Abstract

GALINDO SERRANO, José Alejandro  and  ALCANTARA AYALA, Irasema. Slope instability and road infrastructure: susceptibility analysis of mass movement processes in the Sierra Nororiental, Puebla, Mexico. Invest. Geog [online]. 2015, n.88, pp.122-145. ISSN 2448-7279.  https://doi.org/10.14350/rig.43790.

In Mexico and around the world, disasters associated with slope instability generate negative impacts on the socio-economic and environmental contexts. Besides the loss of life and damage to vegetation cover, the damages to homes and infrastructure are common. In recent years, the destruction and deterioration of road infrastructure has been of particular importance.

The Sierra Norte de Puebla is among the different áreas of the country that are recurrently affected by slope instability. Direct and indirect human and economic losses result of the occurrence of mass movement processes (MMP) -mainly triggered by heavy rains- in vulnerable exposed communities in this region, have taken place since some decades. The impact on infrastructure has become important, especially since 1999. Therefore, this study is focused on the analysis of susceptibility to mass movement processes on the main roads of the Northeast region of the Sierra de Puebla.

This analysis involved the development of an inventory of MMP as well as of the thematic maps used as input for the implementation of multi-criteria and weights of evidence analysis. Two maps of susceptibility of the region of interest were obtained and the results were analyzed by a recurrence index of MMP. Finally, the spatial analysis of susceptibility to MMP for several road sections of the Sierra Nororiental, based on the analysis of proximity and overlap, was made.

The inventory was generated based on two procedures. The first was through direct observation in the field and data collection by using a global positioning system (GPS). The second was through remote sensing using SPOT satellite images and Google Earth. The inventory included 166 landslides and 40 potentially unstable areas.

According to the recurrence index of MMP developed in order to analyze the produced maps, results obtained by applying the method of weights of evidence, showed that 72.28% of MMP occurred in the ranges of high and very high susceptibility, 24.1% in areas of medium susceptibility and 3.6% in the low range. The MMP categorized as low range were caused by human factors, and were situated in slope cuts or artificial excavations of small dimensions, which due to map scale and the interval of contour lines were not properly represented.

Moreover, according to the multi-criteria analysis, 69.27% of MMP were located in the range of high and very high susceptibility, 23.49% are in areas of medium susceptibility and the remaining 7.22% were concentrated on low and very low areas of susceptibility. MMP that are in the low range are of small size and result from the constructions and cuts for roads, that is to say, to factors or parameters that were not considered directly in this analysis.

The high susceptibility áreas correspond to áreas with very rugged terrain, while the fíat regions coincide with áreas of very low susceptibility. The variation of the results expressed in the susceptibility maps produced by applying both methodologies implies that the zoning of multi-criteria analysis tends to produce lower values in urban areas, while the weight of evidence, conferred lower values to mountain areas that can be centeracterized as potentially unstable due to its geological-geomorphological nature, but lacks of records or concrete evidence.

This study represents a first step in the analysis of slope instability triggered by rainfall in the road infrastructure in the Sierra Nororiental de Puebla (North Eastern Range of Puebla). It is therefore important that future studies of multidisciplinary nature and especially the contribution of civil engineering perspective consider the interaction between the physical environment and road infrastructure. As such, it will be of great significant to address issues including slope cutting height, angle of slope, drainage works cleaning, type of cross section of the road, functionality of the retention works, type of soil and rock, rock fractures, discontinuities, the level of cutting of vegetation coverage, erosion processes, and rainfall- infiltration dynamics.

Keywords : Mass movement processes; susceptibility; road infrastructure; multi-criteria analysis; weights of evidence.

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