A probabilistic model for assessing debris flow propagation at regional scale: a case study in Campania region, Italy

<p>Debris flows and debris avalanches are rapid to extremely rapid landslides that tend to travel considerable distances from their source areas. Interaction between debris flows and elements at risk along their travel path may result in potentially significant destructive consequences. One of the critical challenges to overcome with respect to debris flow risk is, therefore, the credible prediction of their size, travel path, runout distance, and depths of erosion and deposition. To these purposes, at slope or catchment scale, sophisticated physically-based models, appropriately considering several factors and phenomena controlling the slope failure mechanisms, may be used. These models, however, are computationally costly and time consuming, and that significantly hinders their applicability at regional scale. Indeed, at regional scale, debris flows hazard assessment is usually carried out by means of qualitative approaches relying on field surveys, geomorphological knowledge, geometric features, and expert judgement.</p><p>In this study, a quantitative modelling approach based on cellular automata methods, wherein individual cells move across a digital elevation model (DEM) landscape following behavioral rules defined probabilistically, is proposed and tested. The adopted model, called LABS, is able to estimate erosion and deposition soil volumes along a debris flow path by deploying at the source areas autonomous subroutines, called agents, over a 5 m spatial resolution DEM, which provides the basic information to each agent in each time-step. Rules for scour and deposition are based on mass balance considerations and independent probability distributions defined as a function of slope DEM-derived values and a series of model input parameters. The probabilistic rules defined in the model are based on data gathered for debris flows and debris avalanches that mainly occurred in western Canada. This study mainly addresses the applicability and the reliability of this modelling approach to areas in southern Italy, in Campania region, historically affected by debris flows in pyroclastic soils. To this aim, information on inventoried debris flows is used in different study areas to evaluate the effect on the predictions of the model input parameter values, as well as of different native DEM resolutions.</p>

Understanding Temporal and Spatial Variation of Stable Water Isotopes in Precipitation over Upper Blue Nile River Basin

Stable isotopes in precipitation and vapor are a powerful tool for tracing the origin of moisture and mixing processes. This paper discusses time and space variation of δ18O in precipitation and controlling features over upper Blue Nile Basin using data from GNIP, observed data in 2014 and simulated data by AGCM. IsoGSM simulation in precipitation was verified with observation. The δ18O variation shows clear seasonality with the lowest 18O values in August and dry season, and enriched 18O in spring, June and September. Spring sample is enriched compared to summer, and assumed to be related with moisture sources. More enriched isotopes in spring and lower d-excess could be related to the source of air masses in short travel path from North Indian Ocean, Mediterranean and Red sea while summer rain is depleted with larger d-excess could be related to longer travel path of moisture from south Indian Ocean with mixing of potential evaporated moisture from open surface and transpired moisture from Congo vegetation and also from Gulf of Guinea. The isotopic statistics of three stations shows maximum, minimum and average value of (8.23‰, -11.73‰, 0.04‰) in Addis Ababa, (5.26‰, -12.74‰, and -2.52‰) in Entoto Hill and (4.08‰, -9.65‰, 2.41‰) in Debremarkos respectively. The δ2H- δ18O relationships, monthly weighted d-excess variation in the Basin revealed the temporal variation of δ18O in precipitation is essentially shaped by the source of the moisture and spatial differences is due to Rayleigh rainout effect along the moisture trajectory. The source of moisture is primarily controlled by the north south movement of ITCZ within the Basin. The study recommends the use of model simulated δ18O as good alternative for hydrological and hydrologeological investigations when needed.

Network analyses of foreign travellers through Wallachia, Moldavia and Transylvania between 1831-1840

"Foreign travelers backgrounds alongside journey routes followed into Romanian Lands between 1831-1840 were placed into a database and mapped into different geographical, social or chronological visualizations in a unique approach for Romanian historiography. Making use of Nodegoat, a platform that allows researchers to compile large databases and to analyze these data, relying on network-type connections, I created various easy-readable and modellable graphs which shows differences and similarities between travelers. Less effort is now needed for complex analysis which could have taken weeks or months back then, because all of these were made by the platform within few clicks with the help of various filters. Building profiles and comparing them, analyses traveler’s studies according to professions and seeking for their motivation behind journey and travel path followed are just some of the analyses made by this project. Even though it comprehend only 46 travelers from a decade this project have a great potential in near future by integrating all of the volumes coordinated by Paul Cernovodeanu into a single database. Keywords: foreign travelers, network analyses, geographical visualizations, social visualisations, Nodegoat "

Effect of Tactile Walking Surface Indicators on Travelers with Mobility Disabilities

Guidance tactile walking surface indicators (TWSIs), typically a surface of raised bars, are used internationally to provide location and directional information at crosswalks to pedestrians who are blind. The bars are installed across the sidewalk, with the bars perpendicular to the travel path on the sidewalk and parallel to the direction of travel on the crosswalk. In the U.S., there has been little or no use of such surfaces at crosswalks because of concerns about the effect of these bars on individuals with mobility disabilities. However, difficulties of blind pedestrians in locating crosswalks and aligning to cross have been documented, and the installation of surfaces with bars parallel to the direction of travel on the sidewalk has been shown to be a possible solution. This research investigated the effects of crossings of TWSIs installed perpendicular versus parallel to the direction of travel on the sidewalk on 38 participants with mobility disabilities who used a variety of mobility aids. Crossing either orientation of bars caused some increase in effort and instability for more than half of participants. Effort was somewhat greater on average for all participants when crossing bars perpendicular to their travel. Stability for wheelchair users was poorer, on average, when the bars were oriented perpendicular to their travel. There was low incidence of any slipping of feet or mobility aids, and low incidence of trapping of wheels or cane/crutch/walker tips. A significant majority of participants expressed their preference for crossing bars oriented parallel to their travel.