Impact of Anthropogenic Interventions on the Vembanad Lake System

Estuarine and coastal zone processes have always been topic of research due to their being prime centers of rich resources like diverse habitat and natural beauty. Other than ecological reasons these aquatic bodies act as important economic centers, tourist places, serve in navigational purposes, and fishing. One of the India’s most valued natural sites is the Vembanad Lake and estuarine system that lies on the western coast in the state of Kerala. This natural system, which comprises the lake, the Kuttanad wetland region and the Cochin estuary, is included in the Ramsar list of important wetland sites. Six major rivers, namely, Periyar, Muvattupuzha, Pamba, Manimala, Meenachil, and Achenkovil contribute to the system. The whole system has been vastly modified throughout the last couple of centuries owing to sedimentation and human-driven factors. On the other hand, there has been constant reclamation of the low-lying areas on the periphery of the lake and the wetlands, leading to reduction in the spread area. The special characteristics of these lands that lie to the east of the lake is that the ground level is lower than the lake water level. Therefore, the lake water easily serves for irrigational purpose in these adjacent lands. According to tentative proposals in the recent years it was intended to make further developments in the catchment areas for various purposes. The present paper takes a modeling approach to find out what would be the possible impact on the lake water profile as well as salinity/solute concentration if these proposals are implemented. The study has been carried out using the two-dimensional hydrodynamic modeling software MIKE 21 with HD and AD modules. The results from the hydrodynamic model of the lake, although not fully representative, show that the lake water levels and salinity might face quantitatively relevant changes which can pose a threat to the natural environment.

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