Monthly Archives: February 2018

Caroline Lefeuvre: Influence des effets thermiques dans l’e valuation de l’ale a chute de blocs

Caroline Lefeuvre
Co-supervisors: Prof. Michel Jaboyedoff, Dr. Marc-Henri Derron

Les aléas liés aux mouvements gravitaires sont des phénomènes très présents en zone de montagne. Parmi ceux-ci, il est possible de nommer les glissements de terrain, les laves torrentielles, les avalanches rocheuses, ou encore les chutes de blocs. Un aléa est caractérisé par sa probabilité, ou fréquence d’occurrence, son intensité et sa localisation.

Ce travail se concentre sur l’étude des chutes de blocs. Le terme chute de blocs désigne en général un aléa de faible intensité, mettant en jeu la chute de faibles volumes de blocs rocheux inférieurs à 10000m3 (Dussauge-Peisser et al, 2002). C’est un aléa qui peut potentiellement menacer des enjeux tels que des habitations ou des réseaux routiers. C’est donc la raison pour laquelle le risque chute de bloc est étudié.

Si l’intensité de l’aléa chute de blocs est plus ou moins connue, de par sa définition, il est important d’étudier la quantification de la probabilité d’occurrence de l’aléa afin de bien comprendre l’aléa. De nombreuses études ont été menées sur les facteurs pouvant provoquer des chutes de blocs. Le déclenchement d’un événement de chute suite à des conditions météorologiques particulières a été intensément étudié. Par exemple, Delonca et al. (2014) et D’Amato et al. (2016) ont analysé l’influence des précipitations. L’influence des variations de température a été examinée à travers les cycles gel dégel (Frayssines & Hantz, 2006) et les cycles thermiques (Collins & Stock, 2016 et Vargas et al., 2013). Les secousses sismiques sont également des facteurs déclenchant de chute (Bakun-Mazor et al., 2013). Enfin, des déformations tectoniques peuvent causer des fractures dans la roche (Scholz, 1968), ce qui génère des zones de faiblesse dans la roche.

Dans le cadre de ce travail, l’aspect fréquence de l’aléa chute de bloc sera principalement étudié, notamment à travers l’influence des variations de températures au sein de la roche, étant susceptibles de créer une fatigue thermique des roches. En effet, de récents travaux ont montrés que les variations journalières de température génèrent des déformations cycliques, mesurées au niveau d’écailles rocheuses (Collins & Stock, 2016). Ce travail a pour but de modéliser l’impact des conditions thermiques sur la déformation et la fatigue des roches, pouvant conduire à la déstabilisation de petits blocs.

Le site d’étude utilisé pour ce travail est une paroi rocheuse située dans la commune de Bourg-en-Lavaux, à environ 10km de Lausanne (Vaud, Suisse). Les chutes de blocs provenant de cette paroi ne menacent pas d’enjeux. Cependant l’activité élevée de chutes en fait un site d’étude idéal. Les blocs sont en moyenne de la taille du mètre cube. De plus, la zone d’étude bénéficie de nombreuses instrumentations. En effet, le site est équipé d’une station météo, d’un capteur thermique dans la roche et d’un appareil photo. Les données recueillies avec ces derniers ont servis de comparaison avec les résultats de la modélisation.

Amenan Agnès Kouame: Apport de la modélisation hydrogéologique dans l’étude des risques de contamination de la nappe d’Abidjan par les hydrocarbures: Cas du benzène dans le District D’Abidjan

Amenan Agnès Kouame
Directors: Prof. Michel Jaboyedoff and Prof. Albert Goula Bi Tié
Jury: Prof. François Zwahlen, Dr. Marc-Henri Derron, Dr. Jean Kouame Kan, Prof. Erkman Suren

