Presentation of changes in sea level at the port of Brest since the beginning of the 18th century at the REFMAR Days
The sea level is an important parameter used in studies on climate change. Brest is proud to have been one of the first sites in the world where systematic observations of sea level were conducted in 1679 by the French astronomers Picard and La Hire. Subsequently, sea level measurements continued, first under the leadership of the French Royal Academy of Sciences, then the Bureau des Longitudes and finally since 1846 by SHOM, which makes this port unique in the world. The observations show that the sea level has risen about 30 centimeters in 300 years. The mean sea level curve will be presented at the REFMAR Days.
Changes in sea level at Brest since 1711 from the work of Nicolas Pouvreau (SHOM, 2013)
Brest, a city open to the ocean, ideal for sea level observation
In his "Mémoire sur le flux et reflux de la mer" printed in 1789, scientist Pierre-Simon Laplace (1749-1827) presented the port of Brest "As one of the most favourable for tide observations [...] This port probably owes this advantage to its advanced position in the sea, and especially because its harbour has a very narrow entrance in relation to its size, and therefore the irregular oscillations of sea waters are greatly weakened". The geographical, geomorphological, bathymetric, anthropogenic, hydrological, meteorological and hydrodynamic characteristics explain why the city of Brest is an ideal natural observatory for observing the sea level.
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Why was the sea level measured in Brest in the past?
Understanding the laws of gravitation and trying to predict the tide
Until the mid-19th century, sea level measurements were commissioned by astronomers for two reasons: to understand the Newton's law of universal gravitation (1687) and to try to determine a method for predicting the tide. Great scientists like La Hire, Picard, Cassini II, Lalande, Laplace, Lévêque and Rochon all asked for sea level measurements to be taken in Brest during this period. And in fact, it was thanks to the sea level observations made between 1711 and 1716 that Laplace developed his Tidal Equations in 1799, which remained in use at SHOM until the early 1990s.
Creating nautical charts
In the early 19th century, Beautemps-Beaupré, Director of the Dépôt des Cartes et Plans (the current SHOM) invented "modern hydrography" in order to make navigation safe by providing accurate charts on which all the soundings were defined according to the lowest astronomical tide (standard still used today). To develop bathymetric charts, the hydrographic soundings must be corrected for the tide. This operation is called reduction of soundings. The nautical chart for Brest meeting these standards was issued in 1822.
Tide forecasts
In the late 1830s, the industrial revolution swept across France. The Dépôt des Cartes et Plans, future Service Hydrographique de la Marine, was a key element in this modernization. The advent of steamers greatly reduced the delivery time for goods. Predicting the tide at ports became a priority to determine the best times to load / unload merchandise. To meet this need, a network of ten tide gauges managed by the Ministry of Defense was set up starting in the 1840s, and the Dépôt de la Marine published the first tide table in 1839. It includes predictions for the port of Brest and a dozen other ports.
Why observe the sea level today?
Measuring water levels today is important for new reasons, including:
- safe navigation at port entrances,
- creating nautical charts,
- improving tidal predictions and hydrodynamic models,
- monitoring the rise in mean sea level to support the French plan for adapting to climate change (PNACC),
- calibrating satellite altimetry measurements (Jason 1, 2 and 3, Cryosat 2, Sentinel 3 satellites),
- providing valuable information for integrated coastal management (coastline, habitats,),
- statistical and historical studies of extreme levels and storm surges,
- forecasting information for coastal oceanography (Prévimer EuroGOOS),
- support for the national tsunami warning center in the Mediterranean and North-East Atlantic (CENALT) operated by the CEA in partnership with SHOM and CNRS,
- support to the storm surge and flood warning system operated by Météo-France in partnership with SHOM,
- etc.
How are changes in water level measured?
Originally sea level measurements were recorded by observers in registers. Water levels were read on tide staffs. In Brest, the tide staffs were installed at the exit of the dry docks.
