Water Quality Indices (WQI) - Water Quality Management: Assessment and Interpretation - page 31

Table 3.4 The results of
opinion for K ā r ū n River
Water Quality data
(Asadolahfardi et al. 2005)

Water quality
parameters

Mean of all
signi cance

Temporary
weights

Final
weight

DO 1.89 0.83 0.13

BOD 5 1.56 1.00 0.15

pH 2.33 0.67 0.11

NO 3 2.11 0.74 0.11

PO 4 2.72 0.57 0.09

TS 2.33 0.67 0.1

Temperature 3.44 0.45 0.07

Turbidity 2.40 0.65 0.1

Fecal coli form 1.67 0.93 0.14

Table 3.5 Comparison of
NSFWQI weighting factors
and weighting factor in this
case study

Water quality
parameters

NSFWQI weight-
ing factors

Weighting factor in
this study

DO 0.17 0.13

BOD 5 0.15 0.11

pH 0.10 0.11

NO 3 0.11 0.10

PO 4 0.09 0.10

TS 0.10 0.07

Temperature 0.07 0.10

Fecal coli form 0.14 0.15

show that the two final weightings are about the same, and the maximum differences

belong to BOD and temperature (Table 3.5 ). Therefore, the use of the questionnaire
responses may be acceptable to apply to the study. Finally, water quality was com-
puted according to mentioned methodology. Table 3.6 presents the results.
One of the advantages of the NSFWQI is its simplicity and availability of water
quality parameters in the most water quality monitoring programs, and again, as
previously mentioned, while the subjectivity of the method ' is is a disadvantage, it

caused minimum effects in the final result. Another notable disadvantage is the

method inability to indicate water quality trends, but that was not among the
objectives of this case study. The aim of this case study was to clarify the existing
situation of water quality and show the application of the methodology.
As described in Table 3.6 ,K

in River water quality from Shahhid Abahpoor to
Shoshtar city was average, but as water circulated through the city, in Gargar
branch, water quality worsened due to the discharge of raw domestic wastewater to
the river. Dez River from Dez dam to Band Gheer and from Band Gheer to Ramin
water station also possesses medium water quality. The water quality of the Dez
River in Ahvaz city of Zargan monitoring station is not satisfactory, since industrial
and domestic wastewater discharges to the river at that point. The quality of the
water moving toward the Darkhovain monitoring station was middling as well.

ā r ū