NH9.9

EDI

UN projects urban agglomeration to increase to 68% by 2050 from 55%. The majority of this positive trend is projected to happen in developing countries like those in the tropics (24S—24N). Especially in urban centres, the increasing population is motivated to consider alternative locations to settle. Hence, urban areas at the coast and mountainous terrains expand towards hillslopes and flood plains, increasing the exposure to natural hazards, especially landslides and floods. Heat extremes are increasing in frequency and severity in a warming climate, and the transformation of the land surface in urban centres (heat-absorbing materials, such as asphalt, steel, and brick) causes temperatures to rise further. Understanding the chance of heat extremes and their impacts is vital to allow society to adapt to future risks. Rapid agglomeration also fosters informal housing in those peri-urban areas. Those informal structures are not only structurally more vulnerable, but they also partly increase the impact of some natural hazards by, for instance, poorly regulated water management systems. The session is dedicated to contributions with national, regional, and local perspectives on urban interaction with natural hazards. The session aims to bring together experts from both science and practice to offer a platform to raise awareness and explore solutions. We seek to discuss the following topics, among others, during the session:
- Expected changes in exposure and vulnerability to natural hazards due to urbanization
- Whether informal housing alter natural hazard susceptibility
- Impacts of natural hazards as a result of increasing concentration of population in specific regions
- The role of climate change on natural hazards in urban spaces
- Impacts of heat extremes on human health and society

Convener: Ugur Ozturk | Co-conveners: Vikki Thompson, Elisa Bozzolan, Chloe BrimicombeECSECS, Viktor RözerECSECS, Eunice LoECSECS, Ana Maria Vicedo Cabrera, Scira Menoni
Presentations
| Mon, 23 May, 08:30–11:50 (CEST)
 
Room 1.31/32

Presentations: Mon, 23 May | Room 1.31/32

Chairpersons: Ugur Ozturk, Elisa Bozzolan, Viktor Rözer
08:30–08:35
08:35–08:45
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EGU22-10366
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solicited
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Virtual presentation
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Bruce D. Malamud, Robert Šakić Trogrlić, Ekbal Hussain, Harriet Thompson, Emin Yahya Menteşe, Emine Öner, Aslıhan Yolcu, Emmah Mwangi, and Joel Gill

Single natural hazards, multi-hazards, and anthropogenic processes all contribute to dynamic risk due to the changing nature of the hazard, exposure, and vulnerability over time. Here we discuss the development of dynamic risk scenarios for single and multi-hazards, including multi-hazard interrelationships, in the context of three urban areas, Istanbul, Kathmandu, and Nairobi, all foci of the UK GCRF funded “Tomorrow’s Cities” Research Hub. We first do systematic overviews of multiple sources of evidence (academic and grey literature, online media, social media) to produce a profile of single hazards and multi-hazard interrelationships for each urban area, from which we produce dynamic risk scenarios. Then, we further developed dynamic risk scenarios through co-production with relevant local hazard stakeholders in facilitated workshops and semi-structured interviews in Nairobi and Istanbul. The dynamic risk scenarios include multiple types of single hazards, three different hazard interrelationships (i.e., triggering, increased probability, and compound hazards) and anthropogenic processes. These dynamic risk scenarios are relevant for short-term considerations (e.g., days or weeks, such as an earthquake triggering landslides and blocking rivers) or longer-term (such as climate change influencing the hazard, or anthropogenic processes of urban growth influence the hazard, exposure, and vulnerability). Examples of challenges identified by stakeholders include governance-related issues, such as siloed approaches to hazards which are often single-hazard focused, lack of enforcement of regulations, translation of planning to implementation, centralised policy-making, needs beyond electoral cycles, lack of financial and human resources, and disconnect between scientific and policy-making communities. Other challenges stakeholders identified include a lack of existing data and research in their region on multi-hazard interrelationships, anthropogenic processes and risk, and other components that make up dynamic risk scenarios. Opportunities identified by stakeholders include increased awareness of the factors that might influence risk dynamically in their urban region and integration of these factors into existing urban regeneration project planning. As identified by local stakeholders, these scenarios have a vast array of potential benefits for disaster risk management in their cities, especially in terms of enhanced preparedness and risk-informed planning.

How to cite: Malamud, B. D., Šakić Trogrlić, R., Hussain, E., Thompson, H., Yahya Menteşe, E., Öner, E., Yolcu, A., Mwangi, E., and Gill, J.: Dynamic risk scenarios for single and multi-hazards in the Global South: Nairobi, Istanbul and Kathmandu, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10366, https://doi.org/10.5194/egusphere-egu22-10366, 2022.

08:45–08:52
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EGU22-12947
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Presentation form not yet defined
Piero Campalani, Massimiliano Pittore, and Kathrin Renner

A consistent and comprehensive understanding of risk related to multiple natural hazards threatening population, property and infrastructure is a pillar of the Sendai Framework for Disaster Risk Reduction, and lays at the base of most risk mitigation initiatives. This is particularly challenging since the relevant hazards (e.g., earthquakes, floods or landslides) are often different in terms of recurrence periods, spatial footprint and intensity. Also, the analysis and assessment of risk is based in turn on the knowledge of factors other from hazard, namely exposure and vulnerability. Exposure refers to the communities, assets and systems that are exposed to the hazards and susceptible to damage. This information should be available at the spatial scale and resolution that is most suitable to the considered hazards, and be up-to-date (or reasonably recent to ensure representativeness). Exposure is also tightly connected to the chosen vulnerability modelling approach, hence proving a critical component in the risk assessment pipeline to grant reliable estimates. While gathering a satisfactory exposure dataset from authoritative sources is usually difficult, the task might prove unfeasible in many economically developing countries, where the sheer amount of technical and economical resources needed to collect and maintain such information (e.g., population and housing census, transportation infrastructure, etc.) might exceed the capacity of the local institutions, especially in countries undergoing rapid changes due to urbanization processes. In the last decade, fortunately, several international and global projects made available a significant wealth of data, free of cost and often at regional and global scale. This has proven invaluable to carry out small- and large-scale risk assessment with unprecedented resolution and geographical coverage. However, often the specific characteristics of these datasets and their inherent limitations are not easy to be taken into consideration, therefore paving the way to unwanted biases in the resulting estimates.  

