Presenter : S Narendra Prasad
Tawang river basin located between 27° 25’ and 27° 45’ N latitude, and 91° 42’ and 92° 39’ E longitude, covering an area of 2,172 sq. km. is estimated to have hydel power potential of 2057 MW constituting 3.6% of the calculated total hydel potential of 57027 MW of entire Arunachal Pradesh. With an estimated 56 percent of the geographical area under forest cover, and a low population density of 13 per sq. km, it has attracted hydel project investments. In order to harmonize the environmental conservation and hydel project development, a Cumulative Environmental Impact Assessment (CEIA) was taken up. The CEIA had multiple thematic assessments such as geology, hydrology, vegetation, plant and wild life assessments, socio-economic profiles, cultural diversity and invasion potential of invasive species. This necessitated development of intensive geospatial assessments in a desktop environment. The objective of this paper is to describe our experience of harnessing QGIS, an open-source GIS software, to help solve key issues during the CEIA process. QGIS, was deployed for deriving comprehensive development scenarios. The methods consisted of using off the shelf available geospatial data as well as primary field data. Extensive use of freely available Landsat 8 data along with vector data in public domain resulted in deriving slope, aspect, and elevation information. This was integrated with the biological data on birds, mammals and vegetation to understand potential impacts of hydel projects at various elevational zones. The QGIS analyses thus aided effective decision making in assessing the impacts. The key results indicated the impact zones from the river corridors, estimates of loss of forest cover and impact on habitats of endangered primate, the Arunachal macaque, and many other threatened plant and animal species. Our experience from Tawang river basin study confirms that very effective outreach programme can be developed deploying open source web GIS tools.
Key words: Hydel power projects, Cumulative Environmental Impact Assessment, QGIS, River