NH10.1

In the scholarly field of hazards, adverse impacts of a hazard event are interpreted as the result of interactions among hazard elements, exposure of entities of value, and vulnerability of the exposed entities. The severity of hazard elements is usually communicated as a magnitude or intensity. Such hazard event magnitude or intensity metrics correspond to the expected damages due to a hazard event given an average exposure and vulnerability. These severity metrics can be used to facilitate hazard communication and enhance emergency management. However, hazard event severity metrics for singular hazard types such as the earthquake Richter magnitude and the Saffir-Simpson hurricane wind scale cannot be readily adapted for multi-hazard comparative analyses. The first and foremost challenge to such comparative analyses is a lack of conceptual framework to systemically classify different hazard event severity metrics. In this presentation, we introduce a four-dimensional typology of hazard event severity metrics for hazard research within a multi-hazard context. The four dimensions include the spatial, temporal, applicational, and indicial dimensions. Based on a literature review on 67 existing hazard event magnitude or intensity scales for 21 singular hazard types, we demonstrate that the proposed typology can be applied to classify hazard event severity metrics. We further implement the proposed typology to two newly developed equivalent hazard event severity metrics called the Gardoni Scale and the Murphy Scale to showcase the utility of the proposed typology in facilitating quantification of hazard severity across different hazard event types.

How to cite: Wang, Y. V. and Sebastian, A.: Typology of Hazard Event Severity Metrics for Multi-Hazard Research, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6468, https://doi.org/10.5194/egusphere-egu21-6468, 2021.

In this paper, we discuss the dynamic nature of risk through the lens of multi-hazard relationships and scenarios. Disaster risk is commonly expressed as (Risk = Hazard × Exposure × Vulnerability). This expression does not communicate the extent to which each term (and therefore risk and impact) can change over time, and any relationships between the four variables. To better convey and discuss multi-hazards and dynamic risk, in July and August 2020 we held two virtual workshops (40 and 35 participants) as part of the GCRF Tomorrow’s Cities Research Hub, which has as its focus four cities Istanbul, Kathmandu, Nairobi, and Quito, with a particular emphasis on the urban poor. During the two workshops, participants (including those from academia, NGOs, and the public sector) from each city generated multi-hazard scenarios that can be used to improve the understanding of dynamic risk and we highlighted three main examples of dynamic risk: (1) The hazard term can involve multiple hazards, with relationships between hazards, and the likelihood or magnitude of single natural hazards and multi-hazard scenarios varying over time. (2) Both the exposure and vulnerability components of the risk equation change over time, and can contribute to the triggering, amplification (or reduction) of multi-hazard events. (3) Progression through multi-hazard scenarios can influence or drive changes in both exposure and/or vulnerability terms. These three statements illustrate the dynamic nature of each component of the risk equation and the existence of relationships between each term. Furthermore, they demonstrate how understanding the multi-hazard landscape and potential multi-hazard scenarios can help to enrich understanding of dynamic risk. This understanding of multi-hazard scenarios can be used to consider potential interventions where risk is dynamic.

How to cite: Gill, J., Hussain, E., Malamud, B., and Šakić Trogrlić, R.: Multi-Hazard Scenarios and Dynamic Risk, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11114, https://doi.org/10.5194/egusphere-egu21-11114, 2021.

Whilst the last decade saw huge scientific advances in understanding natural hazard risks, most research and policy still addresses risk from a single-hazard, single-sector, perspective. This presents obstacles for addressing real-world challenges faced by risk managers and other decision-makers. Firstly, multiple hazards can have interrelated effects on risk. How can risk be better managed by considering these interrelated effects? Secondly, disaster risk management (DRM) measures taken to reduce risk from one hazard may increase risk from another hazard. How can we better account for these dynamic feedbacks between risk drivers? Thirdly, these interrelated effects have impacts across sectors. How can we account for these trade-offs and synergies across sectors, regions, and hazards? The aforementioned challenges exist within the context of an increasingly interconnected world, increased pressure for space, and climate change, in which the magnitude and frequency of single and multi-hazards are changing at an unprecedented rate. A paradigm shift is needed to successfully address these kinds of complex questions and challenges.