This study on the aquifer of the Continental Terminal is carried out in the Abidjan District located on the coastal sedimentary basin in southern Côte d’Ivoire (West Africa). This unconfined aquifer of the city of Abidjan of Mio-Pliocene age is called “Abidjan groundwater”. The water quality of this aquifer is facing with diverse sources of anthropogenic pollution such as scattered deposits of solid and liquid wastes of all kinds. Indeed, the inadequacy of sanitation and drinking water supply systems increases the pollution risk of the Abidjan’s groundwater. Besides, the proliferation of petrol stations, including tank breaking, needs to be considered in the event of an accident, which poses a real threat to groundwater given the complex hydrogeological structure of the region. In order to ensure the effective protection and management of the Abidjan water table, this work proposes to evaluate the risk of contamination of groundwater in the Abidjan aquifer by hydrocarbons such as benzene for the purpose of the implementation of protective measures. To achieve such an objective, a model of underground flow and contaminant transfer was designed from field data and literature. Soil analysis showed two types of soils: sand and silty sand. Using the FEFLOW software, the predictive simulation of underground flow coupled with the transport of dissolved benzene deposited on the soil surface at the N’Dotré and Anador station was implemented. Dissolved benzene initial concentrations are 43.12 and 14.17 mg/l for the two sites respectively for variably saturated zone. The results revealed that a borehole named ZE11 of the “Zone Est”capture field is polluted after 44 years and 2 months because the threshold concentration of 0.001 mg/l is reached. A maximum concentration of 0.011 mg/l is reached at this drilling at 47 years and 2 months. In this zone, 5 other wells in this Zone, ZE1, ZE7, ZE8, ZE13, ZE14 are threatened by pollution because the dissolved benzene was detected after a time ranging from 39 to 46 years. The ZE10 has even recorded a maximum concentration of 0.0008 mg / l in 46 years. The average distance from Anador site these is 4 km. At an average distance of 2 km from the N’Dotré service station, 8 boreholes belonging to the Anonkoua Kouté, AK15 AK5, AK6, AK7, AK8, AK10 AK4 and AK17, are also threatened by pollution, dissolved benzene has been detected. for a time between 38 to 47 years.

With the software, HYDRUS, for an initial concentration of 2 mg/cm3, the dissolved benzene sets 105, 112 and more than 365 days to cross the 100 cm cylinder of sand, silty sand and clay respectively, taking into account the delay. Without delay, these times are reduced to 100, 80 and 50 days respectively for clay, silty sand and clay. Considering the sand material, the pollutant takes more than 7 years to cross the average thickness of the unsaturated zone 56 m.

During its journey, if the pollutant crosses channels, these global times could be 10 to 100 times shorter. Therefore, special attention should be given to the sites of N’Dotré and Anador in case of rupture of the tank especially as this tablecloth of Abidjan is the only source of drinking water in the District of Abidjan. The method of decontamination of the unsaturated zone proposed is “bioventing” taking into account the high percentage of sand that constitutes the soil of the District of Abidjan geological formations.

Liliane Nguyen: Identication de précurseurs synoptiques aux évènements de précipitations extrêmes pour des situations de Sud dans les Alpes par l’analyse des trajectoires inverses

Liliane Nguyen
Supervisors: Dr. Pascal Horton, Prof. Michel Jaboyedoff

One of the most expensive natural disasters in Switzerland consists of floods related to heavy precipitation. Moreover, the occurrence of heavy rains may induce landslides and debris flows as it was observed during the three major precipitation events that occurred recently in the Swiss Alps (August 1987, September 1993 and October 2000). Even though all these inclement weather conditions took place under a southerly circulation, especially in autumn, not all southerly circulations lead to heavy precipitation. Although many studies have been carried out to understand them, they are still very difficult to forecast, due to the complexity of the phenomena involved. In consequence, the forecasting of extreme events still contains important uncertainties, especially in an alpine environment. The numerical models struggle to take into account the complexity of this environment strongly influence by different local-scale specific behaviors. Therefore, this work aims to identify simple synoptic precursors to such events throughout backward trajectories of the air masses.

