Study Area:

The “Airborne LiDAR Survey for Preparation of Topographic Map for Bagmati Irrigation Project” covered a substantial area of 900 square kilometers across four districts in Nepal: Bara, Rautahat, Sarhali, and Mahottari. This region encompasses diverse landscapes that include agricultural lands, river systems, and varying topographies. The area is significant for the Bagmati Irrigation Project, aimed at enhancing irrigation and water management in the region.

The project area spans across both lowland and riverine environments, requiring a detailed and accurate topographic survey to support the development and implementation of irrigation infrastructure. The combination of flat and undulating terrain posed unique challenges that necessitated the use of advanced LiDAR technology to capture comprehensive and precise elevation data.

 Project Objectives:

– Establishment of Control Points: Utilize GNSS (DGPS) and digital level equipment to establish control points in a 3 by 3 km grid across the project area. This process was crucial for ensuring accurate data alignment and integration.

– Conduct Airborne LiDAR Survey: Employ helicopter-based LiDAR technology to capture detailed elevation data across the entire project area. The objective was to generate high-resolution topographic information to support the design and planning of the irrigation infrastructure.

– Preparation of Topographic Map: Produce a topographic map with a contour interval of 0.25 meters, providing a precise representation of the terrain. This high-resolution map was essential for effective irrigation planning and management.

 Deliverables:

– Ortho Photos: High-resolution orthophotos were generated to provide an accurate, geo-referenced view of the surveyed area. These images offer a detailed visual representation of the landscape, aiding in planning and analysis.

– Contour Maps: Detailed contour maps were prepared with a contour interval of 0.25 meters, illustrating the elevation changes across the project area. These maps are critical for understanding terrain variations and planning irrigation infrastructure.

– Digital Surface Models (DSM): DSMs were created to represent the earth’s surface, including all natural and man-made features. This model provides a comprehensive view of the surface features within the project area.

– Digital Terrain Models (DTM): DTMs were developed to depict the bare ground surface, excluding vegetation and structures. This model is essential for understanding the true landform and planning earthworks for irrigation projects.

– Topographical Maps: Comprehensive topographical maps were generated to offer a detailed overview of the terrain, including elevation contours and surface features. These maps are crucial for the design and implementation of irrigation systems and related infrastructure.

The airborne LiDAR survey for the Bagmati Irrigation Project provided high-resolution and accurate topographic data necessary for effective irrigation planning and management. The deliverables support various aspects of the project, ensuring that the irrigation infrastructure aligns with the existing topography and meets the project’s objectives.