In our contribution we will report on the activities carried out to develop exposure information for multi-hazard risk assessment in Burundi, focusing on the integration of multiple information sources for population distribution and road infrastructure, and on their use in probabilistic landslides risk assessment. The limitations and perspectives of the use of open data and tools will be presented and discussed, along with the role of transparent and reproducible research in using, updating and sharing such data.  

The described research activities have been carried out within the framework of an international project funded by the International Organization of Migration (IOM) and coordinated by IDOM (Spain).

How to cite: Campalani, P., Pittore, M., and Renner, K.: The role of open exposure data and reproducible research for large-area multi-hazard risk applications in economically developing countries. The case study of Burundi, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12947, https://doi.org/10.5194/egusphere-egu22-12947, 2022.

Floods & Rainfalls
08:52–08:59
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EGU22-8091
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ECS
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Presentation form not yet defined
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Jean Nsabimana, Sabine Henry, Aloys Ndayisenga, Désiré Kubwimana, Olivier Dewitte, François Kervyn de Meerendré, and Caroline Michellier

Disasters related to hydrological hazards are frequent, occur worldwide, and regularly devastate many African cities. The victims are commonly among the population in precarious situations, without solid infrastructure and with incomes too low to recover from disasters.

Located in the western branch of the East African Rift, and squeezed between the shore of Lake Tanganyika and steep hillslopes, the city of Bujumbura hosts approximately 800,000 people. It is regularly affected by disasters related to lake and river floods, flash floods, riverbank collapses, and gullies. This research aims to assess people's vulnerability to these hydrological processes through the analysis of the territorial vulnerability of the city. To achieve this objective, we present here the first step which focuses on the evaluation of the exposure to past hydrological disasters.

We built a comprehensive dataset using information from different sources, such the Civil Protection, that we combined and complemented with field data collection obtained from qualitative and quantitative surveys. Given the limited information on the susceptibility to the various processes studied, the distribution of past disasters is used as an indicator of the exposure of different parts of the city to hydrological hazards. This phenomenological approach is a key step to map and understand risk due to hydrological hazards.

Between 1990 and 2021, the city recorded more than 210 catastrophic events. Flooding was the most frequent hazard. For example, with a rise of more than 2m above its normal level, the Lake Tanganyika flooding in April 2021 has induced the displacement of many people and the abandonment of many houses and recreation centers. Flash flooding and gullying have been reported mostly at the foot of the hillslopes. The collapse of river banks has also caused severe damages to infrastructures, along the major rivers crossing the city.

Like many African cities, Bujumbura is characterized by the non-compliance with the law, an inefficient drainage system, the anthropization of the hillslopes overlooking the city, the increasing demand for housing and a lack of structure in its urban expansion. The older neighborhoods of central Bujumbura seem adapted to cope with these types of events, while the peri-urban areas are not. The combination of these vulnerability factors makes Bujumbura more exposed to disasters of hydrological origin.

How to cite: Nsabimana, J., Henry, S., Ndayisenga, A., Kubwimana, D., Dewitte, O., Kervyn de Meerendré, F., and Michellier, C.: Exposure to past disasters related to hydrological hazards: the case of Bujumbura city, Burundi, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8091, https://doi.org/10.5194/egusphere-egu22-8091, 2022.

08:59–09:06
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EGU22-3600
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Highlight
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Presentation form not yet defined
Frédéric Grelot

Following the example of pioneering countries (UK, USA in particular), since 2010, in France, local managers have been required to justify the efficiency of hydraulic infrastructure projects (dyke, dam, etc.) for flood prevention in order to claim subsidies granted by the State. The efficiency assessment must be carried out according to a cost-benefit analysis (CBA) respecting the State's recommendations. Among these recommendations, it is required to estimate the impact of the project on the monetised damage of floods (difference in mean annualised damage between the reference situation and the situation with the project). This recommendation has led to many advances in French flood damage modelling practice. 

The French government also requires that a so-called "constant land use" assumption be made. In concrete terms, this means estimating damage by considering that the land use remains "frozen" in the state it is in at the time of the study. This assumption greatly facilitates the implementation of the method, as it makes it unnecessary to make projections on the evolution of land use, either in the reference situation or in the project situation. The main reason for this recommendation is not that, but that the State considers that anticipating changes in land use as a result of the project would be contrary to the policy of regulating land use in flood-prone areas that it has been pursuing since the early 1980s. At the same time, the French government is pursuing a policy to encourage territories not to rely entirely on hydraulic infrastructures, by promoting so-called integrated flood management projects (combining crisis management, control of land use and adaptation of existing stakes). In practice, the "constant land use" assumption is not verified, even less so on the time scale of the economic evaluation. It is very common that the installation of a hydraulic infrastructure is associated with an intensification of urbanisation in the newly protected area, less so with a disuse of the area.

The objective of our work is to show how relaxing the "constant land use" assumption in the economic evaluation based on the estimation of flood damages can, contrary to the fears expressed by the French State, allow to better clarify the irrelevance of focusing exclusively on structural solutions, without questioning the interest of controlling the use of flood-prone areas. To this end, we show how to relax this assumption in practice within the framework of a CBA. Then, based on a database of about 200 CBAs carried out to obtain subsidies over the last 10 years, we analyse the influence of the "constant land use" assumption on the estimation of the efficiency of projects.

