Salinity Intrusion and Seasonal Water Quality Variations in the Tidal ...

peak value is 200 mg/L only and at the western extremity, where it merges
with the Karankkodam thod, there is nominal tidal action and yet chloride
rises to 300 mg/L only and then shows a declining tendency. Hence, for all
practical purposes the canal is a fresh water source all through the year. For
most part of the year alkalinity dominates total hardness indicating that
hardness is temporary and that HC03 is the governing component.
3.2.2 Chithrapuzha-Kadambrayar river system is fresh water through out the
year down to Ambalamugal. At FACT, Irumpanam and Kaniyampuzha,
chloride levels pick up from the middle of October, and hit an annual peak
in the first half of March, when at Kaniyampuzha chloride level nears 9000
mg/L, whereas at Irumpanam and FACT it is around 2600 mg/L. From the
middle of March, chloride levels fall and reach nominal levels by the
middle of May. In the tidal stretch ofthe river, salinity makes a minor peak
in early October to the tune of 1500 mg/L at Kaniyampuzha presumably on
account ofthe inter-monsoonallull. The inference is that, above FACT, the
river water is fresh throughout the year. From FACT to Kaniyampuzha, it
is fresh from the second halfofMay to late September.
3.2.3. In the case of Edappally thod, the water course from Muttar puzha to
Marottichod is fresh throughout the year, with a nominal rise in chloride
from the beginning of December to the latter half of April. From Attipetty
nagar downwards, the water is saline from early November to early June.
But Attipetty Nagar does not ever become as saline as the points
downstream. At Attippetty, the maximum value of chloride is 2700 mg/L,
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