Determination of Areas Susceptible to Landsliding Using Spatial Patterns of Rainfall from Tropical Rainfall Measuring Mission Data, Rio de Janeiro, Brazil

Renato Guimarães,Harvey Greenberg,Márcio Cataldi,Osmar De Carvalho,David Montgomery,Roberto Gomes,Wátila Machado,Pedro Mendonça

doi:10.3390/ijgi6100289

Abstract

Spatial patterns of shallow landslide initiation reflect both spatial patterns of heavy rainfall and areas susceptible to mass movements. We determine the areas most susceptible to shallow landslide occurrence through the calculation of critical soil cohesion and spatial patterns of rainfall derived from TRMM (Tropical Rainfall Measuring Mission) data for Paraty County, State of Rio de Janeiro, Brazil. Our methodology involved: (a) creating the digital elevation model (DEM) and deriving attributes such as slope and contributing area; (b) incorporating spatial patterns of rainfall derived from TRMM into the shallow slope stability model SHALSTAB; and (c) quantitative assessment of the correspondence of mapped landslide scars to areas predicted to be most prone to shallow landsliding. We found that around 70% of the landslide scars occurred in less than 10% of the study area identified as potentially unstable. The greatest concentration of landslides occurred in areas where the root strength of vegetation is an important contribution to slope stability in regions of orographically-enhanced rainfall on the coastal topographic flank. This approach helps quantify landslide hazards in areas with similar geomorphological characteristics, but different spatial patterns of rainfall.

Highlights

Mass movements occur at a variety of spatial and temporal scales, influencing hillslope evolution in high-relief areas [1], and posing a significant hazard in upland regions
We identified from orthophotos 46 landslide scars, most of which occur on the escarpment, and which all together occupy 18 ha, corresponding to 0.02% of the total area
Orographic rainfall is a major influence on landslide initiation along the passive margin escarpment of Southeastern Brazil

Summary

Introduction

Mass movements occur at a variety of spatial and temporal scales, influencing hillslope evolution in high-relief areas [1], and posing a significant hazard in upland regions. Precipitation and slope steepness influence shallow slope failures within the weathering mantle that generally fails to a depth conditioned by the soil and saprolite/rock strength and root reinforcement. Such translational landslides in the highlands of the state of Rio de Janeiro are common and have caused numerous fatalities in recent years. The combination of heavy summer rains and the lack of urban planning creates high landslide disaster potential in the region where growing cities face possible loss of life and material damage

Methods

Results

Discussion

Conclusion