Hydrographic Or Bathymetric Surveying

Hydrographic surveying or bathymetric surveying is the survey of physical features present underwater. It is the science of measuring all factors beneath water that affect all the marine activities like dredging, marine constructions, offshore drilling etc.
Hydrographic surveying is mainly conducted under authority concerns. It is mainly carried out by means of sensors, sounding or electronic sensor system for shallow water.
The information obtained from hydrographic surveying is required to bring up nautical charts which involves,
Available depths
Improved Channels
Breakwaters
Piers
The aids to navigation harbor facility
These survey also take part in necessary data collection relating to construction and developments of port facilities, such as pier construction. This help in finding the loss in capacity due to silt and many uncertainties.
Applications of Hydrographic Surveying
Following are the applications of hydrographic surveying:
Dock and Harbor Engineering
Irrigation
River Works
Land reclamation
Water Power
Flood Control
Sewage Disposal
Uses of Hydrographic Surveying
Uses of hydrographic surveying are given below:
1. Depth of the bed can be determined
2. Shore lines can be determined
3. Navigation Chart Preparation
4. Locate sewer fall by measuring direct currents
5. Locating mean sea level
6. Scouring, silting and irregularities of the bed can be identified
7. Tide measurement
8. River and stream discharge measurement
9. Massive structures like bridges, dams harbors are planned.
Sounding in Hydrographic Survey
The process of determining depth below water surface is called as sounding. The step before undergoing sounding is determining the mean sea level. If the reduced level of any point of a water body is determined by subtracting the sounding from mean sea level, hence it is analogous to levelling.
The specific need for sounding are
1. Preparation of navigation charts that is an all-time information for future purpose also
2. Material that to be dredged has to be determined early to facilitate easy movement in project without any confusion
3. Material dredging should also accompany where filling has to be done. Material dumping is also measured
4. Design of backwaters, sea wells require detailed information that is obtained from sounding
Equipment for Sounding
The essential equipment used for undergoing sounding are
1. Shore signals and buoys
2. Sounding Equipment
3. Instruments for measuring angles.