In perspective, we argue that relaxing this assumption could also allow to enter a virtuous circle of knowledge production by encouraging the consolidation of the understanding of the co-evolution of urbanisation and hydraulic infrastructures.

How to cite: Grelot, F.: Urbanisation in flood-prone areas, hydraulic infrastructures and economic evaluation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3600, https://doi.org/10.5194/egusphere-egu22-3600, 2022.

09:06–09:13
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EGU22-6223
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ECS
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On-site presentation
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Josué Mugisho Bachinyaga, Axel Deijns, Guy Ilombe Mawe, François Kervyn, Caroline Michellier, Toussaint Mugaruka Bibentyo, Jaziel Nkere Buliba, Charles Nzolang, Benoît Smets, and Olivier Dewitte

Uvira is a rapidly growing city of about 600,000 inhabitants in DR Congo. Squeezed between the shore of Lake Tanganyika and steep mountains hillslopes, and under the influence of a tropical climate, the city is familiar with flash floods. Nevertheless, the impacts of the flash flood event of April 2020 have been unprecedented in the last decades. Debris-rich flash floods led to at least 43 deaths, nearly 200 injuries, more than 5,500 houses destroyed and at least 70,000 people made homeless. Dozens of socio-economic infrastructures were damaged and nearly 280,000 people were left without hydroelectric power as a result of damage to water and electricity distribution networks in the city. In this work we explore the natural and anthropogenic causes of the exceptional impacts of these flash floods. To do so, we use satellite images, historical aerial photographs, social media reports, field observations, and details provided by local stakeholders and citizen observers. We show that a high-magnitude rainfall event, that occurred at the end of a wetter-than-usual rainy season, triggered, over an exceptionally large area for the region, hundreds of landslides in the upper parts of the watersheds. These landsides transported extra material to the flooded rivers, increasing their sediment content and lateral mobility. We also show that the landscapes of the watersheds where this compound event occurred remained rural in the last six decades and were not impacted by significant forest cover changes and road construction, hence eluding the role of key potential human activities on the magnitude of the flash floods. However, downstream, the city expanded with little consideration of the geomorphological context of the environment where the alluvial fans and flood plains of the rivers have been significantly urbanized in the last decades, often in an informal manner. The impacts of the April 2020 flash flood event are still present almost after two years  and are anticipated to remain at least a few more years; most remarkably, the disturbance of the river dynamics and the severe bank erosion caused by the large supply of sediment. Furthermore, often-uncontrolled sediment mining, seen here by the local people as an opportunity, exacerbates the unpredictable dynamics of the system. In the meantime, flooded areas where houses were destroyed are being resettled. Although authorities and inhabitants are aware of the danger, they face limited means to improve the management and planning of the city.

How to cite: Mugisho Bachinyaga, J., Deijns, A., Ilombe Mawe, G., Kervyn, F., Michellier, C., Mugaruka Bibentyo, T., Nkere Buliba, J., Nzolang, C., Smets, B., and Dewitte, O.: The flash floods of April 2020 in Uvira (DR Congo): story of an event with extreme impacts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6223, https://doi.org/10.5194/egusphere-egu22-6223, 2022.

09:13–09:20
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EGU22-7111
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Virtual presentation
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Martin Brook, Matt Cook, and Murry Cave

Landslides are widespread natural hazards that are responsible for substantial economic and societal damage globally each year. In New Zealand, landslides frequently occur on soil and rock, often triggered by high rainfall and/or seismic activity. This study focuses on the Gisborne district on New Zealand’s North Island. The area is particularly susceptible to landslide hazards due to (1) the region's location on an active plate boundary, (2) steep slopes, (3) relatively young, soft geology, (4) land use change, and (5) extreme rainfall events including landfall of extra-tropical cyclones. The interplay of several of these factors led to a particularly damaging rainfall-induced landsliding event after 4th November 2021, following >200 mm of rain falling in parts of the district over 24 hours. Effects across the region were widespread. Damage to, and evacuation of, residential properties occurred in Gisborne city itself, from shallow rotational slumping and earthflows. The vulnerability of the city’s water supply (via the Te Arai Pipeline) was highlighted by the reactivation of a large complex landslide, that extended to within a few meters of the pipeline. Destruction of the (mothballed) Gisborne-Wairoa railway line occurred near Beach Loop due to reactivation of the Whareongaonga Landslide. Across the Gisborne district, detecting ground deformation related to landslides is vital for identifying and managing areas at risk. Interferometric synthetic aperture radar (InSAR) revealed that many of the landslides that occurred following the November 2021 rainfall event were on slopes that had been actively deforming for several years. Thus, in future, InSAR should prove useful for detecting, mapping and monitoring landslides in the district, and assisting with planning decision-making.

How to cite: Brook, M., Cook, M., and Cave, M.: Infrastructure-damaging landslides from an extreme rainfall event: case study from Gisborne, New Zealand, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7111, https://doi.org/10.5194/egusphere-egu22-7111, 2022.

