How We Conduct River Surveys Using Drone, DGPS, and Indigenous Sonar System with Boat
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Image: A high-resolution aerial view of the river corridor captured during our drone survey, providing detailed imagery for precise mapping and analysis of riverbanks and adjacent floodplains.
Accurate river surveys are essential for water resource management, irrigation planning, flood control, navigation projects, and infrastructure development. At Agniforge, we combine advanced drone photogrammetry, precision DGPS control, and our in-house developed sonar-equipped survey boat to deliver reliable, high-resolution riverbed and riverbank data. Below is our detailed methodology.
1. Aerial Survey with Drone Photogrammetry
Our survey begins with high-resolution drone flights along the river corridor. Our drones are equipped with calibrated photogrammetry cameras capable of achieving ground sampling distances (GSD) of 2–5 cm/pixel, ensuring precise elevation models.
Flight planning ensures 80% forward and 70% side overlap, enabling accurate 3D point clouds. The drone captures the riverbanks, surrounding terrain, and visible parts of the river, providing:
Orthomosaic maps of the river and adjacent areas
Digital Elevation Models (DEMs) of floodplains and embankments
Up-to-date imagery for monitoring erosion, encroachment, or vegetation changes
2. DGPS Ground Control Points (GCPs) and Validation
To achieve survey-grade accuracy, we establish a network of DGPS ground control points along the river stretch. These GCPs ensure that drone-derived data is accurately georeferenced and meets the required vertical and horizontal tolerances.
During processing, we validate the drone-derived DEM against DGPS points to calculate and correct any residual errors, guaranteeing reliable elevation models.
3. Riverbed Profiling with Indigenous Sonar System
For sections of the river covered by water, photogrammetry cannot capture the riverbed. To overcome this, we deploy our in-house designed, stable survey boat fitted with a single-beam sonar system integrated with RTK-GPS. This system enables synchronized depth and position recording with centimeter-level accuracy.
Our sonar system profiles the riverbed by:
Capturing continuous depth measurements along planned transects
Recording precise coordinates of each depth point using RTK-GPS
Creating accurate longitudinal and cross-sectional profiles of the underwater channel
The indigenous design of our boat ensures excellent stability and maneuverability even in narrow or shallow stretches, reducing data noise and improving measurement reliability.
4. Data Integration and Processing
We process drone, DGPS, and sonar data on our proprietary processing platform. By merging the riverbank DEM with sonar-derived bed points, we generate comprehensive 3D models and cross sections of the entire river channel.
From this integrated dataset, we produce:
Cross sections at specified intervals (e.g., every 25 meters)
Longitudinal profiles of river thalweg (deepest path)
Detailed cut and fill calculations for dredging or design
Volumetric analysis for sedimentation and capacity assessment
5. Reporting and Deliverables
Our final deliverables typically include:
Orthomosaic maps and high-resolution imagery
DEMs of riverbanks and floodplains
Accurate cross sections and longitudinal profiles
Cut/fill volume reports
DGPS control reports with accuracy validation
CAD, GIS, and PDF outputs as per client specifications
Why Choose Agniforge for River Surveys?
With our combination of aerial, ground, and bathymetric survey technologies, we provide a one-stop solution for comprehensive river assessments. Our indigenous sonar system reduces dependency on expensive external equipment, allowing us to offer competitive pricing without compromising on accuracy or quality.
By choosing Agniforge, clients gain a technology-driven, cost-effective, and reliable partner for all river survey requirements.
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1. Aerial Survey with Drone Photogrammetry
Our survey begins with high-resolution drone flights along the river corridor. Our drones are equipped with calibrated photogrammetry cameras capable of achieving ground sampling distances (GSD) of 2–5 cm/pixel, ensuring precise elevation models.
Flight planning ensures 80% forward and 70% side overlap, enabling accurate 3D point clouds. The drone captures the riverbanks, surrounding terrain, and visible parts of the river, providing:
Orthomosaic maps of the river and adjacent areas
Digital Elevation Models (DEMs) of floodplains and embankments
Up-to-date imagery for monitoring erosion, encroachment, or vegetation changes
2. DGPS Ground Control Points (GCPs) and Validation
To achieve survey-grade accuracy, we establish a network of DGPS ground control points along the river stretch. These GCPs ensure that drone-derived data is accurately georeferenced and meets the required vertical and horizontal tolerances.
During processing, we validate the drone-derived DEM against DGPS points to calculate and correct any residual errors, guaranteeing reliable elevation models.
3. Riverbed Profiling with Indigenous Sonar System
For sections of the river covered by water, photogrammetry cannot capture the riverbed. To overcome this, we deploy our in-house designed, stable survey boat fitted with a single-beam sonar system integrated with RTK-GPS. This system enables synchronized depth and position recording with centimeter-level accuracy.
Our sonar system profiles the riverbed by:
Capturing continuous depth measurements along planned transects
Recording precise coordinates of each depth point using RTK-GPS
Creating accurate longitudinal and cross-sectional profiles of the underwater channel
The indigenous design of our boat ensures excellent stability and maneuverability even in narrow or shallow stretches, reducing data noise and improving measurement reliability.
4. Data Integration and Processing
We process drone, DGPS, and sonar data on our proprietary processing platform. By merging the riverbank DEM with sonar-derived bed points, we generate comprehensive 3D models and cross sections of the entire river channel.
From this integrated dataset, we produce:
Cross sections at specified intervals (e.g., every 25 meters)
Longitudinal profiles of river thalweg (deepest path)
Detailed cut and fill calculations for dredging or design
Volumetric analysis for sedimentation and capacity assessment
5. Reporting and Deliverables
Our final deliverables typically include:
Orthomosaic maps and high-resolution imagery
DEMs of riverbanks and floodplains
Accurate cross sections and longitudinal profiles
Cut/fill volume reports
DGPS control reports with accuracy validation
CAD, GIS, and PDF outputs as per client specifications
Why Choose Agniforge for River Surveys?
With our combination of aerial, ground, and bathymetric survey technologies, we provide a one-stop solution for comprehensive river assessments. Our indigenous sonar system reduces dependency on expensive external equipment, allowing us to offer competitive pricing without compromising on accuracy or quality.
By choosing Agniforge, clients gain a technology-driven, cost-effective, and reliable partner for all river survey requirements.