In 1846, a tide gauge, a mechanical device for continuously measuring the sea level, was installed at the Brest naval base. It operated continuously until it was destroyed by Allied bombing in 1944. Reinstalled in 1952, this technology was used in Brest until the early 1990s.
Since then, the Brest tide gauge observatory has been equipped with digital gauges (first ultrasonic sensors and now radar sensors) as part of SHOM's RONIM network.
Presentation of the timeline at the REFMAR Days
A 4.40-meter poster will be on exhibit at the REFMAR Days (blue timeline above). SHOM experts will be on hand to answer any questions you may have.
Reference:
- Pouvreau N. (2008). Trois cents ans de mesures marégraphiques en France : outils, méthodes et tendances des composantes du niveau de la mer au port de Brest. Doctoral thesis, University of la Rochelle, defended on September 26, 2008, 466p.
To fin out more:
- Brest tide gauge observatory and water level measurements displayed in near real time
- Gauges and applications
- Construction of sea level records
- Tide Gauge Instrumentation (tide staff, analogue tide gauge, digital tide gauge)
- Presentation of the RONIM Network
- SONEL - Observation System for Long term Variations in Sea level
- 2019
- 2017
- 2016
- 2015
- 2014
- 2014_T4
- 2014_T3
- 2014_T2
- 2014_T1
- Rapport sur la caractérisation d'événements de tempêtes de l'automne-hiver 2013-2014 à partir des mesures marégraphiques
- Colloque - débat : réduire les risques littoraux et s'adapter au changement climatique La Rochelle 2-4 avril 2014
- New permanent tide gauge in Makemo - French Polynesia
- Impact of the storm Ulla on the sea level (14/02/2014)
- Report on the high tides and the effects of the low pressure system on 1 and 2 February and impact on sea level along the French Atlantic coast
- Annuaires des marées 2015 et SHOMAR édition 2014-2015 disponibles
- Sea level measurement by GPS buoys: the multisensor experiment on Aix Island
- coefficients des grandes marées 2014 calculées pour Brest
- egu 2014 sessions scientifiques s'appuyant sur les observations marégraphiques
- The effects of the low pressure system early this year on the sea level compared to other extreme events
- Compte rendu d'activité 2013 du GRGS
- Storms early this year and the impact on sea level in western France (2-5/01/2014)
- Impact of Cyclone Bejisa on sea level in Réunion Island (2 January 2014)
- 2013
- 2013_T4
- SHOM BATHYELLI: new datum product referenced to the ellipsoid on data.shom.fr
- Offre de formation à l'information géographique maritime et littorale
- Impact of the storm Xaver in the North Sea on the sea level in the Nord-Pas de Calais region (5-6/12/2013)
- Document sur l'Analyse statistique des niveaux d'eau extrêmes - Environnements maritime et estuarien
- Offre de stage : surfaces de références verticales marines. Analyse à partir de l'altimétrie spatiale et des données marégraphiques
- Retour sur le workshop du PSMSL organisé en marge de la session des experts GLOSS
- Journées nationales génie côtier génie civil JNGCGC juillet 2014 Dunkerque
- Offre de stage : Caractérisation des seiches portuaires le long du littoral français
- French review of the 11thsession of the Intergovernmental Coordination Group for the Tsunami Warning and Mitigation System in the North-eastern Atlantic, Mediterranean and connected seas
- French review of the 13thsession of the GLOSS Group of Experts and workshop commemorating the 80th anniversary of PSMSL
- The reference work on the theory and practice of tides online (in French and in English
- Courants de surface : questionnaire d'évaluation des besoins des utilisateurs proposé par l'OHI
- nouvelle édition du produit RAM 2013 SHOM
- 13ème session groupe experts GLOSS et 80ème anniversaire PSMSL
- Vidéos en ligne changement climatique et niveau de la mer ; Vulnérabilité côtière et enjeux sociétaux
- 2013_T3
- 2013_T2
