Modeling landslide volume using geomorphologic analysis in the southern flank of Pico de Orizaba Volcano, Mexico

In this research, the relationship between surface area and volume of landslides in a volcanic watershed is presented, together with the geomorphological analysis of landforms that may lead to slope instability. The use of this method allows a better understanding of the potential landslide volume contribution along homogeneous units. The analysis is supported by Geographic Information Systems (GIS), the use of drones, and statistical techniques to create a comprehensive method for landslide volume estimation for each landform. This approach is applied to the Rio Chiquito-Barranca del Muerto watershed on the south flank of Pico de Orizaba volcano, Mexico. The watershed is prone to gravitational processes because of its physical geographical conditions (highly weathered volcanic and sedimentary deposits that form hilly and steep terrains which are affected by extreme seasonal precipitation) and anthropogenic conditions (deforestation and land use change). In the area, more than six hundred landslides were mapped and grouped into different forms of relief. In the study area, representative landslides were measured in detail with the help of a drone to establish an empirical relationship between the area of the landslide and its volume. This relationship, expressed as a power law with a scale exponent, was used to estimate the potential contribution of the material produced by the landslides in each form of the relief already pre-established in the basin. The study shows that the method can be useful in remote places with difficult access and sparse topographic information. It also shows that sedimentary landforms contribute with more sediments per square kilometer, even though, they have less landslides than the volcanic landforms.