The vision of the MYRIAD-EU team is to catalyse this paradigm shift required to move towards a multi-risk, multi-sector, systemic approach to risk management. We embark on a research programme that aims to enable policy-makers, decision-makers, and practitioners to develop forward-looking disaster risk management pathways that assess trade-offs and synergies across sectors, hazards, and scales. To do this, we will co-develop a framework for multi-hazard, multi-sector, systemic risk management, and state-of-the-art products and services to operationalise the framework. To test our framework, products and services, we plan to implement them with stakeholders in five Pilots: North Sea, Canary Islands, Scandinavia, Danube, Veneto. In this contribution, we will present the plans and vision for this ambitious research programme and look for links with existing risk multi-risk projects, networks, and activities.

How to cite: Ward, P. and the MYRIAD-EU team: Towards a multi-risk, multi-sector, systemic approach to risk management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11353, https://doi.org/10.5194/egusphere-egu21-11353, 2021.

The forefront of science now is in bridging fields and making connections across different disciplines, challenging our current understanding of the Earth's changes and overall state. Some of the most challenging science questions now have to do with warnings for significant geohazards and Earth-Space systems' response to climate variability affecting adaptation processes, such as geosphere changes due to climate change and resultant strategies. In recent years, the study of pre-earthquake processes has led for example to developing the lithosphere-atmosphere-ionosphere-coupling concept. This in turn provides new information about the Earth's energy balance (Pulinets and Ouzounov, 2011). From space-born NASA and NOAA Earth observation of atmospheric conditions, we have shown the consistent occurrence of radiative emission anomalies in the atmosphere near or over regions of earthquakes, volcanoes, and geothermal fluxes. Our assessment shows that the latent heat released before major earthquakes is larger than the seismic energy released during the quake (Ouzounov et al., 2018). We find that the associated pre-earthquake phenomena for large events may create an additional thermodynamic contribution in the atmosphere and impact on climate, caused by sources of Earth de-gassing in the lithosphere and followed by ionization processes. Because of these findings, we start exploring major global geodynamics activities and their impact on atmospheric processes and climate through the geosphere coupling channels as a potential forward process of interaction between geohazards and climate adaptation. The reverse mechanism of climate adaptation's impact on geohazards is based on the initial idea that climate adaptation could force additional geohazards activities (McGuire, 2010). The removal of ice sheets may somehow or likely have permitted the release of stresses that had accumulated on previously confined faults, triggering earthquakes in the US, Canada, and Europe. How realistically is it to expect a change in the existing earthquake patterns in Europe, the USA, and Canada during climate change processes? It is plausible, but we do not yet know the answer. Our goal is to explore the coupling between geohazards processes and climate change processes through the lithosphere-atmosphere framework, focusing on dynamic environments, exhibiting a change in physical and thermodynamics processes over relatively small-time scales.

How to cite: Ouzounov, D., Kafatos, M., and Taylor, P.: Geohazard and Climate adaption:  impacts and interconnectivity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16297, https://doi.org/10.5194/egusphere-egu21-16297, 2021.

Humanitarian crises often result from a combination of multiple physical and societal processes, rather than independently from a single driver. The combination of processes leads to “compound events”, whose socio-economic impacts could be larger than those expected by analysing each driver individually. In recent years, the Horn of Africa has been increasingly exposed to compound events. Frequent extreme wet and dry conditions often compound with its fragile context characterized by internal ethnic conflicts, unstable governments, and high levels of poverty, resulting in impacts usually larger than anticipated. An improved understanding of the drivers and their interactions can help to reduce future risks associated with compound events.

Here, we conducted a retrospective analysis of the humanitarian crises that occurred in Kenya and Ethiopia in 2017-2018. In this period, a severe drought that occurred over the span of around 18/24 months, was followed by extensive flooding during the 2018 March-May rainy season. The impacts and their related drivers were explored, first through a review of the literature, and then through a survey and semi-structured interviews with several stakeholders from national agencies, civil societies, and NGOs. The approach resulted in a participatory co-creation of causal loop diagrams used as qualitative mental maps of the perceived drivers and interactions. These were then used as a basis for the semi-quantitative analysis of driver-interactions, modelling the impacts of immediate and long-term effects of the compound events.