Landslides
09:20–09:27
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EGU22-5247
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On-site presentation
William Frodella, Ascanio Rosi, Daniele Spizzichino, Massimiliano Nocentini, Luca Lombardi, Pietro Vannocci, Claudio Margottini, Veronica Tofani, and Nicola Casagli

The High City of Antananarivo is one of the most important built cultural heritage sites of Madagascar, and therefore is part of the UNESCO Tentative List. Built on the hilltop of a granite ridge elevating above the Ikopa river valley, it’s renowned for its baroque-style palaces the Rova royal complex and gothic cathedrals dating back to the XIX century. During the winter of 2015, the twin cyclones Bansi and Chedza hit the urban area of Antananarivo, triggering floods and several shallow landslides, which caused thousands of evacuees and many casualties. Between 2018 and 2019 several rockfalls occurred from the rock cliffs of the Analamanga hills destroying housings and killing over 30 people. Both events showed that landslides can pose a high risk to the safety of the inhabitants, the infrastructures, and the cultural heritage of the High City of Antananarivo. To assess landslide hazard an integrated approach was adopted by means of the following actions: i) creation of a multitemporal slope-scale landslide inventory; ii) geotechnical characterization of the involved materials; iii) analysis of shallow landslide susceptibility; iv) runout analysis of debris flows channeling within large creek gullies; v) landslide kinematic analysis of the rockmass; vi) simulation of rockfall trajectories; vii) analysis of rainfall data. The results show that the main factors affecting landslides are slope, lithology, creek-gully erosion and anthropization, while most of the landslide events are clearly triggered by heavy rainfall events. The landslide-prone areas (including shallow landslides, rock falls and debris flows) are located primarily along the cliff bounding the western hill slope, the southeastern sector, where abandoned quarries form large slope cuts, and subordinately in the steep creek catchment just east of the Rova. The produced thematic maps represent fundamental land use management tools to be used as a first step towards a geo-hydrological risk reduction strategy by the institutions and actors involved in the High City protection and conservation. The conducted study represents an important contribution for improving the knowledge on landslides processes in an area with limited data such as Madagascar and Antananarivo in particular, and may be reproduced in cultural heritage sites characterized by similar geomorphological and urban scenarios.

How to cite: Frodella, W., Rosi, A., Spizzichino, D., Nocentini, M., Lombardi, L., Vannocci, P., Margottini, C., Tofani, V., and Casagli, N.: Assessing landslide hazard in the High City of Antananarivo (Madagascar), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5247, https://doi.org/10.5194/egusphere-egu22-5247, 2022.

09:27–09:34
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EGU22-1661
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Virtual presentation
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John F. Dehls and Rajinder K. Bhasin

The Himalayan State of Sikkim is prone to some of the world's largest landslides which have caused catastrophic damages to lives, properties and infrastructures in the region. The state capital, Gangtok, has experienced rapid population growth over the last decades. The rate of urban expansion has led to encroachment and development on unstable slopes and unplanned construction and frequent violation of building by-laws and regulations. Significant areas of the city experience constant displacement due to the presence of relatively weak rock formations comprising of schists and phyllites. While some urban areas have been completely abandoned due to the structural damages in residential housing, schools, and office buildings, often these buildings are simply repaired or replaced.

Gangtok is draped over several relatively steep hillsides. In this study, we have used synthetic aperture radar interferometry (InSAR) to understand the patterns of displacement better, highlighting areas prone to landslides. The rates of movement of these highly urbanized unstable areas have been measured using data collected by the Sentinel-1 satellites between 2015 and 2021. Field investigations have also confirmed the ongoing ground surface displacements shown in the InSAR results.

Discretely bounded areas in Gangtok are moving at rates sometimes exceeding 12 cm/year. In this study, we concentrate our analysis on three landslide areas where people are residing: Tathenchen, Chanmari and Upper- and Lower-Sichey. In each of these areas, movement is continuous throughout the year. However, distinct periods of acceleration and deceleration are clearly linked to seasonal monsoon rainfall. For example, the velocity of the Upper Sichey landslide varies from about 3 cm/year to 7 cm/year, with peak velocity being reached shortly after peak precipitation each year. In addition, less than half of households in the region are connected to a wastewater network, resulting in significant amounts of water seeping into the local ground.

The type of displacement information obtained by InSAR monitoring is helpful for developing effective mitigation strategies that can limit landslide damage. For example, while rainfall cannot be controlled, better drainage networks can mitigate the local effects. In a broader perspective, the data can be used within urban development planning to identify risk areas and monitor potential zones of catastrophic collapse.

How to cite: Dehls, J. F. and Bhasin, R. K.: Living on landslides: seasonal rainfall effects on rates of movement in highly urbanized unstable areas in Gangtok, Sikkim Himalaya, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1661, https://doi.org/10.5194/egusphere-egu22-1661, 2022.

Test applications
09:34–09:41
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EGU22-13072
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Virtual presentation
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Daniele Ehrlich, Thomas Kemper, and Filip Sabo

 

 

Mountains socio-ecological system are both complex and vulnerable. Europe’s mountain socio-ecological system have evolved over millennia and continue to adapt to the pressure of a changing climate and to changing societal demands. Scientist and practitioners have now at disposal a number of datasets to better understand socio-ecological dynamics on Europe’s mountain, including the European Settlement Map (ESM), a 2x2  m resolution building map generated for 39 European countries including Turkey (Sabo et al 2021). The map is produced based on very high spatial resolution satellite imagery form a mix of sensors acquired through the European Coperncius program and a combination of ancillary datasets including land use. The 2 x 2 m2 spatial resolution map is well suited to study and quantify the presence of buildings in small settlements typical of mountain areas. The settlement map distinguishes between residential and nonresidential buildings. It covers the epoch 2013 and 2018 and thus allows quantifying the change in the building stock between the two epochs. The datasets is particularly suited to assess exposure- and change in exposure - to natural hazards, to assess accessibility and cost of transport. It can be used as a spatial infrastructure to model societal impact on protected areas and on ecosystem services. The map will be combined with population data from censuses to provide insights on depopulation in the more marginal mountain areas of Europe as well as to assess the growth of buildings and infrastructure in the municipality with higher rate of development.  The datasets will be available as open source, and feedback from the mountain community of researcher and practitioners will be welcome to understand the interest for this information and the need for future map updates.

