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

sweep the earth following the sun and the moon. When they move into shallow
waters, landmasses, channels etc., height variation takes place. The differences in
internal viscosity affect the propagation of tides. The velocity of the wave is
dependent on depth of the water column. Presence of landmasses arrests the progress
of tides and the topography of the ocean floor and the estuarine geometry modify
them. In confined bodies of water resonance effects between the free period of
oscillation of traveling tidal wave and the confining basin may cause tilting and
cresting.
The tide at Cochin is usually semi diurnal with considerable differences
between the two high waters or the low waters; on some days the tide may be purely
diurnal. The maximum tidal range is about 1m. There is considerable monthly
variation in the water levels; however the annual pattern is more or less stable. The
highest high water reaches its maximum in the dry season (Kuttanad Water Balance
study, Vo12, 1988).
Cochin is interspersed with tidal canals generally with an east-west strike,
except for TP canal and Karankkodam thod. In all these canals, water budget is
modified by tidal influence whose magnitude is decided by channel geometry and
distance from the estuary and nutrient levels are decided by urban runoff and sewage
input.
Figures 3.199 to 3.206 show the tidal characteristics (amplitude and flow
rates) of Chithrapuzha and Chittoorpuzha and the corresponding chloride variations.
On 19 th of December, tide levels were monitored simultaneously at two sites nearly 5
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