The analysis disentangles the spatial-temporal feedback of drought and flood events, and their interconnections with societal forces. We found both negative and positive feedback on the food security level of the Kenyan and Ethiopian population. For instance, the flood initially exacerbated food insecurity caused by the long drought, but in the long term, it helped alleviate related water shortages. The results show the importance of taking drought response actions that first do not increase the risk related to subsequent floods (e.g., encouraging the allocation of people in lowland areas), but also that can boost the positive impacts of above-average rainfall on drought effects. Moreover, we investigated potential early warning signs and explored the impacts of several measures, identifying windows of opportunity for interventions.

How to cite: Matano, A., Van Loon, A., de Ruiter, M., Koehler, J., de Moel, H., and Ward, P.: Compound Drought-Flood Events in Fragile Contexts: Examples from the Horn of Africa, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10148, https://doi.org/10.5194/egusphere-egu21-10148, 2021.

The EU Disaster Risk Management Knowledge Centre (DRMKC)[1] is currently developing a WebGIS-based platform – the Risk Data Hub[2] - aimed at improving access to and sharing of EU-wide risk data, tools, and methodologies in support to policy Directorate-General and national authorities for their Disaster Risk Management. The development of the platform is based on the results of a ‘’Needs and Gaps” analysis performed as part of the preparation of the European Commission Staff Working Document – ‘’Overview of Natural and Man-made Disaster Risks the European Union may face’’ (2014^[3], 2017^[4],2020^[5]).  The overview concerned the 31 summaries of the National Risk Assessment (NRA) submitted to the European Commission by the Participant States of the Union of Civil Protection Mechanism.  For multi-hazard assessments, it concluded that a gap exists between the knowledge and data available in the scientific community and the accessibility and usability by Decision Makers and the Civil Protection community. With the DRMKC’s Risk Data Hub development, we support the integration of multi-hazard risk assessment and mapping into evidence-based decision-making, risk-reduction strategies, and adaptation plans.

Based on this context and utilizing spatial analysis of exposed elements to various hazards across Europe, we present in this study a novel methodological approach for the assessment of multi-hazard potential impact. This methodology is currently implemented on the DRMKC Risk Data Hub WebGIS platform. The methodological approach is based on a hotspot analysis applied to residential area and population exposed to single hazards such as river flood, coastal inundation, earthquakes, landslides, forest fire, and subsidence. Based on different aggregations of the exposure we identify the statistically significant hotspot for the considered hazard exposure. Using Stouffer’s method (Stouffer et al., 1949) for meta-analysis, the statistically significant exposure hotspots for single hazards are combined and subsequently, spatial extension and location of multi-hazards potential impact can be identified.  Consequently, we provide the spatial overview of regions expected to suffer significant multi-hazard potential impacts across Europe at the subnational level. Based on theoretical aspects developed in the literature, we put forward a multi-hazard interaction framework for the sub-national spatial extent across Europe. Finally, a validation of the results against the multi-hazard disaster loss data hosted on the DRMKC Risk Data Hub will be exercised.

The outcome of this study will provide valuable input for the Disaster Risk Management policy support and will assist national authorities on the implementation of a multi-hazard approach in the National Risk Assessments preparation.

How to cite: Antofie, T.-E., Luoni, S., Marin-Ferrer, M., Patrascu, F., Eklund, G., Lindl, F., Santini, M., and Brian, D.: Identifying multi-hazard potential impact at the pan-European level: the DRMKC Risk Data Hub methodology, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12061, https://doi.org/10.5194/egusphere-egu21-12061, 2021.

Methodologies to assess risk from multiple hazards are increasingly being developed, and a growing body of literature reports implementations of multi-hazard risk assessments. However, fewer studies so far have attempted to complement a multiple hazard perspective with an equally sophisticated approach to assess the other subcomponents of risk, notably multi-vulnerability, in order to represent not just multi-hazard but rather multi-risk dynamics.

