Introducing of Ce-Qual-W2 Model and Its Application - Water Quality Management: Assessment and Interpretation - page 107

Fig. 6.12 The comparison between the amount of the TDS in the inlet and outlet of the Karkheh
reservoir from 2003 to 2004 (Badrghasemi 2002 )
6.4.1.1 Comment
As a whole, CE-QUAL-W2 model is a suitable tool for water quality prediction on
in reservoir. The results of the simulation in this case study showed that the existing
water has a good quality inside the whole of the reservoir and in 2003; there was no
accumulation of TDS at any points in the Dam. It is necessary to propose different
theories to estimate the quality of possible brininess of Karkhe reservoir.
In the simulation, it was assumed that with the increase of the discharge of 2004
relating 2003, the inlet water to the reservoir increased, and the amount of TDS in
2004 was equal to TDS in 2003. With this assumption, the simulation results indicated
that TDS in the reservoir in March 2004 was 17 mg/l more than in March 2003.
Considering these results if the circumstances do not change during the next few
years, the TDS in Karkhe reservoir may increase by 17 mg/l each year. Taking the
projected increase of TDS into account it is therefore possible to identify the timepoint
at which TDS pollution of the reservoir water will render it unsuitable for irrigation.
Considering the EPA standard, and also above preconception, it will take
24 years for the amount of TDS in the Karkhe reservoir to reach 1,000 mg/l from a
starting point of 600 mg/l in 2003. In other words, the Karkheh may not be suitable
for agricultural use in 24 years.
The mentioned theory depends on gaining the accurate information about
changing of TDS in Karkhe reservoir. If, as we project, the amounts of TDS
increase each year, the assumption will be reasonable.
As presented in Fig. 6.12 when inlet water has a high amount of TDS, the outlet
water has TDS. Hence, the water in the reservoir will gradually become salty.