Backward trajectories can be modeled with different methods and along two or three dimensions. The 2D trajectories are calculated and projected on an invariant parameter such as the pressure or the temperature, while the 3D trajectories indicate the height position of the air masses. Backward trajectories are calculated by using wind fields provided by different meteorological datasets, such as atmospheric reanalysis. In order to process trajectories, various tools already exist. Nowadays, backward trajectories have become very popular in the atmospheric science. In consequence, multiple tools and
datasets are provided by different organizations.

Therefore, this work is separated into two parts. Part one test and compare as many combinations of tools, datasets and methods as possible in order to gain knowledge about trajectories in the case of heavy precipitations in the Alps and to reduce the number of models to be assessed for the second part. As a result, we removed models yielding to similar results with an absolute horizontal transport deviation measure (ATEH). Among them, we tested tools such as the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), a simple Matlab script developed at the University of Lausanne by Pascal Horton named HorTraj and the METeorological data Explorer (METEX). The implemented methods in these models are different: while HYSPLIT and METEX use a Lagrangian Particle Dispersion Model, HorTraj uses the fully implicit algorithm of Merril (1986). Since these tools can be used with various datasets, the trajectories are processed with different ones such as the NCEP/NCAR Reanalysis (R1, R2 & C20r), the ECMWF reanalysis (ERA40 & ERAinterim), the Japanese Reanalysis (JRA-55) and the NASA Reanalysis (MERRA2). Moreover, for each tool and dataset, various methods can be used to calculate the altitude of the air masses. In this work, three-dimensional, isobaric, isentropic, isosigma, constant density and from divergence trajectories have been used. As a result, 21 trajectory models have been tested and compared, and 9 of them were selected. Results show that the larger differences between trajectories have been mainly from the dataset used rather than the model.

Then in part two, the 9 selected models were used to search simple precursors leading to heavy precipitations. 10 days backward trajectories were processed for the Binn station (which is a gauging station that often measures big amount of rain) on four levels pressure between 1000 and 500 hPa. As for the validity domain, we selected all the days included between 1961 and 2014 that were characterized by a southerly circulation in autumn. Based on those trajectories, part two suggests four analysis for the identification of precursor. First, the ATEH is used to assess similarities between extreme events and non-extreme events. Then a Lagrangian moisture source diagnostic is suggested to determine the origin of moisture contributing to precipitation. A residence-time probability analysis is also suggested to highlight area where the residence-time probability is greater than the average probability associated with typical meteorological patterns. Finally, last analysis presents an identification of special type of flow conditions, such as the stagnation, recircultation and ventilation that can enhance extreme precipitations.

Results show that trajectories leading to heavy precipitation tend to be similar than trajectories leading to dry or small events. Region of interest that highly contributes to heavy precipitations have also been highlighted, such as the western Mediterranean and North Africa.

Geoffroy Leibundgut: Analyse de mouvements de versants rocheux et quantification des risques induits le long de la vallée de la Grande-Eau, Suisse: Le phénomène de débâcle

Geoffroy Leibundgut
Supervisor: Prof. Michel Jaboyedoff
Co-supervisor: Jérôme Tixier

La nuit du 23 février 2014, un bloc rocheux de 100 tonnes se décroche et percute un chalet de montagne dans le village d’Isola (Alpes Maritimes, France). Deux enfants sont tués sur le coup. Le 22 mars 2014, un glissement de terrain spontané survient à Oso (Washington, USA) tuant 41 personnes et détruisant près de 49 foyers et autres infrastructures. Le 2 mai 2014, le village d’Abi Barik (province de Badakhshan, Afghanistan) est complétement détruit par deux glissements de terrain consécutifs. Environ 350 personnes sont tuées, 2 500 disparues et plus de 1 000 foyers sont affectés (chiffres tirés du blog internet de l’équipe risque de l’institut ; http://www3.unil.ch/wpmu/risk/).