Using the impact chains approach, we have developed a participatory multi-risk assessment of the Marrakech-Safi region (Morocco). Floods and droughts, two of the most relevant hazards affecting the region, were considered for the study, with the aim of capturing their effects on diverse elements at risk, such as human security and rural livelihoods.

First, in order to identify the drivers of the most relevant impact-related risks associated with floods and droughts in the region, a set of four impact chains were co-developed with local experts and regional stakeholders during a dedicated workshop. Thereby, each type of risk was narrowly defined (i.e. “ risk of physical harm for the population due to floods”, “risk from loss of infrastructures and properties due to floods”, “risk of economic losses for rainfed agricultural systems due to drought”, “risk of economic losses for irrigated agricultural systems due to drought”), and the principal cause-effect connections between drivers were identified.

As a second step, each impact chain informed the spatial analysis of both single and multi-risk based on secondary data at the municipal level (n = 255 municipalities). The Standardized Precipitation Index (SPI) was used to characterize drought hazard for rainfed (SPI3) and irrigated (SPI12) farmlands, whereas a hydrological model was developed to simulate a 100-year return period flood. Exposure of people to floods was assessed using the WorldPop population distribution dataset, while a regional land use-land cover model was developed to assess exposure of irrigated and rainfed farmlands to drought. For each type of risk, weighted vulnerability indices were computed based on a set of social and environmental indicators, and combined to the hazard exposure assessments via a matrix approach to obtain single-risk classes. Ultimately, the four single-risk exposure and vulnerability scores were combined into a multi-exposure and multi-vulnerability score respectively, which were then used to obtain the final multi-risk classes.

Results show that the vast majority of municipalities in the region are affected by two risks or more, and that multi-vulnerability classes influenced importantly the final multi-risk assessment. The methodology allowed a complex representation of single- and multi-risk, integrating qualitative and quantitative outputs: impact chains proved to be useful at representing the inherent complexities of risk, while the spatial analysis helped to understand regional differences in multi-risk in all components of hazard, exposure and vulnerability. The results of the assessments are expected to support multi-sectoral planning at the regional level. However, further research is needed to understand how to manage the increase in complexity should more hazard and/or more risk typologies be considered, and how to best model the complex interactions emerging from the impact chains in a more dynamic way.

How to cite: Cotti, D., Harb, M., Hadri, A., Trasforini, E., Libertino, A., Rkha Chaham, K., Bellert, F., and Hagenlocher, M.: Assessing multi-risk through impact chains and spatial analysis: experience from the Marrakech-Safi region (Morocco), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12514, https://doi.org/10.5194/egusphere-egu21-12514, 2021.

Uganda is regularly affected by multiple natural hazards, including floods, droughts, earthquakes, landslides and windstorms. This is due to a combination of natural biophysical factors such as steep topography, intense rainfall, variability of dry and rain seasons and high weathering rates. In addition, high population density, deforestation and other human-induced land use changes, and high poverty levels are believed to have an influence on the patterns of natural hazards and their impacts in the region. Despite this, there are limited studies that assess where and when natural hazards occur in Uganda, and a dearth of information on the processes involved. In addition, drivers and earth/landscape characteristics controlling the occurrence of natural hazards in the country remain poorly understood despite the high need for effective disaster risk reduction. Here, we present the ongoing methodological research framework and the first results of a study whose main objective is to understand the spatial and temporal occurrence of natural hazards that affect the Kigezi Highlands of south western Uganda and their interactions. To this end, the study is undertaking a comprehensive regional hazard inventory consisting of satellite image analysis, field surveys and exploration of literature and archives. Historical aerial photos and interviews with the elderly are important tools to analyze the impact of multi-decadal human-induced land use changes on natural hazard occurrences. Meanwhile, a network of 15 geo-observers, i.e. citizens of local communities distributed across representative landscapes of the study area, was established in December 2019. Trained at using smartphone technology, they collect information (processes and impacts) on seven different natural hazards (droughts, earthquakes, floods, hailstorms, landslides, lightning, and windstorms) whenever they occur.  During the first 12 months, 204 natural hazard events with accurate timing information have been reported by the geo-observers. Combined to field survey, these recent events have been associated mainly with the occurrence of > 3000 shallow landslides and 30 floods, frequently in co-occurrence and triggered by heavy rainfall. Additional inventory from Google Earth and Planet imagery covering a region much larger than that of the geo-observer network and a time window of more than 10 years shows an extra 230 landslide and flood occurrences, while archives and literature indicate 226 natural hazard events over the last 30 years. The preliminary results already demonstrate the value of citizen-science in producing highly detailed natural hazard inventory. A combination of different inventory methods improves the level of accuracy in understanding the spatial-temporal distribution of natural hazards.

