Precision Bathymetry in Vertical Canyons with HydroBeam M4

プロジェクトの背景

A narrow river winds through a dramatic canyon, its steep, near-vertical rock walls rising sharply on either side. Water depths fluctuate unpredictably—from shallow 1-meter patches to deep 20-meter pools—creating a challenging and dynamic underwater landscape. For the local hydropower plant, having an accurate understanding of this terrain isn’t just a technical task—it is critical for operational safety. Traditional surveying tools struggle to obtain reliable measurements along such near-vertical canyon walls, leaving gaps in the data and increasing risk.

Figure 1: Hydropower Plant

To overcome these challenges, the project team deployed the HydroBeam M4 multibeam echosounder, designed specifically for high-precision hydrographic surveys in complex and vertical underwater terrains.

Challenges Beneath the Surface

Surveying a canyon like this presents multiple obstacles:

• • • Tight confines: some river sections measure less than 20 meters wide.
    • Vertical walls: extreme slopes create beam distortion and unpredictable acoustic reflections.
    • Variable depths: rapid transitions between shallow and deep water make consistent measurement difficult.
    • Acoustic anomalies: multiple reflections between canyon walls, riverbed, and water surface can produce noisy or misleading data.

Figure 2: Vertical Rock Walls on Both Sides of the River Channel

Deploying the Solution 

Figure 3: HydroBeam M4 Multibeam Echosounder

The project team relied on the HydroBeam M4’s advanced capabilities to tackle these challenges head-on:

• • • 150° swath coverage for extended side-wall data acquisition
    • 1024 beams providing dense, high-resolution bathymetric point clouds
    • Vertical Terrain Algorithm ensures stable measurements on steep slopes and vertical walls.
    • Integrated GNSS, IMU, and SVS simplify installation and allow precise positioning and motion compensation

Data Acquisition Workflow

1.Survey Line Planning

• Parallel survey lines with ≥30% overlap to ensure full coverage
• Calibration measurements gathered at key terrain spots

2.Field Survey

• Small manned survey vessel equipped with HydroBeam M4
• Sound velocity profiles measured in multiple locations to correct for sound propagation variations

Figure 4: HydroBeam M4 Installed on Small Manned Survey Vessel

3.Real-Time Acquisition

• HydroBeam Monitor software automatically adjusts system parameters to ensure stable data.
• SLHydro Survey software collects the data and provides real-time visualization.

Figure 5: Real-Time Data Visualization

Data Processing

Software: SLHydro Survey used for post-processing

• • • Data Integration: GNSS, IMU, and multibeam measurements merged with calibration parameters
    • Noise Filtering: Removal of anomalous or erroneous depth points
    • Output: High-resolution 3D underwater point clouds, contour maps, and cross-sectional profiles suitable for engineering analysis

Figure 6: Post-Processing of Survey Data

成果物

Figure 7:3D Underwater Point Cloud Visualization

Figure 8: Bathymetric Contour Map

The canyon survey proves that HydroBeam M4 is a game-changing solution for challenging vertical terrains. Delivering full-coverage, high-resolution bathymetry with reliability and precision, it empowers engineers and operators to make confident decisions while setting a new standard in hydrographic surveying.

Figure 9: River Cross-Section Profile

Project Outcome
The HydroBeam M4 multibeam echosounder successfully transformed a complex vertical canyon survey into a precise, efficient, and reliable operation. Beyond delivering high-resolution, full-coverage bathymetry, it empowers engineers and hydropower operators to make informed decisions with confidence, redefining standards for hydrographic surveying in challenging environments.