Les dangers naturels sont au coeur de notre quotidien. Les chiffres énoncés plus haut montrent à quel point l’homme est vulnérable à ces évènements bien souvent aléatoires et difficilement prévisibles. La liste n’est pas exhaustive et on décompte déjà plus de 400 personnes décédées depuis le début de l’année 2014 à cause de ces 3 événements naturels. Dans un contexte où l’on s’attend à voir venir des changements climatiques importants influençant encore plus les mécanismes déclencheurs de mouvements de terrain (précipitations intenses dans certaines parties du globe, fonte des glaciers, etc.), il est plus que nécessaire de prendre en compte les risques liés aux dangers naturels dans nos sociétés et politiques. Le risque fait l’objet d’avancés importantes dans le domaine de la recherche. Des outils de mesures et d’analyses toujours plus performants et la vitesse accrue du développement informatique permettent une analyse et une caractérisation des processus dangereux de qualité à l’heure actuelle. Si la recherche s’attache à développer le savoir scientifique autour des mécanismes naturels dangereux pour mieux les prévenir, les politiques actuelles intègrent, de plus en plus, la notion du risque dans leur gestion du territoire. On voit apparaitre la mise en place de plans de prévention et de plans d’alertes dans les communes. Des politiques de sensibilisation voient également le jour. Autant d’éléments qui permettent, de nos jours, d’avoir une vision intégrée des risques naturels afin de mieux les prévenir et de mieux les gérer en cas de crise.

C’est en ce sens que s’inscrit ce projet. Il s’attachera à étudier deux types de dangers naturels imbriqués sur une zone d’étude particulière le long de la vallée de la Grand Eau, Suisse. A savoir, seront caractérisés, l’aléa d’instabilités rocheuses, autrement dit, la production de chutes de blocs et compartiments rocheux en zone de forte déclivité, puis l’aléa de création d’un barrage naturel dû au dépôt de ces blocs rocheux dans le lit de la rivière (appelé un embâcle) et la rupture potentielle de cette retenue d’eau (appelé débâcle). L’étude se proposera enfin de quantifier les risques d’inondation induits sur la ville d’Aigle en aval.

Ce travail s’articule donc en deux temps. D’abord, on caractérise l’aléa d’instabilités rocheuses. Plusieurs approches sont utilisées pour essayer de quantifier le danger présenté par la zone active. Une place importante sera laissée à la discussion. Ensuite, dans une approche prévisionnelle, il convient de créer des scénarios d’instabilités rocheuses pour simuler des cas de création d’embâcle. L’aléa embâcle/débâcle sera analysé pour plusieurs scénarios et enfin seront quantifiés les risques induits en aval pour les événements de débâcles significatifs.

Remo Gygax: GPU accelerated numerical simulations and laboratory experiments on viscous avalanches

Remo Gygax
Director: Prof. Y. Podladchikov
Jury: Prof. M. Jaboyedoff, Prof. F. Herman, L. Räss, C. Longchamp

Numerical simulations are an eective tool in natural risk analysis. They are useful to determine the propagation and the runout distance of gravity driven movements such as rock avalanches. A numerical model based on fluid mechanics is proposed to simulate such events. In absence of an accepted mathematical explanation of the interactions inside a rock avalanche bulk, a numerical viscous framework is established. Several studies have shown that the numerical implementation of physical processes of viscous flow produces a good t to actual observations of rock avalanche propagation. The use of a continuum approach enables to implement the equation of motion and the mass balance equation of viscous flow on a fully staggered grid. These equations are solved using a finite difference scheme.

The anticipated numerical results on viscous ow are well documented. Nevertheless, analogue laboratory experiments with glycerine on an incline are conducted to find the dependencies between the major parameters. The fingering of the viscous ow was successfully reproduced, at the same time in the laboratory as well as in the numerical implementation. Nowadays, High Performance Computing hardware is available at reasonable costs. Using parallel GPU computing with the Nvidia C-CUDA programming architecture allows to accelerate the simulation. The difference in performance is compared to the widely used scientific modelling software MATLAB. We obtain a nearly 158 times faster simulation while running the developed code on the parallel High Performance Computing architecture.

