Comparative analysis of the SHALSTAB model from 1:10,000 and 1:50,000 scales

Landslides are natural phenomena that model the terrain and cause great damage to humanity, both financially and in terms of loss of life. Therefore predicting this phenomenon is extremely important as it can lead to better city planning and a more effective preventative containment work. Of the various scientific models proposed to date, the SHALSTAB model stands out. It combines a hydrological model and a hillside instability model (based on the Infinite Slope equation). SHALSTAB has been obtaining very good results in areas of the western United States and also in tropical areas. The objective of this work is to define in the terrain, areas more sensitive to landslides and analyze the efficiency of the model using topographical data of different scales. To do this it is necessary to generate a digital elevation model and obtain geomorphologic parameters (such as slope and contribution area) in order to identify the risk areas in the terrain. A high-resolution photogrammetric enlarger was used to create a 1:10,000 scale map of landslide source areas, run off tracks, and deposits. This was then georeferenced to the high resolution DEM. The SHALSTAB performance was verified comparing the unstable pixel in the fall within landslide scat´s. The results show that the 80% of the SHALSTAB performance from 1:10,000 scale topographic data was located in unstable classes. However, the model performance from 1:50,000 scale decreases to 50%. In addition, the performance from 1:10,000 scale just 1% of the scar fall at stable class on the other hand around 18% fall in this class when a 1:50,000 scale is used. Thus, we suggest that greater effort and emphasis should be placed on acquisition of high-resolution, high quality topographic. A 50,000 scale can be used in order to determine preliminary landslides hazard areas but it is necessary to have a 1:10,000 scale to increase model performance in critical areas.