The extent of the fault damage zone remains an outstanding challenge confounding attempts to assess rock mass physical and mechanical properties, the effects on landscape evolution and slope stability, and to delineate safe places for human occupation and infrastructure development. Quantifying the relationship between faulting and the spatial geometrical and mechanical characteristics of a rock mass controlled by faulting is difficult, mainly because of varying lithology and rock mass characteristics, the effects of topography and vegetation and local erosion of weaker rock mass. Recent technological developments including Unmanned Aerial Vehicles, terrestrial laser scanning, photogrammetry and point cloud analysis software tools greatly enhance our ability to investigate the issues using the Yarlung Tsangpo (YLTP) Fault of southern Tibet as a case study where ideal geological conditions exist to investigate the relationship. In this study, the procedures, investigation approaches, evidence and criteria for defining the threshold distance for damage zones of YLTP Fault of southern Tibet were studied quantitatively by combining the spatial variations of fracture density, rock mass strength, rockfall inventory and previous thermal evidence. The results have been compared with published data from the evidence of thermal effects related to the exactly the same fault and show a good match between internal thermal action and rock mass physical and mechanical properties controlled by the same faulting. The extent of threshold distance of damage zone of the YLTP Fault is estimated as 5.9±0.6km. Within the damage zone, fracture density and cohesion of the rock mass show power curve relations with distance from the YLTP Fault. The internal dynamic action of fault controls rock mass physical and mechanical properties in the study area. The fault first affects the characteristics of rock mass structures, and then the orientation of the rock structures influences the stability of slope leading to rockfall.

Attaining a comprehensive and reliable water balance of snow-dominated alpine catchments is fundamental for a holistic representation of the hydrological and hydrogeological processes. A major limitation to the elaboration of this balance in alpine terrain is the difficultly of data acquisition as well as the limited presence of meteorological stations. Remotely sensed data can provide valuable information for the balance elaboration at a regional scale. We exploited Sentinel-satellite data to estimate the groundwater storage for one hydrologic year in an extensive Alpine catchment located in northern Italy. Evapotranspiration (ET) and Snow Water Equivalent (SWE) were estimated once weekly with the combined use of Sentinel data, at a spatial resolution of 20 m and 30 m, respectively. Finally, the groundwater storage was estimated by means of the residual water balance approach. The results show that the adopted satellite-based methods allow obtaining consistent and physically realistic values to describe the groundwater storage dynamics, with a relatively low uncertainty (36%). For the studied hydrologic year, a positive storage occurred only in the snowmelt period and the overall storage was negative, leading to a lowering of the groundwater level in the floodplain. In addition, the influence of physiographic parameters (altitude, slope, and aspect) and the seasonal conditions on the estimates of ET and snow-depth were investigated. For SWE estimates, an altitude-dependent effect and a lower accuracy in the snowmelt phase were observed. Finally, the estimated values of ET and the SWE-linked components were verified for a gauged tributary valley with negligible groundwater storage.