Alizée Vioget: Analyse de l’évolution morphostructurale des falaises littorales du Bessin, Basse-Normandie, France

Alizée Vioget
Director: Prof. Michel Jaboyedoff
Co-directors: Prof. Olivier Maquaire
Expert: MSc. Clément Michoud

The coasts’ recession is a major issue for the management of littoral regions. In this context, two coastal areas in “Calvados” and “Pays de Caux”, French Normandy, are studied by the University of Caen for several years.

The studied section of the cliffs of Bessin is about 5 km long and lies between the World War II artillery batteries of Longues-sur-Mer and Arromanches-les-Bains. The site’s lithology is mainly made of two formations: the limestones of Bessin that lie on top of the marls of Port-en-Bessin. On the coastline, the cliff’s height varies between 10 and 75 meters above sea level. The marl formation acts like an aquitard, as it is semi-impermeable. Therefore, more or less important water outflows are observable at the point of contact between the marls and the limestones.

First, the study aimed to create an up to date geomorphological map as well as a kinematic classification of the existing instabilities of the different cliff’s profiles. This part was realized with on site field measurements. Several profiles were observed depending on the type of cliff studied: sinking of limestone panels due to creeping marls at the base, overhang limestone formation, wave-cut notch, detachment, tilt, rotational rockslide, superficial rockslide etc. These several behaviors depend on the cliff’s exposure to the Channel Sea and weathering factors, morphology, presence of pebble beach etc. Thus, the coastline section was classified depending on the different morphological types observed, which influence the stability and erosion rates. Principal morphological types here are: overhang limestone formation near Cape Manvieux and rotational rockslide by creeping marls near le Chaos.

Then, the cliffs’ condition was compared to the diachronic analysis of the shoreline evolution supported by different photographic documents. This part of the study allowed to refine the spatiotemporal occurrence of the different ground movements. However, cliffs’recession evolves in successive leaps and bounds. Thus, results would not be significant unless there are long observation periods. Therefore, the documents used consisted of orthophotos and oblique aerial pictures that cover a period from 1947 to 2012. This step revealed a recession velocity of about 0.06 to 0.30 m/yr.

Finally, a complex rockslide that happened in May 2013 near Cape Manvieux has been investigated. Its kinematic and the mass volume that has moved were determined. For that purpose, a terrestrial LiDAR acquisition of the instability was performed in July 2013. LiDAR data and field observations let think that the current state of the instability was created by multiple events and is a complex mix of creeping marls and toppling of limestone destabilized by a back subvertical discontinuity which is parallel to the coastline.

The site geomorphological study associated with the diachronical analysis gave lots of information regarding the mechanisms shaping the cliffs of Bessin and their evolution. Thus, the section of interest could be cut into several transects having their own mechanisms and erosion rhythm. Hence, the event of May 2013 could be replaced in its context and described as a major magnitude event which displaced about 30’000 m3.

Cindy Vulliez: Apports des méthodes d’imagerie 3D pour la caractérisation et le monitoring du glissement rocheux de Séchilienne (Vallée de la Romanche, Isère, France)

Cindy Vulliez
Director: Prof. Michel Jaboyedoff
Co-directors: Dr. Antonio Abellán, MSc. Antoine Guerin
External Expert: Marie-Aurélie Chanut

The Sechilienne landslide, which is located in the Romanche Valley (France) is mass movements of about 650 m high and 250 m wide, with a potential volume of 3 million cubic meters of material in the active part. The slope, which is mainly composed of micaschist, is characterized by the presence of a NE-SW sub-vertical fracturing system involved in the destabilization of the area. Several investigations are being performed by different research groups on this landslide, including fieldwork investigations, remote sensing, seismic acquisitions, geochemistry, deformation analysis by extensometers, etc. The rock slope has been continuously moving since the eighties decade, with a growing acceleration during the period 2009-2013 followed by a progressive stabilization during the last years.

