Post-Wildfire Landslide Hazard Assessment: The Case of The 2017 Montagna Del Morrone Fire (Central Apennines, Italy)

Carabella Carabella,Miccadei Miccadei,Paglia Paglia,Sciarra Sciarra

doi:10.3390/geosciences9040175

Carabella Carabella, Miccadei Miccadei + Show 2 more

Open Access

https://doi.org/10.3390/geosciences9040175

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Journal: Geosciences	Publication Date: Apr 16, 2019
Citations: 49	License type: CC BY 4.0

Affiliation: University of Chieti-Pescara

Abstract

This work focused on a post-wildfire landslide hazard assessment, applied to the 2017 Montagna del Morrone fire. This wildfire increased the possibility of landslides triggering, as confirmed by the occurrence of a debris flow, triggered by an intense, short duration rainfall event in August 2018. The study area was investigated through a detailed analysis incorporating morphometric analysis of the topography and hydrography and geomorphological field mapping, followed by the landslide hazard assessment. In detail, the analysis was performed following a heuristic or expert-based approach, integrated using GIS technology. This approach led to the identification of five instability factors. These factors were analyzed for the construction of thematic maps. Hence, each factor was evaluated by assigning appropriate expert-based ranks and weights and combined in a geomorphology-based matrix, that defines four landslide hazard classes (low, moderate, high, and very high). Moreover, the morphometric analysis allowed us to recognize basins prone to debris flows, which, in relevant literature, are those that show a Melton ratio of >0.6 and a watershed length of <2.7 km. Finally, all the collected data were mapped through a cartographic and weighted overlay process in order to realize a new zonation of landslide hazard for the study area, which can be used in civil protection warning systems for the occurrence of landslides in mountainous forested environments.

Highlights

Wildfire is a natural process in forest ecosystems and occurs with varying frequency and severity depending on landscape features and climatic conditions and is believed to have been relatively common since the late Devonian times [1]
As known in the thematic literature [2,3,81,82] the primary geomorphic consequences of wildfires are dry ravel and root strength decline; the decrease in vegetation cover leads to an increase in the infiltration rate that appears to favor the initiation of mass movement, as directly shown in the study area following the occurrence of the August 2018 debris flow
This paper presents a post-wildfire landslide hazard assessment realized following a multidisciplinary approach, which involves morphometric analysis, rainfall data analysis, geomorphological field mapping, and geomechanical investigations

Summary

Introduction

Wildfire is a natural process in forest ecosystems and occurs with varying frequency and severity depending on landscape features and climatic conditions and is believed to have been relatively common since the late Devonian times [1]. It can be considered as a geomorphological agent, whose activity can vary enormously and depends on an interplay of factors including topography, geology, vegetation cover, fire characteristics, and rainfall patterns [2,3,4]. It is necessary to integrate and adapt the general knowledge, which is commonly based on the field assessment of geological and geomorphological settings, and slope stability to the analysis of post-wildfire situations, which is the first step in preventing further post-fire disasters [23]

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