Réseau Bases GNSS RTK “Low Cost” pour le littoral

Dans le cadre du projet AGEO et de l’observatoire OSIRISC sur les risques côtiers, des bases GNSS  RTK “Low cost” sont en cours d’installation sur le littoral pour inciter les collectivités locales concernées à suivre l’évolution de leur littoral et du trait de côte. L’IUEM participe à la recherche et aux développements des solutions technologiques et méthodologiques grâce aux actions conjointes des membres du LETG, du LGO et du P2I. Une base RTK “Low cost” est opérationnelle depuis l’IUEM. Des tests compatibilités ont été réalisés avec des équipements RTK mobile comme des récepteurs GNSS “low cost”  et TOPCON ainsi que les drones DJI Phantom 4 RTK et Mavic 2 Entreprise Advanced RTK.
Ce réseau de base GNSS pour le littoral de Bretagne Occidentale s’appuie sur le projet CENTIPEDE qui vise à créer un réseau de bases RTK ouvertes et disponibles pour toute personne se trouvant dans la zone de couverture (~50 km) .

Pour en savoir plus sur les projets :

Projet AGEO (Atlantic GEOhazard Platform) est un projet cofinancé par le programme Interreg Espace Atlantique via le Fonds européen de développement régional (FEDER).
Observatoire de la vulnérabilité aux risques côtiers d’érosion et de submersion en Bretagne (pilote OSIRISC de l’Université de Bretagne Occidentale).
https://www.risques-cotiers.fr/connaitre-les-risques-cotiers/projets/ageo/
Projet CENTIPEDE réseau de bases RTK  : Le réseau est étendu par des instituts publics, des particuliers, des acteurs privés comme les agriculteurs ou d’autres partenaires publics.
https://docs.centipede.fr/

 

Projet MoVeGra

Project  “Mobile Underwater Vector Gravity Sensor” (MoVeGra)

The objective of MoVeGra is to mature the technology of a novel type of vector gravity sensor to be used on Autonomous Underwater Vehicles (AUV). This proposal is the follow-up of a larger project, GRAVIMOB, which developed and built the first prototype and tested it during a cruise (GRAVIMOB 2016, funded by the French Oceanographic Fleet-FOF).

the objectives of ANR research axis 01 as this new sensor will allow:

  • improving the knowledge of the crustal structure (porosity, alteration) and fluid circulation associated with hydrothermal vents, which impact the fluxes of diverse elements, and,
  • evaluating the economic potential of the mineral deposits associated with these environments.

The concept of GRAVIMOB is based on direct measurements of accelerations along three axes (De Saint Jean, 2008). The system is composed of six accelerometers mounted in two co-linear triads, integrated on a glass sphere, which also holds the data loggers and additional sensors (Figure 1). It is therefore a vector gravity meter allowing, after data processing, to determine the three components of the gravity acceleration.

GRAVIMOB sensor (left), sphere in a frame for AUV AsterX (centre), AUV AsterX (right) AUV AsterX @IFREMER

Main partners: LGO  ESGT (Le Mans)

Collaborations: IGN, SHOM, IFREMER
Prototype built by  MAPPEM Geophysics, funded by CPER Bretagne

Test cuise GRAVIMOB (NO Europe, AUV AsterX), May 2016, funded by FOF, Labex MER, LGO

Cruise evaluation (CNFH)

Cruise operational report

Cruise scientific report

Test cruise GRAVIMOB-2 (NO Europa, AUV) evaluated A+ by the French Coastal Fleet Committee (CNFC)

Cruise evaluation (CNFC)

Bibliography

Roussel, C., J. Verdun, J. Cali, M. Maia, and J. F. d’EU. “Integration of a strapdown gravimeter in an autonomous vehicle.” ISPRS – International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL– 5/W5 (April 9, 2015) : 199–206. doi :10.5194/isprsarchives-XL-5-W5-199-2015

Thèse (DGA): Roussel, C. Expérimentation d’un gravimètre mobile léger et novateur pour la mesure du champ de gravité en fond de mer, 2017 (https://tel.archives-ouvertes.fr/tel-01635884)

