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Influence of Forest Cover Change on Watershed Functions in the Western Ghats: A Coarse-Scale Analysis

CISED Research Team: Sharachchandra Lélé, Jayasree V., Santosh Hegde

Complementing the field study of the relationship between land-cover and watershed services, we have attempted a unique approach to examining this relationship in the densely forested and high rainfall region of the Western Ghats of peninsular India at a wider scale. This approach involves a statistical analysis of cross-sectional and time-series data for a sample of catchments in this region for which streamflow data are being collected by state agencies for several years. With streamflow data from Karnataka’s Water Resources Development Organisation, rainfall data from the Directorate of Economics & Statistics, land-cover data from the interpretation of satellite imagery and ancillary data from various other sources, we put together a dataset for 20 catchments within the Karnataka region of the Western Ghats.

In our detailed time-series analysis of the rainfall-runoff relationship in four west-flowing river basins in southern Karnataka and Kerala - Polali (Gurupur river), Dasanakatte (Varahi river), Yennehole river, and Achankovil (Achenkovil river) - we found that:

•    There has been limited land cover change in these  catchments
•    There has been a perceptible change in the runoff pattern only in two of the four catchments, viz, Polali and               Dasanakatte, with both showing a declining runoff: rainfall ratio (see Figure 5)
•     In both these catchments, the land-cover change alone is not enough to explain this declining ratio

Further, field investigations in the Polali catchment indicate that the major cause of declining runoff may be increased official diversion and illegal pumping from the riverbed.

 

Contact: cised@isec.ac.in



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