How to cite: Kanyiginya, V., Twongyirwe, R., Kagoro, G., Mubiru, D., Kervyn, M., and Dewitte, O.: Inventory and preliminary assessment of natural hazards in Kigezi highlands, South Western Uganda, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12974, https://doi.org/10.5194/egusphere-egu21-12974, 2021.

Global policy frameworks, such as the Sendai Framework for Disaster Risk Reduction 2015-2030, increasingly advocate for multi-hazard approaches across different spatial scales. However, management approaches on the ground are still informed by siloed approaches based on one single natural hazard (e.g. flood, earthquake, snowstorm). However, locations are rarely subjected to a single natural hazard but rather prone to more than one. These different hazards and their interactions (e.g. one natural hazard triggering or increasing the probability of one or more natural hazards), together with exposure and vulnerability, shape the disaster landscape of a given region and associated disaster impact.  Here, as part of the UK GCRF funded research grant “Tomorrow’s Cities” we first map out the single natural hazardscape for Nairobi using evidence collected through peer-reviewed literature, grey literature, social media and newspapers. We find the following hazard groups and hazard types present in Nairobi: (i) geophysical (earthquakes, volcanic eruptions, landslides), (ii) hydrological (floods and droughts), (iii) shallow earth processes (regional subsidence, ground collapse, soil subsidence, ground heave), (iv) atmospheric hazards (storm, hail, lightning, extreme heat, extreme cold), (v) biophysical (urban fires), and vi) space hazards (geomatic storms, and impact events). The breadth of single natural hazards that can potentially impact Nairobi is much larger than normally considered by individual hazard managers that work in Nairobi. We then use a global hazard matrix to identify possible hazard interactions, focusing on the following interaction mechanisms: (i) hazard triggering secondary hazard, (ii) hazards amplifying the possibility of the secondary hazard occurring.  We identify 67 possible interactions, as well as some of the interaction cascade typologies that are typical for Nairobi (e.g. a storm triggers and increases the probability of a flood which in turn increases the probability of a flood). Our results indicate a breadth of natural hazards and their interactions in Nairobi, and emphasise a need for a multi-hazard approach to disaster risk reduction.

How to cite: Malamud, B. D., Mwangi, E., Gill, J., Hussain, E., Taylor, F., and Sakic Trogrlic, R.: Multiple-hazards and their interactions in urban low-to-middle income countries: a case study from Nairobi, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16053, https://doi.org/10.5194/egusphere-egu21-16053, 2021.

Nepal, a mountainous country, is experiencing multiple disasters, majority of which are induced by Climate Change. Erratic rainfall, extremely high temperature during summer, cold waves are some of them. Nepal will experience the impacts of climate change through an increase in temperature, more frequent heat waves and shorter frost durations in the future (5AR IPCC). Nepal is witnessing the increased maximum temperature of 0.56^oC per decade and the increment of the temperature is even higher in the mountain region (ICIMOD 2019). One of the major impacts of Climate Change among others, is glacier retreat and Glacial Lake Outburst Floods (GLOFS). Nepal has already experienced more than 26 GLOFS (UNDP and ICIMOD 2020), originated both from Nepal and China, Tibet.