How to cite: Ehrlich, D., Kemper, T., and Sabo, F.: The European Settlement Map. A fine scale European wide building map suited to quantify human presence in mountain areas of Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13072, https://doi.org/10.5194/egusphere-egu22-13072, 2022.

09:41–09:48
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EGU22-718
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Presentation form not yet defined
Saad AlHumidan

Buraydah is the capital city of Al-Qassim Region and located in the northcentral of Saudi Arabia at the heart of the Arabian Peninsula. Buraydah lies at equidistant from the Red Sea to the west and Arabian Gulf to the east. It is a part of the Buraydah quadrangle. The entire Buraydah quadrangle is underlain by Phanerozoic sedimentary rocks of the western edge of the sedimentary basin that occupies the Arabian shield. These sedimentary rocks are cropped out and have been separated by depressions of varied width commonly occupied by eolian deposits (nafud). Buraydah quadrangle is part of Unayzah Formation. In general, the Unayzah Formation is composed of cycles of cross-bedded, fine to coarse grained quartz sandstones, siltstone, vary colored clay stones, and thin beds of argillaceous limestone. Such deposits cover a substantial area in the eastern part of the quadrangle. Buraydah has a hot desert climate (Köppen climate classification BWh), with long, extremely hot summers and short, very mild winters. Precipitation is very low, which falls almost entirely between November and May, leaving summers extremely dry. The city is known for its dates festival which is the biggest in the world with various types of dates, it’s called the city of dates. On November 8, 2021, the United Nations Educational, Scientific and Cultural Organization "UNESCO" included the city of Buraydah within the UNESCO Network of Creative Cities, in the field of gastronomy. It has experienced a very high rates of population growth, in 2010 it was 614,093 growing to an estimation of 745,353 in 2021. The sewage services of Buraydah is still under processing. The main procedure applied there is digging and rebuilding a wide hole in front of each building to collect the sewage water in it and artificially dewatered by time to time. Different types of geological hazards are noted including land subsidence and earth fissures, sinkholes, expansive soils, and flash floods. A wide variety of recent geological hazards have been reported in several areas, causing significant human and property losses. Human activities, most notably groundwater extraction, infrastructure development, and agricultural activities, have induced unstable conditions.

How to cite: AlHumidan, S.: Geological Risk Hazardous Potentials of Buraydah City, Saudi Arabia  , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-718, https://doi.org/10.5194/egusphere-egu22-718, 2022.

09:48–09:55
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EGU22-12453
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ECS
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Virtual presentation
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Azzurra Lentini, Beatriz Benjumea-Moreno, Stephanie H. Bricker, Vittorio Chiessi, Devleeschouwer Xavier, Jorge P. Galve, Guido Giordano, Paolo Maria Guarino, Timothy Kearsey, Gabriele Leoni, Luca Pizzino, Luca Maria Puzzilli, and Francesco La Vigna

The Urban Geo Footprint (UGF) is a project currently developed in the framework of the EuroGeoSurvey Urban Geology Expert Group (UGEG) and specifically focused on the geo-environmental pressures in urban areas.

The main goal of the study is to set up a classification tool (UGF) aimed to identify the main geological features that could influence and/or interfer with (ongoing) anthropic activities within urban catchments.

The following main drivers are defined in the «UGF framework»: Geology, Climate, Geohazards, Geomorphology, Subsoil anthropic pressure. Each driving factor is articulated in quantitative and indexed (using scores) parameters. At the present early stage all these parameters are going to be indexed and weighted based on two levels of investigation: “basic” and “advanced”. The final result for each city is the “UGF INDEX”  coming from the combination of all the drivers specific scores. The higher the index value, the higher the geotechnical and environmental complexity of the urbanized catchment.

The expected outcomes of the UGF urban areas indexing are:

  • A classification of cities according to their geological setting and climatic features, eventually allowing their clustering and supporting sharing of knowledge and capabilities among urban areas.
  • Better understanding of geo-environment processes possibly interacting with urban subsurface and ground infrastructures, thus also encouraging and support cities’ subsurface resilience for sustainable (future) growth.
  • Help for better assessing the ‘economic’ and ‘social well-being’ benefits (i.e. in terms of ‘geological resilience’) that could derive from urban planning associated to subsoil knowledge.
  • A fact-sheet referred to the subsoil of each city, to be progressively updated.

Other objectives of the project are:

  • Contributing to develop a method for the comparison of data from different environmental urban contexts.
  • Improving the European collaboration and, therefore, the exchange of ideas on good practices to increase urban areas’ resilience.
  • Improving citizens' awareness of both the resources and the threats associated with geology.
  • Produce a tool for decision makers support (e.g. urban planning, hazards prevention) in order to obtain economical and social well-being benefits.

How to cite: Lentini, A., Benjumea-Moreno, B., Bricker, S. H., Chiessi, V., Xavier, D., Galve, J. P., Giordano, G., Guarino, P. M., Kearsey, T., Leoni, G., Pizzino, L., Puzzilli, L. M., and La Vigna, F.: Clustering urban areas by a geological point of view: The Urban Geo Footprint tool , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12453, https://doi.org/10.5194/egusphere-egu22-12453, 2022.

