Study Area Overview:

The project area covered 190 km across the regions of Province 1, 2, and 3 in Nepal, which include a diverse range of terrains, from flat plains to rugged mountainous areas. These regions are critical for infrastructure development, especially in terms of electricity transmission, as they provide a link between remote power generation sites and the national grid.

– Province 1: This region includes the hilly and mountainous zones, with elevations that range from the plains of the Terai to the high Himalayan ranges. The project area particularly covers the Arun Valley, a significant hydropower hub.

– Province 2: Known for its flat terrain, this area mainly consists of the Terai plains, making it suitable for large infrastructure projects. The survey here focused on ensuring the alignment of the transmission line while minimizing its impact on the densely populated regions.

– Province 3: This province includes Kathmandu Valley and other hilly areas. Surveying in this region posed challenges due to urban density and rugged terrain, which required precise and high-resolution mapping to ensure the proper alignment of the transmission line.

 Key Components of the Survey:

1. Airborne and Drone-Based LiDAR Acquisition:

   The project involved both helicopter and drone-based LiDAR surveys, allowing the team to cover large swaths of difficult-to-access terrain and urban areas. The use of drones was particularly effective in urban and semi-urban areas where helicopter flights were less feasible. This dual approach provided flexibility and efficiency, capturing high-resolution data in areas with varying geographical features.

2. Benchmarking and Control Point Establishment:

   Setting up control points and benchmarks throughout the 190 km stretch was a key aspect of the survey. These points were established using Differential Global Positioning Systems (DGPS) and Total Stations (TS) to ensure that all collected data was georeferenced and could be integrated into existing maps and plans.

3. LiDAR Data Processing:

   Once the data was captured, it underwent extensive processing. The raw LiDAR point clouds were classified into ground, vegetation, and structures. This classification was crucial for generating the key deliverables such as Digital Terrain Models (DTM) and Digital Surface Models (DSM), which would be used in the design and construction phases of the transmission line project.

 Deliverables:

– Ortho Photos: High-resolution orthophotos were generated, providing a visual reference for the project. These images were critical for planning and alignment verification.

– Contour Maps: The contour maps offered a detailed representation of the terrain’s elevation, which helped in identifying optimal transmission line routes that minimized the need for costly terrain modifications.

– Digital Surface Models (DSM): The DSM provided a 3D model of all the surface features, including trees, buildings, and other structures, which helped in planning the transmission towers and ensuring that the lines would not interfere with existing infrastructure.

– Digital Terrain Models (DTM): The DTM showed the bare-earth surface, with all vegetation and structures removed. This model was essential for understanding the underlying terrain and helped in planning the foundation structures for the transmission line towers.

– Topographical Maps: Comprehensive topographical maps combining DSM, DTM, and ortho photos were generated to provide a complete view of the project area. These maps were essential tools for engineers and planners, ensuring that all aspects of the project were accurately represented in both 2D and 3D formats.

This project, carried out for the Nepal Electricity Authority, played a crucial role in laying the foundation for the development of Nepal’s electric transmission infrastructure, ensuring that the new transmission line could be constructed with precision while minimizing environmental and social impacts.