Environmental Degradation as a Risk Factor for Landslides in the Motozintla Basin, Chiapas, Mexico

Abstract:

Motozintla Basin is located southeastern Chiapas, Mexico. Most communities in this region are continously affected by landslides even some locations have disappeared because of this natural phenomenon. This study is focused on the communities that are located along the Xelajú river on this basin. The Motozintla basin has a triangular shape with an area of about 98.6 km². The slopes in the basin are abrupt ranging from 18° to 45° in about 72.11% of its area. The local altitudes range from 1,024 meters at the lowest point to 2,611 meters at the highest sites. These geomorphological features create unstable slopes which favors slow mass movements processes with different concentrations of sediment that can be transformed in sudden landslides. Many of these processes are accelerated by environmental degradation generated by human activities such as road constructions, land use changes from forest to agriculture or urban development. In this work we focus our research on determining how these human degrading actions increase the susceptibility of mass removal processes, mainly landslides. With this purpose, we generated a landslide inventory of our region of study for the period 1985-2014. We classified the landslides according to their origin (natural or man-made). Based on its location and the local characteristics, we could determine if the identified landslide was caused by natural or human actions. In addition, as environmental factors, we considered the land use characteristics and slope changes to determine the impact of the environmental degradation in the landslide susceptibility.