- REFMAR Days 2013: We thank the 134 participants
- Presentation of changes in sea level at the port of Brest since the beginning of the 18th century at the REFMAR Days
- Deployment of a new RONIM tide gauge observatory in Port-la-Nouvelle (Mediterranean - Aude)
- Rapport annuel d'activité 2012 REFMAR
- Nouvelle fiche technique REFMAR Description d'une fiche d'observatoire de marée FOM
- 2013_T1
- Compte rendu d'activité 2012 du GRGS
- Languedoc Roussillon DREAL: producer of tidal observations and new partner of REFMAR
- coefficients de marée 2013
- Statistiques 2012 des niveaux marins extrêmes des côtes de France (Manche et Atlantique)
- Colloque coastal dynamics 2013
- Tidal observations of the tsunami generated by the earthquake off the Solomon Islands (Pacific Ocean) on February 6, 2013
- Colloque Hausse du niveau de la mer et risques côtiers - ANR CECILE
- Annonce 14eme Congres Francais de Sedimentologie
- Plan de mise en oeuvre 2012 du programme GLOSS
- Offre d'emploi docteur ou ingénieur chargé d'étude en reconstruction et analyse d'une série historique du niveau de la mer
- EGU 2013 sessions scientifiques s'appuyant sur les observations marégraphiques
- Offre stage estimation de l'évolution du niveau moyen de la mer à partir des mesures marégraphiques
- Colloque Evénements extrêmes d’inondation SHF
- 2013_T4
- 2012
- 2012_T4
- 2012_T3
- Un grand pas pour le système d’alerte aux tsunamis dans l’Atlantique du Nord-Est et la Méditerranée
- Report on the 9th session of the Intergovernmental Coordination Group for the Tsunami Early Warning System in the North-eastern Atlantic and Mediterranean
- International Conference on the digitization and preservation of analogue archives, including tidal archives
- Observation of a meteotsunami on July 27, 2012 in the Western Mediterranean
- Scientific presentations concerning variations in sea level, organized on line by the CNFGG
- Tidal predictions available using Android
- The French President visits the tide gauge stand at Tonnerres de Brest 2012
- Tide gauging technology at Tonnerres de Brest 2012
- 2011 Annual Report of REFMAR activity on lineEFMAR
- Tsunami alert centre (CENALT) operational
- 2012_T2
- Dissertation of Mr. Thomas Gouriou:
- Coordinating tsunami alerts in the Lesser Antilles (Source DEAL Guadeloupe)
- XIIème Journées Nationales Génie Côtier Génie Civil à Cherbourg
- Deployment of a new tide gauge observatory on the island of Saint-Pierre (Islands of Saint Pierre and Miquelon)
- Deployment of a new tide gauge observatory on Maré in New Caledonia (Maré in the Loyalty Islands)
- 9ème édition des journées scientifiques et techniques du CETMEF
- Pumping of freshwater partly to blame for the rise in sea levels
- Programme de recherche japonais sur des radars à tsunamis
- French assessment of the 7th meeting of the intergovernmental coordination group on the tsunami alert system in the Caribbean, under the auspices of UNESCO
- Effects on sea level measurement of the earthquakes occurring off the coast of Sumatra on 11 April 2012
- Installation of a new tide gauge at Port Ferréol (Les Issambres)
- An exceptional rise in sea levels revealed
- 2012_T1
- Publication of Volume 3 of the "The climate of France in the 21st century" series concerning the change in the sea level (MEDDTL / ONERC)
- Inventory action concerning the sea level data in Corsica
- EGU 2012
- Evolution des composantes du niveau marin en charente-maritime : soutenance de thèse
- Nouveau portlet REFMAR : le puits de tranquillisation
- Variations in the sea level along the length of the Western Tropical Pacific Islands
- Rapport d'activité quinquennal du GRGS 2007-2011
- Demi-journée scientifique organisée par le CNFGG portant sur les variations du niveau de la mer - 6 mars - Paris
- 34es journées de l'hydraulique portant sur les événements extrêmes fluviaux et maritimes - 1 et 2 février - Paris
