Everything you need to know about hydrography

1 Jul 2022 | Review Papers

Our guide to everything you need to know about hydrography

First of all, let's start by clarifying the concept of hydrography, used to refer to the branch of Earth science, responsible for measuring and describing the physical characteristics of natural elements such as oceans, seas, coastal areas, lakes and rivers, as well as predicting their changes over time.

The data obtained through hydrography are also used for primary purposes of navigation safety and as a form of support to all other marine activities, thus covering sectors such as economic development, security, defense of coastal regions, scientific research and the environmental protection of the regions.

What are hydrographic surveys used for?

Por norma, os levantamentos hidrográficos são realizados com o intuito de obter, entre outras informações, uma representação detalhada da topografia submarina de um local, através da batimetria. Este tipo de levantamentos compreende um conjunto de operações conduzidas em rios, barras, zonas costeiras e portuárias, para determinação das respetivas profundidades, tendo por base as recomendações da Organização Hidrográfica Internacional para a execução dos mesmos e produção de cartografia náutica.

In this sense, it is important to mention that the cartographic representation of a given area is made through nautical or hydrographic charts, and depending on the scale used, these can also display details of the relief of the coast, in addition to land information such as buildings, infrastructures and other notable points.

However, the diversity of use of hydrographic surveys does not stop there, because in addition to updating nautical cartography, this type of service also allows the creation of bathymetric models with possible applications in environmental, geophysical studies and engineering works.

How are these depths measured?

To determine depths, one of the tools that we can use is SONAR technology, and there is also the possibility of resorting to other techniques, such as aerial LiDAR, which can be used in shallow coastal areas, with the main advantage of being able to perform very extensive coverage in a short period of time, but in this case without the accuracy of SONAR.

Single Beam Systems vs. Multibeam

As we mentioned above, SONAR technology is used repeatedly for the preparation of hydrographic surveys, but it has several applications and is usually divided into single-beam and multi-beam systems:

  • Multibeam - requires more demanding logistics and allows total representation of the bottom, its use being indicated for ports where a total search is required for detection and characterization of objects.
  • Single-beam - performs the representation of the bottom in rows, with a spacing pre-defined by the hydrographer, and the smaller the spacing between rows, the longer the execution of the works becomes, but the spatial resolution of the bathymetric model is also greater, It is usually employed for jobs in shallow areas.

Main hydrographic characteristics of the Ria Formosa

The truth is that areas such as the Ria Formosa, which is located in the District of Faro, are candidates for Order 1 or 2 hydrographic surveys, that is, where a total search of the bottom is not required, but only the intention is to characterize the bathymetry for scientific purposes.

Neste sentido, entre os meses de Junho e Setembro de 2021, a LS Engenharia Geográfica realizou diversos levantamentos hidrográficos com recurso a sistemas de feixe-simples, tendo em vista a caracterização dos canais de navegação principal e secundário, próximos da barra de Faro-Olhão. Os dados obtidos, permitiram-nos fazer uma avaliação da hidrodinâmica do local e uma previsão acerca das zonas sujeitas a maior sedimentação num futuro próximo.

This and other services are at your entire disposal, carried out by an experienced technical team, so that you can make the best possible use of the data obtained. All you have to do is contact us and request a quote.