AN OVERVIEW OF A GIS METHOD FOR LANDSLIDE MAPPING, ASSESSING LANDSLIDE SUSCEPTIBILITY, AND ESTIMATION OF LANDSLIDE SEDIMENT YIELDS ON THE SE FLANK OF PICO DE ORIZABA VOLCANO, MEXICO
The Río El Estado watershed on the SE flank of Pico de Orizaba volcano covers 5.2 km2 with elevations ranging from 2,677 to 4,248 m a.s.l. and slopes between 5° and 68°. The stream system of El Estado erodes Tertiary and Quaternary lavas, pyroclastic flows, and ash fall deposits. Geologic and geomorphologic factors, high seasonal precipitation, severe weathering, and steep slopes predispose the study area to landslides. The methodology encompasses three main stages of analysis: Stage 1 builds a historic landslide inventory and its spatial geo-database based on aerial-photo-interpretation and local field surveys.
Stage 2 calculates and compare the landslide susceptibility by using heuristic (per landforms), statistic (Multiple Logistic Regression), and cartographic-hydrologic (SINMAP) methods.
Stage 3 estimates the potential total landslide material volume delivered to the main stream drainage channel by using an empirical area-volume relationship.
We estimate that landslides have the potential to deliver 27,677,303 m3 of sediment to the main stream, 83% of this volume is contributed by high susceptibility landforms. We present the technique and its implementation of each stage in GIS. The results allow us to understand the long-term evolution of the fluvial system on southwestern flank of Pico de Orizaba.