The implantation of the Geodetic Permanent Tide Gauge Network (RMPG) was initiated by the IBGE 15 years ago, with the objective of contributing to the correlation between data concerning bathymetry (depth of the oceans) change in the sea level and terrestrial altitudes, as well as other information and geodetic and oceanographic models.

The IBGE is responsible for establishing and keeping the Brazilian Geodetic System. In this system, more than 70 thousand points have high-precision altitudes defined based on the Mean Sea Level (MSL), that is, the average of the observations of the sea level measured by marigraphs installed along the coast. Therefore, all maps of the terrestrial portion of the Brazilian territory present altitudes counted from the mean sea level.

On the other hand, for the nautical charts, which show the submarine territory of Brazil, the 'zero' depth is not the mean sea level, but the so-called reduced level (RL), which corresponds basically to the minimum sea level, specific of each coast region, aiming at meeting the strict international criteria of navigation safety.

This difference between mean sea level and reduction level leaves a great variation along the coast, which makes it difficult to carry out coastal construction works and prevents the rigorous quantification of flood risk on the coast caused by the rise of the sea level and by meteorological extremes.

The report “Mean sea level analysis in the Geodetic Permanent Tide Gauge Network - 2001/2015” presents the treatment given to data and preliminary results relative to the 2001-2015 period, contributing to the discussion on the necessity of the environmental monitoring for mitigating the effects of global changes and helping us adapt to them.

The IBGE releases today the report “Mean sea level analysis in the Geodetic Permanent Tide Gauge Network (RMPG) - 2001/2015”. The report's preliminary results point to a mean sea level rise in the RMPG stations, mainly in the South and Southeast, probably due to more extreme meteorological effects, as low pressures, winds, storm surge, etc.

Another important factor is the vertical movement of the Earth’s crust, i. e., of the influence of the Earth level. The IBGE has already installed GNSS receivers (Global Navigation Satellite Systems), such as the GPS, to monitor the probable movements of the Earth’s crust and of constructions in the surroundings of marigraphs, and will, eventually, carry out the revision of sea level data.

The information produced by the tide gouge network is useful for several applications, as the reduction of drilling for the conservation and expansion of the capacity of ports and waterways, the implantation of infrastructure (ports, roads, water and sewerage networks) in coastal areas and mitigation of the impacts related the global sea level rise.

The report also presents new procedures in data treatment and control of monitoring equipment, aiming at a permanent enhancement of the vertical component of the Brazilian Geodetic System (SGB). A new station was installed in Belém (PA) and two others had their pressure sensors substituted by radar sensors: Santana (AP) and Imbituba (SC). These three stations, now, are meteorogical and tide gauge stations combined, as they are equipped with electronic independent sensors for sea level observation, with almost real-time transmission via GSM, and meteorological sensors.

Click here and access the report “Mean Sea Level Analysis in the Geodetic Permanent Tide Gauge Network (RMPG) - 2001/2015”, in PDF format.

The implantation of the Geodetic Permanent Tide Gauge Network (RMPG) was initiated by the IBGE 15 years ago, with the objective of contributing to the correlation between data concerning bathymetry (depth of the oceans) change in the sea level and terrestrial altitudes, as well as other information and geodetic and oceanographic models.

The IBGE is responsible for establishing and keeping the Brazilian Geodetic System. In this system, more than 70 thousand points have high-precision altitudes defined based on the Mean Sea Level (MSL), that is, the average of the observations of the sea level measured by marigraphs installed along the coast. Therefore, all maps of the terrestrial portion of the Brazilian territory present altitudes counted from the mean sea level.

On the other hand, for the nautical charts, which show the submarine territory of Brazil, the "zero" depth is not the mean sea level, but the so-called reduced level (RL), which corresponds basically to the minimum sea level, specific of each coast region, aiming at meeting the strict international criteria of navigation safety.

This difference between mean sea level and reduction level leaves a great variation along the coast, which makes it difficult to carry out coastal construction works and prevents the rigorous quantification of flood risk on the coast caused by the rise of the sea level and by meteorological extremes.

The report “Mean sea level analysis in the Geodetic Permanent Tide Gauge Network - 2001/2015” presents the treatment given to data and preliminary results relative to the 2001-2015 period, contributing to the discussion on the necessity of the environmental monitoring for mitigating the effects of global changes and helping us adapt to them.