How LiDAR is Transforming Hydropower Projects in Nepal

Nepal has an immense hydropower potential of around 83,000 MW, with about 42,000 MW considered economically feasible (as per the government report). However, only a small portion of this potential has been developed so far. One of the major reasons is the challenging terrain of Nepal, which makes surveying and project planning difficult and time-consuming.

Traditionally, hydropower surveys relied on methods such as total stations, traversing, and levelling. While these techniques are accurate, they are slow and labour-intensive, especially in Nepal’s steep and rugged landscapes. As a result, survey work often delays project development. Today, modern technologies such as DGPS, drone photogrammetry, and LiDAR are transforming how surveys are conducted from preliminary site studies to construction monitoring.

Working in a specialised survey company, Geotech Engineering Space Pvt. Ltd., I have had the opportunity to observe both traditional and modern surveying approaches. Traditional methods still play an important role in providing precise ground measurements. However, modern technologies are significantly improving the speed, coverage, and efficiency of data collection. Working with advanced datasets helped me realise how these technologies simplify complex terrain mapping and support better project planning.

Figure 1: Laxmi Acharya at Geotech Engineering Space Pvt. Ltd. office

Aerial LiDAR for Large-Area Mapping

Aerial LiDAR, deployed via drones or aircraft, uses laser pulses to create high-resolution 3D maps of large areas quickly. It penetrates vegetation to capture bare-earth topography, generating precise contours and digital elevation models (DEMs) essential for hydropower site selection and feasibility studies. In Nepal's steep Himalayan regions, this cuts survey time from weeks to days, ideal for river basins and reservoir planning. Drone photogrammetry complements it by providing visual overlays, but LiDAR excels in accuracy for volume calculations and hydrological modeling.

Hybrid Approach: SLAM LiDAR for Difficult Areas

Some locations remain difficult to capture with aerial surveys. These include dense forests, narrow gorges, steep slopes, and core project areas. To fill these data gaps, survey teams use handheld SLAM (Simultaneous Localisation and Mapping) LiDAR systems. These portable scanners, often carried as backpacks or rover-mounted units, create real-time 3D models while the operator walks through the site.

For hydropower projects, SLAM LiDAR is especially useful for:

• Mapping areas under dense tree canopy

• Surveying tunnel routes and intake structures

• Capturing core project infrastructure

• Conducting route alignment surveys

This technology complements aerial LiDAR by providing centimetre-level detail in areas where aerial scanning cannot reach.

Figure 2: Both SLAM Lidar (Lixelkity K1) & Drone M400 with H600 GVI sensor mounted

LiDAR Across the Hydropower Project Lifecycle

At the company where I work, most survey projects are related to the hydropower sector across different regions of Nepal. LiDAR technologies are now used at multiple stages of project development.

• Preliminary/Feasibility: Aerial LiDAR maps vast catchments for runoff estimates and dam site viability.

• Detailed Design: Combine aerial data with SLAM for core areas (powerhouses, tunnels) and drone photos for visual context - no more eye-judgment errors.

• Construction Monitoring: SLAM LiDAR tracks progress, measures as-built vs design (e.g., tunnel excavation), and verifies durability. Already-established projects can retro-fit SLAM for ongoing monitoring without disrupting operations.

This hybrid approach works particularly well in Nepal’s steep and forested terrain, where aerial LiDAR provides large-scale coverage while SLAM captures detailed information in obstructed areas.

Key Benefits for Nepal's Hydropower

LiDAR accelerates Nepal's hydropower push by slashing survey costs 50-70%, improving accuracy to minimise redesigns, and enabling private investment via reliable data. It supports government policies prioritising rapid development, reducing import dependence and boosting economic growth. Real-time monitoring ensures project durability from inception to operation.

Limitations and Challenges

Despite its benefits, LiDAR also presents some challenges. Processing LiDAR data requires high-performance computers and large storage capacity, which can be difficult to manage in remote project locations. The initial cost of LiDAR equipment and surveys is also relatively high. Additionally, dense vegetation may sometimes scatter laser signals, which is why SLAM LiDAR surveys are often needed to complement aerial data.

Another important factor is the need for skilled professionals who can process and analyse LiDAR datasets effectively. Fortunately, training opportunities in these technologies are gradually increasing.

So, LiDAR is not just a new surveying tool; it is becoming a key technology for accelerating hydropower development in Nepal. By enabling faster data collection, more accurate terrain modelling, and improved construction monitoring, LiDAR is helping engineers overcome the challenges of Nepal’s complex landscape.

Learn more by visiting: https://geotechspace.com.np/

Figure 3: Photographs of our office team presenting the importance of LiDAR technology to government stakeholders

About the Author

Laxmi Acharya is a geomatics engineer from Nepal with a strong interest in advancing modern surveying practices through the use of LiDAR technology and aerial mapping.