Conclusion
Friday 4 December 2009 by Thomas Lebourg

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So, the study of the La Clapière landslide movement with the help of mono frequency GPS enables to answer initial questions concerning the relevancy and quality of such monitoring. This reveals that in spite of the hostility of the environment the results are conclusive in term of accuracy as well as in term of robustness. Gamit indeed is not dedicated to calculations for a small network like the La Clapière-Rabuons one, but it allows to obtain reliable results, and above all, the quasi real time monitoring of the slide movements with the parameters that are here assessed as optimum.

Therefore in that case the GPS appears as a monitoring means fully complementary to targets. On smaller or more homogeneous landslides, it could quite constitute by itself an efficient monitoring and studying means. The data quality and the calculation robustness are globally better than those concerning the prisms, even if the GPS needs an excellent frame for data recovering. Its relevance from a financial point of view is not even the least, since the cost of a new tacheometer is ten to fifteen times higher than a mono frequency GPS one.

This pilot experiment being conclusive, other similar monitoring can be planned. It may rely on the RENAG network, as it were the case with the CLAP and RABU stations here. For this, it is admitted that a mono frequency calculation is reliable within a 30 kilometer radius from the point where the ionospheric corrections are assessed, i.e. within a 30 kilometer radius from the nearest dual frequency station. The RENAG and RGP networks therefore can be used as supports for other landslide studies. This is an interesting outlook for the future, for the development of mono frequency GPS monitoring for other natural phenomena.

Publications

- N. Martin (1995), Surveillance topométrique du glissement de la Clapière, Saint Etienne de Tinée : valorisation des mesures angulaires automatiques, Rapport du CETE Méditerranée

- F. Didier (1994), Surveillance topométrique du glissement de la Clapière, Saint Etienne de Tinée : Calcul des coordonnéees Lambert des cibles à partir de mesures automatiques, Rapport du CETE Méditerranée

- S. Jules (1993), Glissement de la Clapière, Saint Etienne de Tinée : Détermination des coordonnnées cartesiennes des cibles à partir de la télémesure automatique des coordonnnées polaires, Rapport du CETE Méditerranée

 
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