# Monitoring and Data Analysis in Small-Scale Landslide Physical Model
## 6 Conclusions  
A series of three tests in small-scale physical model was performed in a sandy slope to observe landslides initiation and development using noncontact displacement measurements, as well as classical geotechnical monitoring sensors, only in their miniature dimensions. Landslide changes during initiation and development were monitored by observations of volumetric water content, temperature, and displacements within the slope model. In all tests, although the time to failure was different because of different rainfall intensities and different initial moisture, failure occurred by the rising of the ground water level which reduced suction and effective stresses in the foot of the slope. After the initial crack formation in the lower part of the slope, further landslide development manifested with retrogressive distribution. Results of displacements and volumetric water content allow a landslide initiation and development reconstruction. Results from the terrestrial laser scanning, although highly precise, could be complemented with the SfM photogrammetry if the latter's accuracy is improved by the higher resolution and number of images, better lighting, and use of static reference points for georeferencing. As for the high-speed camera, by nature of the test, some data will most certainly be lost in the sliding, but using two camera systems instead of one could prove extremely valuable in gaining more results with better accuracy. If possible, reference markings resistant to the rainfall should be installed, and all the interference from the elements of the physical model removed or reduced to minimum. The use of miniature sensors such are soil moisture sensors, soil potential sensors, and accelerometers at certain points in the sliding body present the critical parts necessary to assemble the whole picture from landslide initiation, development to the failure in the end. Although some equipment mentioned in the paper was not completely used in this series of tests, i.e., tensiometers, the measurement results give insight into the landslide behavior of sandy slopes exposed to artificial rainfall. Preliminary analyses show that the best approach for landslide monitoring is an integrated approach using both noncontact optical measurements and miniature sensors built-in within the landslide body. Eliminating sources of errors would provide better results for future tests in the small-scale landslide physical model. The most accurate results can be obtained by combining noncontact measurements with the results of built-in instruments which provide insight into the conditions leading up to the initiation of a landslide process. Further experiments will include tests with different rainfall patterns and different drainage boundary conditions which will give us better insight into the landslide behavior, as well as the ability to integrate results from the geodetic and geotechnical monitoring equipment and their use as a validation in numerical modeling. Conceptualization, Z.A. ; methodology, Z.A., V.J., J.P., N.C. and S.P. ; formal analysis, J.P., S.M. and Z.A. ; investigation, Z.A., V.J., J.P., N.C. and S.P. ; resources, Z.A. ; writing--original draft preparation, S.P. and Z.A. ; writing--review and editing, Z.A., S.P., J.P. and N.C.; visualization, S.P. and S.M. ; supervision, Z.A. ; project administration, Z.A. and S.P. ; funding acquisition, Z.A. All authors have read and agreed to the published version of the manuscript. This research was funded by Croatian Science Foundation under the Project IP-2018-1503 Physical modeling of landslide remediation constructions behavior under static and seismic actions (ModLandRemSS). These supports are gratefully acknowledged. The part of the laboratory equipment used for laboratory testing was provided in the frame of the Project Research Infrastructure for Campus-based Laboratories at the University of Rijeka, co-funded in a part by the Ministry of Science, Education, and Sports of the Republic of Croatia and the European Regional Development Fund (ERDF).