Important things you need to know about hydrographic surveying

Hydrographic surveying is the survey of physical features found underwater. This is the science of measuring the factors underwater that affect all marine activities such as marine construction, dredging, offshore drilling, and so on. It is mainly done through sounding, sensors, and electronic sensor systems for shallow water. The information obtained from the survey is needed to bring up various nautical charts. These charts involve improved channels, available depths, piers, breakwaters and aids for navigating harbour facilities. The survey takes part in the necessary collection of data related to the developments and construction of port facilities. This helps us to find the loss in due capacity to silt and other uncertainties.

Application

Hydrography is applied in different fields. Some of the most popular applications of this type of survey include irrigation, dock and harbour engineering, land reclamation, river works, flood control, water, and sewage disposal.

Uses

Hydrography is used for different purposes such as determining the depth of the bed and shoreline, and preparing navigation charts. It can also be used to locate sewer falls and locate mean sea level. Hydrography can be used for tide measurement and identifying silting, scouring and irregularities. It can also be used to measure the stream and river discharge and plan massive structures such as dams and bridges.

Preliminary steps in hydrography

The method starts by locating special control points found along the shoreline. The sound method is then employed to determine the depth of various points. This is usually done utilizing stationary boards. A hydrographic surveying agency can then make sound locations from a boat or by fixing a point in the boa. Certain preliminary steps are made before this procedure. The first step is reconnaissance. The second step is locating the horizontal control and the third step is locating the vertical control.

The first step – reconnaissance

Reconnaissance has to be undergone as every project needs a startup plan for efficiency and affordability. A complete reconnaissance of the whole survey area is done to choose the best area for the survey. This facilitates satisfactory completion of the survey while adhering to the specifications and requirements governing such work. The study could benefit a lot from aerial photographs.

Locating horizontal control

It is necessary to locate the horizontal control to locate all features of the marine and land in a true relative position. This leads to a series of lines whose azimuths and lengths are determined by way of triangulation or other methods. A plane table survey and tachometric can be conducted to undergo rough work. There are no rules for establishing horizontal control because the vegetation, topography, size and type affect the rules.

Locating the vertical control

This is a very important step in hydrographic surveying. It is important to establish vertical control before the sounding. A lot of benchmarks are put in place to serve as vertical control. Checking and setting the levels of the gauges are some of the uses of benchmarks. Sounding in the survey comes after locating the vertical control.