Offshore observation

Offshore observation

Offshore observation


Dans le cadre de l’Observatoire des Sciences de l’Univers de l’IUEM, le laboratoire maintient deux réseaux acoustiques hauturiers pour la surveillance acoustique de la sismicité océanique et des grandes baleines :

  • OHA-SIS-BIO dans l’océan Indien
  • HYDROBS-MOMAR dans l’océan Atlantique (sud des Açores)

Chacun de ces observatoires acoustiques met en œuvre un réseau d’hydrophones, autonomes entre 12 et 18 mois, destinés à capter la sismicité de faible magnitude associée aux régions actives du plancher océanique (dorsales, failles transformantes, sites hydrothermaux) qui sont trop éloignées des réseaux sismologiques terrestres.

L’objectif est d’acquérir des séries temporelles continues, les plus représentatives possibles de l’activité tectonique et magmatique « de fond » des structures actives. Cette ambition reste toutefois entièrement tributaire de ls disponibilité des moyens navals nationaux pour la maintenance annuelle de ces réseaux.

Ce service d’observation travaille à :

  • l’automatisation du traitement des données et à la mise à disposition de catalogues d’évènements acoustiques pour la communauté scientifique
  • la valorisation vers le grand public des résultats les plus spectaculaires
  • l’élargissement de la communauté des utilisateurs, en partie réalisée par la surveillance acoustique conjointe des grandes baleines
  • des travaux de recherche amont sur l’origine des ondes acoustiques (conversion des ondes sismiques en ondes acoustiques sur le fond de l’océan) et sur la propagation longue distance des ondes de basse fréquence.

Compléments d’information

Légende de la figure

Les hydrophones (rectangle jaune) sont immergés dans l’axe du canal SOFAR, couche océanique à faible vitesse du son dans laquelle les ondes acoustiques basse fréquence peuvent se propager sur plusieurs milliers de kilomètres.
La ligne de mouillage est composée d’un lest perdu (maillons de chaine), d’un largueur acoustique, d’une ligne de plusieurs millers de mètres, et d’une bouée (Photo) qui abrite l’instrument. La ligne est ajustée de façon à ce que le capteur soit immergé dans l’axe du SOFAR ( entre 800 et 1200m de profondeur selon la latitude).


Coastal Marine Observation

Coastal Marine Observation

Coastline Observatory


Coastline Observatory

The coastal zone is a high-stakes area for the coming years, particularly given the consequences of climate change (sea-level rise, more intense storms, even more frequent). In fact, coastal areas, particularly the coastline, are highly progressive areas with eroding areas sometimes several meters per year for soft shores. They are expected to suffer increased sea assaults during storms, increasing the intensity of erosion and causing submersions for low-lying areas that are damaging to local populations and the local economy.

The long-term observation of the evolution of this area is therefore a major challenge in which the Ocean Domains Laboratory in close collaboration with the Geomer laboratory is fully involved via the SOERE Observation and Experimentation Systems, in the long term. , for Environmental Research “Dimensioning” labeled since 2010 by Allenvi.

SOERE “Coastline” is an observation network, multi-site and integrated, on the three coastal facades metropolitan. It is managed by the universities of Brest, Caen and Montpellier, in collaboration with regional academic and public partners (General Councils, regional, Dreal, DDTM, …).

The objective is to perpetuate the long-term time series, to harmonize the observation strategies between the laboratories, to implement modern means of measurement for an observation integrated at the same time of the evolution of the object ” coastline “and basic dynamic forcing parameters. Coastal topography data, transformed into Digital Terrain Models (DTMs), provides basic information for the development of numerical or even physical modeling to initiate prospective research oriented towards the future of coastal systems.

The measurements made are mainly topographic, bathymetric and sea level measurements made with the laboratory’s means:   

  •   Multi-beam sounders (SMF)   
  •   Terrestrial Laser Scanner (TLS or Lidar)  
  •   Surveying equipment (differential GPS)    
  •  Onboard instruments and DRELIO imager drone

Observatory of Erosion in the West Indies (ObsErA)

The Oceanic Domains laboratory is also involved in the Observatory of Erosion in the West Indies (ObsErA) which is an observation service of the INSU-CNRS and the Institute of Physics of the Globe of Paris devoted to the study of alteration and erosion in the West Indies.

