Rainfall thresholds for the initiation of shallow landslides in Nuevo Leon, Mexico.

Abstract:

The influence of rainfall on the occurrence of landslides depends on many factors such as landslide dimensions, kinematics or material involved. It is widely recognized that shallow landslides are usually triggered by short intense storms. Nuevo Leon state located in northeast Mexico is highly prone to the occurrence of this kind of slope failures due to its geologic, geomorphologic, climatic attributes and location, being targeted by tropical cyclones during the Atlantic hurricane season. A database of rainfall events that have resulted in shallow landslides on the region was compiled; the data indicated that there is a coincidence between the occurrence of shallow landslides and extreme rainfall events. A threshold curve in the form of I= αD^-β was established to describe the threshold in where I is the rainfall intensity by rainfall event in mm/day and D is the duration of rainfall event in days. Duration of the rainfall events that triggered shallow landslides ranged from 2 to 5 days, with maximum intensity of 236 mm/day and a minimum intensity of 57.7 mm/day. From the data analyzed we could obtain a regression value of I = 109.77D-1.76 and established a new minimum rainfall intensity-duration threshold for the initiation of rainfall-induced shallow landslides that can be used for the development of a early warning system in Nuevo Leon, Mexico