What is hydrographic surveying?
The term "hydrographic survey" refers to engineering and surveying, Surveying work related to mapping the bottom of the various types of natural and artificial water
Drives with stormwater and industrial wastewater.
Why would you want to shoot the bottom of bodies of water?
The construction of topographic maps of the bottom of water bodies interested customers the company "Engineering Guild" in various cases:
- in the improvement of water bodies, should be clarified when the need for their removal of accumulated sediment, trash outside and dense debris;
- if necessary, assess the necessary volume of bottom cleaning and dredging;
- if scheduled maintenance of construction within the water area and on the territory of its coastal zone;
- to clarify the situation in the wake of the navigable water body;
- with hydrological and environmental studies.
The hydrographic survey covering shores
Quite often, in the planning of hydrographic surveys there is a need in the scope of engineering and survey work, not only the bottom of the water body, but also its coastal zone. For example, when the shooting channel (the so-called shooting the bottom surface and the banks of the river on the segment). In these cases, the value of capturing the coastal territory or customer surveys indicated in the preparation of technical specifications for the production of engineering and geodetic surveying, or taken in accordance with existing regulations governing the conduct of channel surveys, taking into account the position of the water's edge in the low-water season.
The scope and accuracy of hydrographic survey
Performed hydrographic surveys the bottom of bodies of water, and hydrographic charts are built into engineering purposes, using standard scales ranging from 1: 500 (for small water bodies) to 1: 10,000 (for large reservoirs, lakes, large areas offshore). Based on this kind of shooting measurements points water bottom depth, the error which depends on the complexity of the equipment used and the recording conditions. Acceptable for most engineering problems considered depth accuracy:
- ± 10 cm (at a depth of less than 10 m);
- ± 20 cm (10-20 m);
- ± 50 cm (below 20 m).
Methods for geodetic measurements used when shooting the bottom of reservoirs
In practice, hydrographic surveys developed and successfully used fundamentally different methods of surveying measurements:
- mechanical (using lots, measuring rods);
- sonar (areal sonar and echo sounders depth point measurements with integrated GPS-receivers to facilitate binding);
- optical (photographing bottom with aircrafts, laser scanning).
Most often they are used individually, but for particularly important and is one hundred percent reliable information, conducted survey complex, combining the research program with two or more methods.
Moving the equipment for shooting on the job site
In contrast to conventional surveying, surveying equipment to transport on the job site with the hydrographic survey is required to use special tools. Depending on the area of the object and removes water approved recording program for these purposes may be used:
- unmanned aerial vehicles;
- small vessels and boats:
- inflatable and conventional boats.
Method local depth soundings
The most frequently used and spent in Ukraine hydrographic survey method is the method of local measurements. It is based on carrying out a series of point measurements of the depth profiles specify the number and orientation of which is dictated by the shape and size of the water body. depth measurements are made on the surface of the water, and the horizontal coordinates of the measuring point is tied to the nearest point of local geodetic networks. Detail, the precision of this method is determined by the number of profiles and set them along Surveying points. Accordingly, the price is calculated and hydrographic surveys.
Method areal sonar
hydrographic survey method using sonar provides information about the depth of the bottom is not only at the position of the measuring device, but at a certain distance from it. Deciphering sonar data - enough time-consuming procedure geodesic, and therefore the use of sonar method is justified only in large bodies of water, or if the target enters the detection of hydrographic survey at the bottom of the pond foreign objects of a relatively small size.
The hydrographic survey air
Progress in the development of unmanned aerial vehicles allowed to develop a method of hydrographic aerial deservedly becoming increasingly popular. In reservoirs with small depths (up to fifteen meters) and clean, quiet water hydrographic survey using drones not less effective than other methods of shooting, and the performance is even ahead of them. Aerial view allows you to quickly perform the field work stage at the bottom of a large area of the test. convenient and that aerial photography allows you to build and topographic plan of the coastal strip.
Results hydrographic survey
The kit of materials received by the client of "Guild of Engineering", which was commissioned by the hydrographic survey, include:
- Hidrográfico plan aqueous object in paper form (scale plan coordinated at step technical task preparation and approval).
- Upon customer request, extra conversion of the electronic version of the hydrographic documentation in the most convenient to it geographic information system format.