Diversion structure survey

Diversion structures are used in Hydro Electric and Irrigation projects. In general, the terrain around these projects is very difficult to survey with conventional methods as the terrain is mostly inaccessible or not safe for the surveyors. We have used terrestrial laser remote surveying methods along with total station to map the area. This expedites the surveying work and provides a comprehensive data about site. Conventional surveys mostly rely on a few profiles and few points for generating contours. However, in case of terrestrial laser scanning the terrain is covered with a large number of points each measured with high precision, thus representing the terrain better. This further raises confidence on the design, reservoir volume and area estimation, slope measurement and zoning the landslide prone areas. This project was conducted for Uttranchal government in the Kumaoun hills. The figure shows an image of the terrain showing the high slopes which are difficult for a person to climb with a prism target or GPS antenna. The figure also shows a point cloud generated for this using TLS. Elimination of trees and bushes from the point cloud provides several points on the land surface which are employed to generate the contours. A contour interval of 50 cm or better can be achieved for less vegetated terrains, while 1m contour interval is possible for terrain with medium vegetation cover.