In this work, we used different 3D techniques in order to monitor the whole rock slide
displacements. First of all, nine different fieldwork campaigns using Terrestrial Laser Scanning were performed during the last six years to obtain high-resolution point clouds (8 cm point spacing) of the rock slope topography. In addition, we used three Helicopter-based Laser Scanning campaigns carried out in between 2011 and 2014 acquired by the Cerema. Finally, more than 600 photos were taken in April 2015 in order to build a photogrammetric model of the area using Structure-from-Motion (SfM) workflow in Agisoft PhotoScan software. All types of data allowed us having a good spatial vision of the evolution of the whole slope. 

A detailed structural analysis was performed from both LiDAR and SfM point clouds using
Coltop3D. Eight joint sets were detected, allowing us to estimate the susceptibility of the slope to three main failure mechanisms: planar sliding, wedge sliding and flexural toppling. Moreover, we carried out the monitoring of the active area by three approaches: comparisons among all the point clouds, tracking of several points in the frontal area, 3D tracking of several homogenous rocky compartments of the rear part using the roto-translation matrix. Large-scale movements (from several dm to more than 10 m) were observed in the active area with a coupling between subsidence and toppling oriented towards the valley. Lateral structures that cut de rear active part also seem to be affected by a clockwise rotation around the topple axis. Once the individual blocks fell during the period 2009-2014, we individualize their volumes and calculated them. We
also determined a frequency-volume relation of events in the slope and estimated the erosion rate of. Finally, we compared the two methods of imaging based on the results obtained.

The acquisition of accurate topographic data taken from LiDAR and SfM has been useful to
characterize the instability, quantifying the displacements and clarifying the failure mechanisms involved in the complex dynamic of the Sechilienne rockslope active part.

Philippe Limousin: De la caractérisation du sol, à l’étude de propagation et des risques induits : Les cas du glissement de Pont Bourquin

Philippe Limousin
Supervisor: Prof. Michel Jaboyedoff
Co-supervisor: Bernard Vayssade

Les risques liés aux dangers naturels sont de plus en plus présents dans le monde mais encore plus particulièrement dans les pays de montagne, du fait de la multitude de dangers par lesquels ils peuvent être touchés notamment les chutes de blocs ou de pierres, les risques d’inondations, les tremblements de terre mais aussi les glissements de terrains. La caractérisation de ces phénomènes est une recherche qui prend de plus en plus d’importance. En effet pour définir les impacts qu’ils induisent sur la population ou la modification de l’environnement, il faut rechercher les zones où ces phénomènes peuvent se déclencher, trouver leur dynamique d’écoulement et leur propagation ainsi que les facteurs influençant ces différents paramètres.

Le thème principal est l’étude du glissement de terrain, de Pont Bourquin. Pour ce faire il a été analysé les caractéristiques du sol par des essais en laboratoire puis la propagation d’une possible coulée et enfin les vulnérabilités pour trouver finalement le risque induit.

La réflexion s’est articulée selon trois axes. Dans un premier temps, une analyse des comportements du sol et de ces caractéristiques. Dans un second temps, la modélisation du glissement de terrain. Pour finir, une étude de risque liée à la zone de glissements située à Pont Bourquin (Commune de Ormont-dessus), dans le canton de Vaud en Suisse, est réalisée.

Christopher Puglia: Multidisciplinary study of two anthropogenic landslides in Sindhupalchok and Ramecchap districts, Central Nepal

Christopher Puglia
Direction: Prof. Michel Jaboyedoff, Dr. Karen Sudmeier-Rieux, Dr. Marc-Henri Derron, MSc. Pierrick Nicolet

The purpose of this thesis is to explore the socio-economic and technical issues linked to landslides management in Sanusiruwari VDC (Sindhupalchock district) and Namadi VDC (Ramechhap district), central Nepal.

In Nepal, hydropower development is in expansion as it is a possibility to largely improve the electricity network. In the study, they aim for Sanusiruwari project is to supply the national grid and for Namadi to provide energy to the whole community. Nevertheless, their construction caused landslides in both sites making necessary to control and stabilize them.

The first part of the study is technical and it is intended to examine the landslides with observations and photogrammetry to have more information about its possible evolution and to find out if the plants’ construction is the only cause. Then, the Vetiver (Vetiveria ziznioides) is used as stabilization measure in both sites which will reveal issues regarding their maintenances and efficiency.

