Quality; however, increased steadily downstream up to 61.7
0.7. In general, the
water quality in all of the monitoring stations was at best mediocre and often poor.
Lumb et al. ( 2006 ) applied Canadian Council of Ministers of the Environment
Water Quality Index (CCMEWQI) to determine the water quality of the ackenzie-
Great Bear Sub-basin. The results of their study showed that the water quality of the
basin is impacted by high turbidity and total trace metals (mostly particulate) due to
±
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