Landslides Triggered by the May 2017 Extreme Rainfall Event in the East Coast Northeast of Brazil

Nikolai S Espinoza,Jason Giovannettone,Manoranjan Mishra,Cláudio M Santos E Silva,Maria L Da Silva,Celso A G Santos,Carlos A C Dos Santos,Rosaria R Ferreira,Cristiano P De Oliveira,Venerando E Amaro,Helber B Gomes,João Medeiros,Madson T Silva

doi:10.3390/atmos12101261

Abstract

Given the increasing occurrence of landslides on the East Coast Northeast of Brazil (ECNEB), it is essential to understand its conditions and triggering factors because meteorological anomalies triggered by a landslide will threaten life and property in the region. In this sense, this research aimed to diagnose the meteorological conditions that triggered landslides in the ECNEB in May 2017, evaluate the terrain’s intrinsic conditions using elevation, slope, and susceptibility parameters and determine critical precipitation thresholds for the city with the highest number of landslide risk areas in the region. A dynamic downscaling experiment was carried out using the Regional Climate Model (RegCM) to verify the ability of this model to represent rainfall over the ECNEB. The results from the intrinsic factors showed that the ECNEB is highly susceptible to landslides with various high-risk sectors for landslides to the population. The extreme rainfall event was associated with the convergence of humidity at low levels over the ocean, which contributed to landslides in the ECNEB, mainly in the State of Pernambuco, where 67 landslides were registered. The RegCM numerical simulation underestimated the high daily rainfall signal seen on the Tropical Rainfall Measuring Mission satellite. It is suggested that sensitivity tests can be performed using other physical parameters to find the best model configuration for the ECNEB. This work recommends that exploring the relationship between precipitation and landslides will provide objective criteria for assessing risk areas by contributing to the predictability of disasters in this region.

Highlights

Analyses focused on the consequences of future climate change point to a trend that there may be an increase in the number of extreme rain or drought events in various susceptible areas of the Earth, especially in regions with high population density [1,2].it becomes relevant to understand which agents are triggering points for the cause of these extreme events and to mitigate their effects.In Brazil, rapid and disorderly urbanization mischaracterizes the natural landscapes, forcing low-income populations to occupy unfavorable geological-geomorphological areas for their livelihood
The extreme rainfall event used in this study which occurred at the East Coast Northeast of Brazil (ECNEB) in May
From 24 to 31 May, 71 landslides were registered in ECNEB, i.e., one in Paraíba, three events in Alagoas, and 67 landslides in Pernambuco (Figure 4)

Summary

Introduction

Analyses focused on the consequences of future climate change point to a trend that there may be an increase in the number of extreme rain or drought events in various susceptible areas of the Earth, especially in regions with high population density [1,2].it becomes relevant to understand which agents are triggering points for the cause of these extreme events (e.g., drought, floods, and landslides [3]) and to mitigate their effects.In Brazil, rapid and disorderly urbanization mischaracterizes the natural landscapes, forcing low-income populations to occupy unfavorable geological-geomorphological areas for their livelihood. Analyses focused on the consequences of future climate change point to a trend that there may be an increase in the number of extreme rain or drought events in various susceptible areas of the Earth, especially in regions with high population density [1,2]. Basic instruments of urban development and expansion policy, or the Land Use and Occupation Law, which includes policy related to the prevention of landslides [4]. This combination of factors correlated with the absence of permanent public policies that prioritize disasters has increased the population’s vulnerability to floods and landslides. Inadequate forms of urban occupation, mainly for residential purposes, have contributed decisively to transforming stable natural areas into high-risk sectors for landslides [7]

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