09:55–10:00
Policy
Coffee break
Chairpersons: Vikki Thompson, Chloe Brimicombe, Eunice Lo
10:20–10:30
10:30–10:37
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EGU22-5348
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ECS
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Highlight
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Virtual presentation
Carlos Mesta, Gemma Cremen, and Carmine Galasso

In our rapidly urbanizing world, many hazard-prone regions face significant challenges when it comes to risk-informed urban development. This study specifically addresses this issue by investigating evolving spatial interactions between natural hazards, ever-increasing urban areas, and social vulnerability in Kathmandu Valley, Nepal. The methodology used in this work considers: (1) the characterization of flood hazard and liquefaction susceptibility using pre-existing global models; (2) the simulation of future urban built-up areas using the cellular-automata SLEUTH (Slope, Land use, Excluded areas, Urban extent, Transportation, Hillshade) model, which requires satellite imagery for statistical calibration and validation; and (3) the assessment of social vulnerability using a social vulnerability index tailored for the case-study area. Results show that the total built-up area in Kathmandu will increase to 352 km2 by 2050, which is effectively double the equivalent 2018 figure of 177 km2. The most socially vulnerable villages will account for 29% of the total built-up area in 2050, which is 11% more than their current proportion. Built-up areas in the 100-year and 1000-year return period floodplains will respectively increase from 38 km2 and 49 km2 today to 83 km2 and 108 km2in 2050. In the same time frame, built-up areas in liquefaction-susceptible zones will expand by  13 km2 to 47 km2. The results of this study illustrate how, where, and to which extent risks from natural hazards can evolve in socially vulnerable regions. Ultimately, this study emphasizes an urgent need to implement effective policy measures (e.g., land-use regulations) for reducing tomorrow's natural-hazard risks.

How to cite: Mesta, C., Cremen, G., and Galasso, C.: Modelling increasing natural-hazard risk due to urban growth in Kathmandu Valley, Nepal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5348, https://doi.org/10.5194/egusphere-egu22-5348, 2022.

10:37–10:44
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EGU22-1640
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ECS
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Virtual presentation
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Sarah Chapman, Cathryn E Birch, John H Marsham, Cherie Part, Sari Kovats, and Shakoor Hajat

Children (< 5 years) are highly vulnerable during hot weather, however the impacts of past and future warming on child mortality has never been estimated. Here, we use CMIP6 global climate models to quantify, for the first time, the heat-related child mortality that has already occurred (1995 – 2020) in Africa due to climate change, as well as estimate future burdens (2020 – 2050). By 2009, heat-related child mortality was already double what it would have been without climate change and outweighed any contributions from general improvements in development. Under a high emission scenario (SSP585) mortality will double by 2049 compared to 2005 - 2014. Mitigation will save lives; if 2050 temperature increases are kept to 1.5ºC, approx. 3900 – 6300 children could be saved annually in Africa compared to the SSP585 scenario. Our findings support the need for urgent mitigation and adaptation measures to save lives now and in the future.

How to cite: Chapman, S., Birch, C. E., Marsham, J. H., Part, C., Kovats, S., and Hajat, S.: Past and predicted climate change impacts on heat-related child mortality in Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1640, https://doi.org/10.5194/egusphere-egu22-1640, 2022.

10:44–10:51
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EGU22-2983
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On-site presentation
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Ales Urban, Osvaldo Fonseca-Rodríguez, Claudia Di Napoli, and Eva Plavcová

While previous research on historical changes in heat-related mortality observed decreasing trends over the recent decades, future projections suggest increasing impact of heat on mortality in most regions of the world. This study aimed to analyse temporal changes in temperature-mortality relationships in Prague, Czech Republic in the warm season (May-September), using a daily mortality time series from 1982 to 2019. To investigate possible effect of adaptation to increasing temperature, we divided the study period into four decades (1980s–2010s). We used conditional Poisson regression models to identify decade-specific relative risk of heat-related mortality and to calculate the annual number of heat-attributable deaths and the heat-attributable fraction of total warm season deaths. We estimated their trends over the whole study period by a generalized additive model with non-parametric smoothing spline. Our results showed that the unprecedentedly hot 2010s was associated with approximately twice as large relative risk of heat-related mortality than in previous decades. This resulted in the reversal of the trend in heat-attributable mortality in the 1990s and its increase during the last two decades. Our findings highlight the importance of further improvement of adaptation measures such as heat-and-health warning systems to protect the heat-susceptible population.

How to cite: Urban, A., Fonseca-Rodríguez, O., Di Napoli, C., and Plavcová, E.: Temporal changes of heat-attributable mortality in Prague, Czech Republic, over 1982–2019, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2983, https://doi.org/10.5194/egusphere-egu22-2983, 2022.

10:51–10:58
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EGU22-3167
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ECS
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Virtual presentation
Wan Ting Katty Huang, Gabriele Manoli, Isobel Braithwaite, Andrew Charlton-Perez, Christophe Sarran, and Ting Sun

Climate change is expected to increase heat-related mortality risks. However, mortality risks associated with cold weather, which can also occur during summertime, are expected to decrease. The overall impact of temperature changes on summer average risk may therefore evolve differently than the risk associated with heat extremes. A similar, though less pronounced, picture can also be painted for the impact of urban heat island on mortality risk. In two separate studies, we highlight the differing impacts of warming on summer mean versus extreme heat-related mortality risk. Factors such as the local climate and vulnerability to heat play a role in mediating the net summer average impact, while a clear enhancement of risk during extreme heat events is expected in association with both climate change and urban heat island effects. These findings provide a more comprehensive picture of the potential impact of climate change and urbanisation on summer temperature-related mortality risks, which may be relevant for adaptation and mitigation strategies.

How to cite: Huang, W. T. K., Manoli, G., Braithwaite, I., Charlton-Perez, A., Sarran, C., and Sun, T.: Impacts of climate change and urban heat island on mortality risk: summer average vs. extreme heat events, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3167, https://doi.org/10.5194/egusphere-egu22-3167, 2022.