The Imja Glacial Lake is located at 27° 53′ 55“ N latitude, 86° 55’ 20” E longitude and at an altitude of 5010 m in Everest Region of Nepal Himalayas.  Imja was identified during 1960s as a small supra lake, was later expanded to an area of 1.28 Km², 148.9 meter deep, holding 75.2 million cubic meters of water in 2014.   Lake lowering by 3.4 metres and establishment of early warning system was done in 2016 by the Government of Nepal and UNDP with the support of Global Environment Facility.  Hydro-met stations & GLOF Sensors in the periphery and downstream  of Imja Lake and automated early warning sirens in six prime settlements in the  downstream of Imja  watershed  linking with  dynamic SMS Alert system along 50 km downstream of Imja Dudh Koshi River have been have been linked with community-based DRM institutions at local government level. This initiative is important for preparedness and response of GLOF Risk Reduction in the Imja Valley, benefitting 71,752 vulnerable people, both local and the tourists visiting the Everest Region of Nepal.

Early Warning System of Tsho Rolpa Glacial Lake, the biggest Glacial Lake of Nepal is another example in the such system. New inventory of Glacial Lakes has identified 47 critical lakes as priority lakes for GLOF Risk Reduction in Koshi, Gandaki and Karnali basins. In the new context of federal  governance system, the role of federal, province and local government and communities is crucial  for achieving the targets of  Sendai Framework for Disaster Risk Reduction , particularly target “g” and SDGs 11 and 13  through integrating  the targets in the regular planning and   its’ implementation for resilient and Sustainable Development of  Nepal.

References:

Glacial lakes and glacial lake outburst floods in Nepal. Kathmandu, ICIMOD 2011,  Nepal Disaster Report, Ministry of Home affairs (MoHA) , 2015, 2018 Annual Reports UNDP 2016, 2017 and 2018,  Imja Hydro-Meteorological and Early Warning System User Manual, Government of Nepal and UNDP, 2017 Project Completion Report: Community Based Flood and Glacial Lake Outburst Risk Reduction Project, Government of Nepal and UNDP, 2017,  Inventory of glacial lakes and identification of potentially dangerous glacial lakes in the Koshi, Gandaki, and Karnali River Basins of Nepal, the Tibet Autonomous Region of China, and India. Research Report, ICIMOD and UNDP, 2020

How to cite: Kc, D., Khatri, T., and Sharma, R.: Glacial Lake Outburst Floods Early Warning System to save lives and livelihood of the Nepal Himalaya communities: A case Study of Imja Glacial Lake, Nepal, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4163, https://doi.org/10.5194/egusphere-egu21-4163, 2021.

Istanbul is a major global urban centre. With city expansion expected to continue over the next few decades there is a real opportunity for urban growth that incorporates disaster risk reduction (DRR). But in order to develop DRR inclusive urban development strategies we need to understand the breadth of hazards that can affect the city and their potential interactions.

To create a single hazard overview for the city we searched through peer-reviewed literature, reports, government websites and international disaster databases for hazard occurrences. Of the 34 natural hazards in our global hazard table encompassing five major hazard groups (geophysical, shallow process, meteorological, hydrological, climatological and extraterrestrial), we found 27 of these had occurred or had the potential to occur in Istanbul. Notable absences were snow avalanches, glacial outburst floods and direct volcanic hazards. However, ash dispersal models show that ash from volcanic eruptions in the Mediterranean can affect the city.

Additionally, we present an interaction matrix for hazards relevant to the city that shows how one hazard may trigger or increase the probability of another. We adapted the global hazard interaction matrix of Gill and Malamud (2014) by removing hazards that were not relevant to Istanbul and supplementing it with specific examples that have occurred in the city. We found 85 such interactions that reveal the potential for interacting chains of natural hazards.

We discuss how multi-hazard scenarios, developed through expert stakeholder engagement and based on the hazard interaction matrix, are an effective way to explore and communicate the dynamic variability of exposure, vulnerability and therefore, multi-hazard risk.

How to cite: Hussain, E., Cakti, E., Yolcu, A., Malamud, B., Gill, J., and Trogrlic, R.: Tomorrow’s Cities: Multi-hazard interactions to inform disaster risk reduction in Istanbul, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13075, https://doi.org/10.5194/egusphere-egu21-13075, 2021.