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

onset of urbanization. Even today, a shadow of these regions' former self is discernible.
Such a pattern had avoided flooding problems effectively as natural run offhad a place to
go. The situation was further confounded when railroads were laid giving rise to artificial
ridgelines dividing natural water sheds. Numerous culverts en route choked or
bottlenecked all the existing canals, partly impeding inland navigation and reducing flood
discharging capacity.
2.5 List ofimportant tidal canals of Greater Cochin
The environmentally significant tidal canals (called "Ihodu or Thod' In the local
parlance) are listed below and further illustrated in Figure 2.6
1. Thevara - Perandoor canal:( Figure 2.7) It connects Perandoor on the north with
Thevara on the south. It was once used for navigation, fishing, irrigation, recreation,
flood alleviation and goods transportation. Kottayam-Ernakulam railway line has
divided this canal into two. The water is by far putrid and stagnant. Near anoxic
condition prevails in many parts. Certain segments in the Perandoor portion have
silted up impeding natural flow. It is the repository of domestic and municipal
waste. It is no more navigable and no fish survives. Effective dredging could revive
the flood alleviation potentials. This canal has significant urban relevance in the
present settings. It divides the city into two halves and is the chief repository of
urban liquid and solid discharges. Rejuvenation and committed maintenance of this
canal could give a tremendous fillip to the aesthetic appeal ofthe urban environment.
Ifthesouthern and northern segments ofthe canals are linked across the railroad and
if the obstacles at Aryampadom are removed water would oscillate between the
southern and northern extremities, being propelled by the gradient induced by tidal
41