12. Using Satellites and GIS for Surveying Proposed Hydro Sites

The National Hydroelectric Power Corporation (NHPC) of India is using satellite remote sensing techniques and Geographic Information System (GIS) technology for performing studies of natural resources in areas proposed for hydroelectric development. Using these techniques for surveying is quicker and more cost-effective than conventional approaches to surveying. Historically, watershed management plans have been prepared based on actual ground surveys, interaction with local people, and analyses of topographic maps. From these sources, project developers collected information such as land use patterns, type of vegetation cover, geomorphological features, elevation differences throughout the catchment, direction of land slope (which defines how the ecology is affected), soil type, and erosion potential. However, when the area proposed for hydro development was not easily accessible, the use of these conventional means proved to be difficult. In addition, when the surveying was conducted over many years, it was difficult to depict recent changes in the catchment owing to the fact that toposheets from the Survey of India, a national survey and mapping organization under the India Department of Science and Technology, are not revised every year. The difficulties with these traditional methods can be overcome through the use of remote sensing techniques.