Resilience of Railway Transport to Four Types of Natural Hazards: An Analysis of Daily Train Volumes

A crucial step in measuring the resilience of railway infrastructure is to quantify the extent of its vulnerability to natural hazards. In this paper, we analyze the vulnerability of the German railway network to four types of natural hazards that regularly cause disruptions in German rail operations: floods, mass movements, slope fires, and tree falls. Using daily train traffic data matched with various data on disruptive events, we quantify the extent to which these four types of natural hazard reduce daily train traffic volumes. With a negative binomial count data regression, we find evidence that the track segments of the German railway network are most vulnerable to floods, followed by mass movements and tree-fall events. On average, floods reduce traffic on track segments by 19% of the average daily train traffic, mass movements by 16%, and tree fall by 4%. Moreover, when more than one type of natural hazard affects the track segment on the same day, train traffic on that segment falls by 34% of the average train traffic. Slope fires have an ambiguous and nonrobust effect on train traffic due to the reverse causality due to its triggering factors. This is the first study that attempts to rank different natural hazards according to their impact on railway traffic. The results have implications for the selection of resilience strategy and can help prioritize policy measures

Debris-flow activity and snow avalanches in a steep watershed of the Valais Alps (Switzerland): Dendrogeomorphic event reconstruction and identification of triggers

Debris flows and snow avalanches are common processes in the headwaters of steep watersheds worldwide. In forested areas, dendrogeomorphic analyses of trees affected by debris flows and snow avalanches have regularly been used to date past events. Previous studies have, however, almost never focused on both processes at once, as snow avalanche impacts cannot easily be distinguished from debris-flow scars. In a similar way, tree-ring studies have often been limited to conifers, and sites colonized with broad-leaved forests have been widely disregarded. We report on a case from the Valais Alps (Switzerland) where past debris-flow and snow avalanche activity was dated with intraseasonal precision using different broad-leaved and conifer trees. In total, the analysis of 171 cores, 34 wedges, and 11 crosssections from 93 trees allowed identification of 20 debris-flow and 3 snow avalanche events between A.D. 1930 and 2008. Results also indicate that some of the events would have been missed without the sampling of broad-leaved trees

Reduced Temperature Sensitivity of Maximum Latewood Density Formation in High-Elevation Corsican Pines under Recent Warming

Maximum latewood density (MXD) measurements from long-lived Black pines (Pinus nigra spp. laricio) growing at the upper treeline in Corsica are one of the few archives to reconstruct southern European summer temperatures at annual resolution back into medieval times. Here, we present a compilation of five MXD chronologies from Corsican pines that contain high-to-low frequency variability between 1168 and 2016 CE and correlate significantly (p < 0.01) with the instrumental April–July and September–October mean temperatures from 1901 to 1980 CE (r = 0.52−0.64). The growth–climate correlations, however, dropped to −0.13 to 0.02 afterward, and scaling the MXD data resulted in a divergence of >1.5 °C between the colder reconstructed and warmer measured temperatures in the early-21st century. Our findings suggest a warming-induced shift from initially temperature-controlled to drought-prone MXD formation, and therefore question the suitability of using Corsican pine MXD data for climate reconstruction

Oxygen and hydrogen stable isotopic composition of precipitation, creek, and underground water on Corsica (France) 2017-2019

In this study several water compartments (precipitation, creek, soil) were sampled over a two-year period on a bi-weekly basis from April 2017 to April 2019 and analyzed for the temporal variations of their oxygen and hydrogen stable isotope ratios (δ18O and δ2H) at five sites over an elevation gradient from sea level to around 1600 m a.s.l. on the Mediterranean island of Corsica (France). Sampling site code is composed of the mountain ridge side (W for west, E for east) and the approximate elevation (L for low, M for mid, H for high). Precipitation was collected via evaporation-free, tube-dip-in water precipitation collectors (Palmex d.o.o., Zagreb, Croatia). Creek water samples were taken mid-stream. Where possible, soil suction probes were installed at around 80 to 100 cm depth. If the topsoil layers were too thin or rocky and a soil probe installment was not possible, water from roadside springs and fountains, or rockface seeps was sampled. Probe, fountain, and seep water are referred to as 'underground' water