10:58–11:05
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EGU22-5183
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ECS
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Presentation form not yet defined
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Samuel Lüthi, Christopher Fairless, Erich M. Fischer, Ana M. Vicedo-Cabrera, and David N. Bresch

The risk of extreme heat mortality is ever increasing with the rapidly changing climate. With the collision of several mega-trends – aging societies, urbanization, inequality – the need for a comprehensive heat mortality risk analysis is growing. Here, we present a probabilistic analysis of the impact of extreme heat on city-scale mortality, demonstrated for more than 750 locations around the world. First results show that heat-related excess mortality of a 100-year summer in the climate of 2000 must be expected roughly every ten to twenty years in today’s climate for most locations.

We produce the probabilistic risk assessment for heat mortality by building on the open-source natural catastrophe risk platform CLIMADA (CLIMate ADAptation). We combine state-of-the-art epidemiological time series analysis methods with single model initial condition large ensemble (SMILE) climate model output. The epidemiological analysis relies on quasi-Poisson regression time series analyses and requires daily city-level mortality data which we have for more than 750 locations through the MCC (Multi-Country Multi-City) Collaborative Research Network database. This analysis results in city-specific risk of exceedance mortality as a function of temperature. The SMILE approach takes a climate model and runs it multiple times with perturbed initial conditions but using the same climate scenario. It thus indicates multiple physically consistent and plausible pathways of the climate which can be used for a probabilistic risk assessment. This allows estimation of tail-risks and quantification of return-period-based mortality impacts. We used SMILE output of seven different climate models, totaling 270 model runs, to estimate impacts and uncertainties of tail risks.

Communicating risk using (shifts in) return periods is helpful to start dialogues with government authorities, city planners and decision makers, as such metrics are commonly used to prepare for natural catastrophes

How to cite: Lüthi, S., Fairless, C., Fischer, E. M., Vicedo-Cabrera, A. M., and Bresch, D. N.: Rapid changes in return periods of heat-related mortality extremes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5183, https://doi.org/10.5194/egusphere-egu22-5183, 2022.

Other Impacts and Applications
11:05–11:12
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EGU22-4700
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ECS
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Virtual presentation
Ritika Kapoor, Carmen Alvarez-Castro, Clare Heaviside, Enrico Scoccimarro, Stefano Materia, and Silvio Gualdo

Global temperatures have shown a warming trend over the last century, mainly as a result of anthropogenic activities. Rising temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity. In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat related deaths are on a rise.

Over India, the heat waves occur during the months of April to June and can impact various sectors including health, agriculture, ecosystems and the national economy. In May 2015, a severe heat wave due to the delayed onset of southwest monsoon affected parts of south-eastern India, which claimed more than 2500 lives. Preliminary results show the prevalence of Heat events in six different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months.

We consider daily maximum temperatures and NOAA’s Heat Index (HI), a combination of temperature and relative humidity (also known as apparent temperature) which gives an insight into the discomfort because of increment in humidity. It is important to take HI along with temperature anomalies, since humidity also plays a role in transitional period.

Heatwaves over India are known to be linked with mortality and have indirect impacts on human health. To evaluate the heat related risk of mortality on Indian population, indicators and clusters of heat events were computed by taking into account population weighted temperature exposure.

How to cite: Kapoor, R., Alvarez-Castro, C., Heaviside, C., Scoccimarro, E., Materia, S., and Gualdo, S.: Heat events in the Indian subcontinent under a warming climate scenario: Detection and Implications on human health, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4700, https://doi.org/10.5194/egusphere-egu22-4700, 2022.

11:12–11:19
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EGU22-12513
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ECS
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Presentation form not yet defined
Jonas Van de Walle, Oscar Brousse, Lien Arnalsteen, Chloe Brimicombe, Disan Byarugaba, Matthias Demuzere, Eddie Jjemba, Shuaib Lwasa, Herbert Misiani, Gloria Nsangi, Felix Soetewey, Hakimu SSeviiri, Wim Thiery, Roxanne Vanhaeren, Ben Zaitchik, and Nicole van Lipzig

With ongoing climate change and rapid urbanization, exposure to severe heat is expected to accelerate in tropical East African cities. Yet not all parts of the city are equally vulnerable. The present-day intra-urban heat stress variation in Kampala, the capital city of Uganda, is quantified by deriving the daily mean, minimum and maximum Humidex Index from a network of low-cost temperature and humidity sensors operational in 2018-2019. Heat is shown to be heterogeneously distributed over the city, with a daily maximum intra-urban Humidex Index deviation of 6.4°C averaged over the observational period, but reaching 14.5°C on the most extreme day.

Also extreme heat is heterogeneously distributed over the city, putting local populations at risk of great discomfort or health danger. One station in a dense settlement reports a daily maximum Humidex Index above 40°C in 68% of the observation days, a level which was never reached at the nearby campus of the Makerere University, and only a few times at the city outskirts. About 75% of this intra-urban heat stress variability is explained by the Normalized Difference Vegetation Index (NDVI), though strong collinearity is found with other variables like impervious surface fraction and population density.

Overall, our results highlight the importance of (i) including both temperature and humidity in heat stress studies, (ii) urban greening in city planning, and (iii) large intra-urban heat stress variations in heat action planning in tropical humid cities.

How to cite: Van de Walle, J., Brousse, O., Arnalsteen, L., Brimicombe, C., Byarugaba, D., Demuzere, M., Jjemba, E., Lwasa, S., Misiani, H., Nsangi, G., Soetewey, F., SSeviiri, H., Thiery, W., Vanhaeren, R., Zaitchik, B., and van Lipzig, N.: Dangerous heat in dense settlements in a tropical African city, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12513, https://doi.org/10.5194/egusphere-egu22-12513, 2022.