Member of the Research River Basin Network and the Critical Zone Observatory Network, it involves teams from the Institute of Physics of the Globe of Paris, the Volcanological and Seismological Observatory of Guadeloupe, the University Antilles-Guiana, the laboratory Oceanic domains (UBO) and the Earth Sciences Laboratory of Claude Bernard University (Lyon I).

The objective of ObsErA is to allow the creation of a database of water flows (precipitation and river flow), sediment flows and organic matter (in particular carbon) in rivers and on rivers. and the chemical composition of rivers and soils in the particular context of the island of Basse-Terre in Guadeloupe, marked by a tropical climate and active volcanism. This database will enable the scientific community to study and quantify modes of chemical and physical erosion, as well as their impact on the environment (soil composition, river chemistry, carbon flux, etc.). To date, ObsErA follows the evolution of 3 watersheds located within the Guadeloupe National Park: Capesterre, Bras-David and Vieux-Habitants.

Link to the ObsErA website


Coastal topography data, transformed into Digital Terrain Models (DTMs), provides basic information for the development of numerical or even physical models to undertake prospective research on the future of coastal systems. The measurements made are mainly topographic, bathymetric and sea level measurements made with the laboratory’s means:

  • Multi-beam sounders (SMF)   
  • Terrestrial Laser Scanner (TLS or Lidar)    
  • Surveying equipment (differential GPS)     
  • Onboard instruments and DRELIO imager drone

Observatory of Erosion in the West Indies (ObsErA)


The Ocean Geosciences Laboratory is also involved in the Observatory of Erosion in the West Indies (ObsErA), observation service of the INSU-CNRS and the Institute of Physics of the Globe of Paris devoted to the study of the alteration and erosion in the West Indies.

As a member of the Network of Research Basins and the Critical Zone Observatory Network, this observatory involves teams from the Institute of Physics of the Globe of Paris, the Volcanological and Seismological Observatory of Guadeloupe, the University Antilles-Guyana, the Ocean Geosciences Laboratory (UBO) and the Earth Sciences Laboratory of Claude Bernard University (Lyon I).

The objective of ObsErA is to create a database of water flows (precipitation and river flow), sediment flows and organic matter (especially carbon) in rivers and on slopes as well as the chemical composition of rivers and soils in the particular context of the island of Basse-Terre in Guadeloupe, marked by a tropical climate and active volcanism. This database will enable the scientific community to study and quantify chemical and physical erosion modes and their impact on the environment (soil composition, river chemistry, carbon flux, etc.). To date, ObsErA follows the evolution of 3 watersheds located within the Guadeloupe National Park: Capesterre, Bras-David and Vieux-Habitants.

Link to the ObsErA website

On-land Observation

Terrestrial Observation

Permanent Accelerometric Network


The Permanent RAP Accelerometric Network is a national network of instruments that record ground motion caused by earthquakes. It centralises the data and makes them available to all actors involved in the analysis of hazard and seismic risk. The RAP is a component of RESIF, a French seismological and geodesic network.

Les stations  du RAP sont regroupées en réseaux régionaux gérés par des organismes et établissements publics ayant pour vocation l’observation sismologique. L’ UBO, au travers de notre laboratoire, est en charge du sous-réseau RAP-UBO avec l’Université de Bretagne Sud et l’Université de Nantes, qui comprend  4 stations: UBBR, UBQP, UBVA et UBNA.

Map of regional seismicity


This map of instrumental seismicity of Finistère was made from the Si-Hex catalog published by the French Seismological Central Office from 1964 to 2009 and from the catalog of the LDG / CEA from 2009 to 2013.

It shows a weak to moderate seismicity with magnitudes Mw of 1 to 4.3. Nearby seismological stations, which have helped locate earthquakes, are represented by a triangle. There are three in the region, which does not allow to obtain a precise location of earthquakes.

The main seismogenic faults of Finistère are:     

  • the South Armorican shear,     
  • the shear of the Black Mountains,    
  •  the shear of the Monts d’Arrée    
  •  and the Elorn Fault.

The topographic background of the map was made from topographic data of SHOM and IGN. Contacts: Julie Perrot & Christine Authemayou