HYDROGRAPHIC SURVEY

A hydrographic survey is conducted in order to chart and/or map the shorelines and bottom depths of waterways such as streams, rivers, lakes, reservoirs, and oceans. This type of survey is also necessary for navigation and for the development of water resources for various purposes like flood control, irrigation, electrical power, and water supply. Like other special surveys, several different types of electronic and radio-acoustical instruments are used in hydrographic surveys.

These special devices are commonly used in determining water depths and location of objects on the bottom by a method called taking SOUNDING. Sounding are taken by measuring the time required for sound to travel downward and be reflected back to a receiver aboard a vessel

Most surveys are primarily concerned with water depth.The nature of the sea floor material because of the implications for anchoring, dredging, structure construction, pipeline and cable routing and fisheries habitat.SONAR (SOund NAvigation and Ranging) uses sound waves to find and identify objects in the water and to determine water depth.The data is collected and processed digitally with specialized computer systems that store the data in digital form.