Hydrographic Surveying Process: Measurement of Underwater Topography

The hydrographic surveying process can be described as the measurement of underwater topography. This process determines and measures subsurface forms, irregularities, different structures, and features using various instruments lowered into the water and sonar technology.

Features of the Measurement Equipment and Differences from Terrestrial Surveying Instruments

During underwater surveys, specially designed and customized measurement devices are used instead of conventional terrestrial surveying instruments. These devices are manufactured to withstand varying underwater conditions, depths, and challenges, and are specifically designed to detect and measure the topography and geographic features of the seabed.

Measurement Process and the Use of Echo Sounders

The fundamental principle generally used in the measurement process is based on the reflection of acoustic signals transmitted underwater by a specialized device mounted on a vessel, known as an echo sounder. The reflected signals are collected and analyzed. The data obtained from these signals are recorded via a GPS receiver integrated into the echo sounder. This receiver ensures that underwater measurements and collected data are associated with accurate, real-time positional information.

Data Collection and Map Production Process

At the end of the process, all data are collected. Subsequently, these data are processed and analyzed. The post-collection phase does not differ from the classical map production process. In other words, the collected data constitute the raw material required for map production. Using these data, a map containing detailed and accurate information about the surveyed area is produced. Thus, this process plays a vital role in better understanding and analyzing the seabed and various underwater topographies.