The second part is social and was conducted with interviews, discussion and participatory risk mapping. As the managers and communities are different for both sites, risks management differed, with different approaches, implications, priorities and opinions in slopes stabilization and hydropower matters. Communities’ involvement is important in Namadi because the project want to share knowledge which is not the case for the other project in Sanusiruwari which is a private sector project. In spite of that, issues related notably to the landslide management will turn out similar.

Roya Olyazadeh: Natural hazards and open source development: adoption and application of mobile and Web-GIS technologies in risk management

Roya Olyazadeh
Director: Prof. Michel Jaboyedoff 
Jury:  Dr. Marc-Henri Derron, Dr. Christian Kaiser, Dr. Anne Puissant, Prof. Suren Erkman

Impacts of natural disasters have increased worldwide in the past decades. Risk assessments and analysis have been effectively pursued by research institutions, national and local governments, NGOs and different stakeholders for some time and a wide range of methodologies and technologies are proposed consequently. Nowadays, risk and disaster management including risk reduction mitigation and alternative selections are becoming more useful with World-Wide-Web and Geospatial Technologies. Web-GIS technologies offer a wide range of solutions to map the disasters, damages, analyze data and publish the results on the web. Open-source Web and Mobile GIS tools can help to improve the analysis of data and reduce the time and cost required. Open-source platforms and data have been widely used today because they stay free and facilitate access to data especially significant in developing countries. This research explores the applications and adoptions of Mobile and Web GIS technologies in the field of risk and disaster management. The purpose of this research is: (l)To review different open source web and mobile GIS systems related to Risk and Disaster management; (2) to explore the adoption and application of web and mobile GIS technologies for the collection, analysis, and decision making in disaster management; (3) to manage risk analysis using open data such as OpenStreetMap (OSM); (4) to apply advanced visualization, central database, fast and easy data and information acquisition. This research was carried out in 3 major phases: risk identification, assessment, and evaluation, which includes developing different platforms using open-source Web-GIS technologies such as OpenLayers, Leaflet maps, Cordova, GeoServer, PostgreSQL as the real DBMS (Database Management System) and PostGIS as its plugin for spatial database management. The first study presents a Web-GIS prototype using OSM data to evaluate the rapid impact of naturally produced disasters like an earthquake for the estimation of total damages. For this purpose, expert knowledge such as earthquake intensifies and vulnerability inputs are imported into the system. The second study uses the same methodology as the first platform and is applied in a teaching project (FIP) at University of Lausanne. Its purpose is to discover the relation between an open-source platform/data and students. The third application reviews the implementation and selected results of a secure Mobile map application called ROOMA (Rapid Offline-Online Mapping Application) for the rapid data collection of landslide hazard in Nepal. This prototype assists the quick creation of landslide inventory maps (LIMs) by collecting information on the type, feature, volume, date, and patterns of landslides. This application comprises Leaflet map coupled with satellite images as a base layer, drawing tools, geolocation (using GPS and the Internet), photo mapping and events clustering. The fourth study presents an improved version of ROOMA for Canton Vaud, Switzerland to collect all events and hazards such as landslide, floods, avalanches, and etc. The last platform reviews an implementation of a decision analysis module based on Multi-Criteria Decision Analysis (MCDA) in the platform of a Natural Risk Management Spatial Decision Support System (SDSS) called “RiskChanges”. This platform involves changes in hydro-meteorological risk and delivers tools for indicating the best risk reduction alternative. This module assists the users by importing the essential factors, such as risk and cost-benefit values from other modules. Besides the combination of the multi-criteria analysis and possible future scenarios in group sessions and comparison the results by means of a numerical and graphical view are carried within the system. The results of these different platforms clarify how open- source GIS technologies can be easily adopted on different levels of risk and disaster management such as post-disaster management, teaching, decision support systems and, etc. Moreover, the results present the technical difficulties to adapt these technologies to real-life situations.