Atmospheric corrections for topographic monitoring systems in landslides.

SUMMARYNew automated “long range” total stations are actually available for monitoring landslides, dams, structures etc. The use of total station is consolidate within some hundred meters of distance and with a supervisor. But the long range (up to 3 km) measurements are not still completely investigated in operating condition. When the accuracy and the precision required are important, seems to be necessary to investigate the atmosphere influence on distance measurements. The research deals with the study of a landslide topographic monitoring system: the Collagna Landslide (Reggio Emilia, Italy) monitoring system. It consists of an automated long range total station acquiring about 36 prisms ,every 4 hours, since 2009. The idea was to test how atmospheric corrections could improve the measurements precision and accuracy to exploit the system capabilities. Some tests on the total station EDM (Electronic Distance Measuring) system are presented in operating conditions. Particularly attention was paid to the long distances dependence on atmospheric conditions (temperature, pressure and relative humidity). Two kinds of corrections were applied, that of the instrument and one of the literature. Some differences were found on atmospheric corrections calculated with the two different methods. But it seems that atmospheric corrections can really improve the final result accuracy.