11:19–11:26
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EGU22-2982
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ECS
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Presentation form not yet defined
Je-Woo Hong and Jin Han Park

Using high-resolution floating population (50 m) data, heatwave hotspots in a city (Gimhae, Gyeongsangnam-do Province) in Korea are identified. So far many assessment tools (ex., VESTAP for vulnerability and MOTIVE for potential impact in Korea) show only low-resolution results (>1 km, or one result for administrative district). Therefore, most stakeholders for adaptation have difficulty making a decision such as a location decision for a new cooling center and/or shelter for citizens. Simply, we overlap GIS data including a daytime (11:00-16:00) floating population (50 m) based on mobile communication volume, vegetated area and in-land water with 100 m of effective radius, and location of cooling centers with 300 m effective radius. As a result, we find 20 priority locations for heatwave hotspots in a city. This study is supported by “Basic Study on Improving Climate Resilience” (2021-001-03), conducted by the Korea Environment Institute (KEI) upon the request of the Korea Ministry of Environment.

How to cite: Hong, J.-W. and Park, J. H.: Hotspot identification using high-resolution floating population., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2982, https://doi.org/10.5194/egusphere-egu22-2982, 2022.

11:26–11:33
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EGU22-8073
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ECS
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Virtual presentation
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Smrati Gupta

Authors:

Smrati Gupta1,2*, Yogesh K. Tiwari1, J. V. Revadekar1, Pramit Kumar Deb Burman1, Supriyo Chakraborty1, Palingamoorthy Gnanamoorthy3,4

1Indian Institute of Tropical Meteorology, Pune, Ministry of Earth Sciences, Govt. of India

2Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India

3Coastal Systems Research, M. S. Swaminathan Research Foundation, Chennai, India

4Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Menglun, China

Abstract           

A significant amount of the major greenhouse gas, carbon dioxide (CO2), released into the atmosphere is sequestered by the terrestrial biosphere. Climatic parameters such as temperature, precipitation, soil moisture, etc., modulate this sequestration capacity or sink in varied limits. A little information is available on the impact of extreme temperatures on the terrestrial biosphere sequestration of atmospheric CO2. This study explores the modulation in the terrestrial sink of CO2 caused by the frequently occurring extreme temperature phenomenon such as heatwaves over the Indian domain. Heatwaves are extreme temperature phenomena extending from the North-west Indian region towards the south-east region, occurring primarily in the pre-monsoon season of March-May (MAM), sometimes prolonged until June. The high intensity and duration of heatwaves during the season lead to the loss of human work capacity, health, economic losses, and even lives. The year 2015 witnessed one of the dreadful heatwave events in recent years, resulting in the loss of more than 2500 human lives within a season owing to heatwaves. The frequency and intensity of heatwaves are projected to increase further soon globally, including India, in the light of global climate change. It is not only of concern for human resources.

From the biosphere perspective, the terrestrial sink of CO2 has also been studied to get affected by heatwaves. Temperature is one of the prime factors responsible for photosynthesis and ultimately for the available atmospheric CO2 fixation by the plants. As such, the CO2 fixation by the biosphere is affected during MAM season due to limited reduced soil moisture in this hot and dry season, leading to higher atmospheric CO2 concentrations. In this study, we examine the sub-seasonal variability in the atmospheric CO2 observed within MAM, driven by subdued fixation by ecosystems in the presence of extreme temperature phenomena like heatwaves. Here, available observations of CO2 flux or Net Ecosystem Exchange (NEE) flux from MetFlux India Project funded by the Ministry of Earth Sciences, India, studied in conjunction with the retrieved atmospheric and columnar CO2 concentrations from instruments aboard Atmospheric Infrared Sounder and Orbiting Carbon Observatory-2 satellites during the heatwave period of the year 2015. Our results suggest during a heatwave period, there is an initial increase in carbon uptake by the ecosystem with the temperature rise. But a further rise in temperature after some critical high temperature (~ 32 ͦ C) tends to reduce CO2 uptake compared to the non-heatwave period of the same season. The satellite retrievals also noticed an increase in atmospheric CO2 concentrations by 2-3 ppm during the heatwave period. The impact and feedback of heatwaves on the biospheric component of the carbon cycle is one of the significant outcomes of this study.

How to cite: Gupta, S.: A study on the linkage between extreme temperature and atmospheric Carbon dioxide variability over India, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8073, https://doi.org/10.5194/egusphere-egu22-8073, 2022.

11:33–11:40
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EGU22-13336
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Presentation form not yet defined
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Cascade Tuholske, Catharina Latka, Kathy Baylis, Jordon Blekking, Rachel Green, Manny Kim, Patrese Anderson, Kelly Caylor, and Chris Funk

Extreme hot-humid heat impacts both urban and rural livelihoods, reducing labor output and damaging health. As such, increasing exposure to hot-humid heat may be reducing food security for both rural and urban household in Africa. Yet, due to a lack of fine-resolution meteorological data, we have a poor understanding of where urban and rural exposure to hot-humid heat is impacting food security across the continent’s diverse geographies. To fill this gap, using more than 20,000 geo-located surveys from the Demographic and Health Survey Program, we map how the spatial relationship between household-level food security and heat exposure has varied among rural and urban populations since the 1980s. We document spatial and temporal heterogeneity, identifying areas of concern where dangerously hot-humid heat is increasingly co-impacting both urban and rural food security outcomes. Given that hot-humid heat waves will worsen across much of Africa as we warm our climate, our results add to growing calls for effective extreme heat warning systems, including seasonal forecasts, tailored to reduce the impacts of hot humid-heat for all people, regardless of where they live.

How to cite: Tuholske, C., Latka, C., Baylis, K., Blekking, J., Green, R., Kim, M., Anderson, P., Caylor, K., and Funk, C.: Extreme heat impacts on food security in Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13336, https://doi.org/10.5194/egusphere-egu22-13336, 2022.

11:40–11:50