- Assises nationales des risques naturels 2012 - 19 et 20 janvier - Bordeaux
- Tide gauge data exchange day in France within the framework of the CRATANEM project
- Inventory action concerning historical sea level data in paper format
- EGU 2012
- Coefficients de marée 2012
- Effect of the passage of cyclone Andrea on the sea level in France (5-6/01/2012)
- 2011
- 2011_T4
- New edition of the Maritime Altimetric References (RAM) product
- Report of the GIC/SATANEM in Santander, Spain - 22-24/11/2011
- French assessment of the 12th session of the GLOSS Group of Experts and associated workshops
- Sea level observations: a major cog in the establishment of a storm surge flooding warning system
- 12th session of the GLOSS Group of Experts and associated workshops [7-11/11/2011]
- XIIèmes journées nationales Génie Côtier - Génie Civil à Cherbourg
- Special edition of the 'Annales hydrographiques' hydrographic review dedicated to the observation and study of the sea level
- Slow subsidence of the island of Tahiti detected using, in particular, tide gauge data
- 2011_T3
- Janvier 2012 : Première édition des Assises nationales des risques naturels
- The sea level : Principal measure of the French plan for adapting to climate change
- Conférence : Have we reason to fear an increase in the level of the tide ?
- Observation of the mini-tsunami off Cornwall on 27 June by French tide gauges.
- Installation of a new tide gauge in New-Caledonia on the island of Lifou
- 2011_T2
- Very low tides on Monday 21 March 2011
- Low tide on the beaches of the west coast of La Réunion
- Installation of two tide gauges in New Caledonia
- Centenary of the SHF: Exterme maritime and fluvial events
- Installation of two new tide gauges at Ile Rousse in Corsica and in the port of La Figueirette (Théoule-sur-Mer)
- IAPSO Commission on Mean Sea Level
- Monitoring the tide gauges of the Marseille observatory
- Symposium on Vulnerability of Coastal ecosystems to global change and extreme events - At the crossroads of knowledge to the benefit of coastal and marine ecosystem services
- Conférence sur l'océanographie cotière operationnelle
- 2011_T1
- Modernisation of the tide gauge at Port-Tudy (Ile de Groix)
- Installation of a new tide gauge observatory on the Ile d'Aix
- Observations of the trans-Pacific tsunami on 11 March 2011 by the French Polynesia and New Caledonia tide gauges.
- Seiche in the port of Royan during the night of 15 to 16 February 2011
- Les multiples facettes du changement climatique (SMF)
- EGU 2011
- Summary of the Proceedings of the Seminar on Impacts of Climate Change on Coastal Risk organised by the BRGM in November 2010
- Issue of the new SHOMAR - Tidal predictions
- Article relating to observations of sea levels at Saint-Paul Island (Indian / Southern Ocean)
- Network of tide gauges in the Pacific
- 2011_T4
- 2010
- Installation of a new tide gauge in Monaco
- Installation of two new tide gauges in Corsica at Centuri and Solenzara
- 4th Workshop on Coastal Altimetry and OST-ST Meeting on Altimetry for Oceans and Hydrology
- Seminar on Impact of Climate Change on Coastal Risks
- Coastal areas at a time of climate change
- Draft plan for preventing marine inundation and flas floods
- Installation of a RONIM tide gauge at Fos-sur-Mer
- National coordination for the observation of sea levels
- Installation of a tide gauge at Toamasina
- Height of water observed by SHOM during the passage of storm Xynthia
- 2009
- 2008
- Installation of a tide gauge in Mayotte for the tsunami warning system in the Indian Ocean
- SHOM will take part in setting up a tsunami warning system
- Brest tide gauge : 300 years of observation
- Digitizing, transforming and validating paper records of sea level variations, called marigrams by NUNIEAU
- Radar tide gauges in France and monitoring of tide gauge-performance
- Modernisation Toulon and Nice tide gauges on 20 and 26 mai 2008