In order to better detect the scouring and deposition of Longyangxia Reservoir and verify the performance of the domestic multibeam sounding system in large reservoirs, in September 2017, a water conservancy and hydropower design company in Northwest China invited Hydro-Tech by using MS400 of carrying out precise measurement of the evolution of underwater scour in key areas of Longyangxia Reservoir, thus an accurate underwater three-dimensional terrain data was obtained.
1. Survey Implementation
The equipment used in this survey is the Hydro-Tech MS400 multi-beam echosounding system. According to the characteristics of the survey ship, the system adopts a triangular bracket structure which fixing by wire rope, the installation is simple and convenient. MS400's portability and installation-free calibration features have played a critical role.
The following picture shows the installation picture of the mounting bracket:
2. Project Accomplishment
2.1 Overall terrain pseudo-color map
With basic post-processing, the topographic pseudo-color rendering of the Longyangxia Reservoir survey area was obtained:
Pseudo-color map of the overall survey area
2.2 3D point cloud figure
The underwater terrain also can be viewed in the form of a 3D point cloud display. The following figure shows a partial 3D point cloud map of the survey area:
Point cloud map of underwater scoured area
Point cloud map of underwater scour
2.3 3D DTM model
Through the multi-beam post-processing software, you can directly obtain the 3D surface model of the underwater terrain, and use the 3D display mode function to view the underwater terrain and landforms we care about.
Underwater channels and landforms
The traces left by the water line scouring
Scouring and deposition of underwater shore foundation
Non-primitive channel underwater scour landforms
The Longyangxia Reservoir was measured with MS400 multi-beam, and the data density and measurement accuracy far exceeded the expectations of the cooperative units.
(1) Comparing the key positions with the single-beam sounder, the sounding accuracy fully meets the measurement requirements, and the measurement efficiency is greatly improved;
(2) Compared with imported first-line brand multi-beam bathymetry systems, the accuracy and coverage efficiency of underwater terrain measurement are consistent, and the terrain details of all key locations can be clearly reflected;
(3) Hydrao MS400's integrated design and full Chinese software make the operation of the equipment very simple, and the complexity of the field is almost equivalent to that of a single beam, which is very suitable for the requirements of mobile surveys such as rivers and reservoirs.
The performance and characteristics of the Hydrao MS400 multi-beam bathymetry system and the measurement results of the Longyangxia Reservoir have been unanimously approved by the experts and leaders of the cooperative units.