Combining Theory and Practice in Landslide Risk Mitigation
By Roquia Salam, on 21 October 2024
Takeaways from the International School on Landslide Risks Assessment and Mitigation (LARAM)
I had the opportunity to attend the International School on Landslide Risk Assessment and Mitigation (LARAM), organized by the Geotechnical Engineering Group (GEG) at the University of Salerno, Italy, from September 9th to 20th, 2024. 39 PhD students and three early-career researchers from 30 universities across Europe and beyond, representing 20 different countries, participated in the event to share their research on landslide disasters. Renowned professors and stakeholders working in landslide disaster risk mitigation from various countries, including Italy, Austria, Norway, China, Switzerland, Spain, the Netherlands, Germany, Serbia, Croatia, and Greece, shared their insights. They discussed and showed tutorials on key topics such as an introduction to landslides, landslide risk theory, landslide modelling, risk analysis and zoning, monitoring and mitigation, risk management, and governance.
Here, I share some key takeaways from LARAM School, with a focus on conceptual insights rather than the detailed physical and mathematical aspects discussed during the sessions.
Human Influence and Landslide Dynamics
Nowadays, landslide disasters are no longer considered purely natural; human activities significantly influence them. Actions such as altering landscapes, unplanned urbanization, deforestation, and climate change (leading to extreme rainfall and temperature shifts) can trigger landslides in various ways. Among climatic factors, unevenly distributed heavy rainfall is a major contributor, as it causes slopes to become oversaturated and increase pore water pressure leading to slope instability. Landslides can be likened to human cancer: just as cancer is triggered by uncontrolled cell growth, landslides occur when soil becomes unstable due to various triggers. Of the many types of landslides, flow-like landslides are the most dangerous, as they can propagate over large areas. Therefore, proper land management is essential to mitigate landslide risks, as these events cause significant disruptions, affect ecosystems, and highlight the importance of early detection and intervention.
Landslides do not occur randomly on hills or mountains but tend to happen near weak points such as cracks, fault lines, joints, and drainage channels. A first failure (landslide) usually occurs at these weak points, triggered by external factors. This initial failure weakens the slope, altering its structure, and creating conditions for secondary failures in the surrounding areas. These secondary landslides increase the susceptibility of the region, leading to a feedback loop that can trigger additional, larger landslides. Hence, geological and geomorphological knowledge is crucial for landslide research.
Monitoring and Case Study
After a landslide, the stratigraphy or the layered structure of the soil and rock in the affected area undergoes significant changes. These alterations can disrupt the stability of the landscape, making previous risk assessments unreliable. This is why it becomes essential to update risk maps based on new geological and geotechnical conditions. For instance, landslides can expose deeper, less stable layers or alter the composition of surface materials, which may now be more prone to further movement.
From a soil science and physical science perspective, it is crucial to assess the presence and behaviour of water tables in the affected zone. Water tables influence slope stability, and multiple water tables at different depths can increase the complexity of the risk. The type of water table (confined or unconfined) determines how water moves through the soil, affecting its weight and cohesion.
Monitoring pore water pressure over time is a key factor in evaluating the soil or rock’s shear strength. Pore water pressure refers to the pressure exerted by water within the pores of the soil. When this pressure increases due to rainfall, groundwater infiltration, or changes in drainage it reduces the friction between soil particles, weakening the overall structure. This reduction in shear strength, combined with increased shear stress from external forces like gravity or added water weight, can trigger landslides or make the area more susceptible to future failures. Understanding these dynamics is critical for accurate hazard assessments and mitigation strategies.
Modelling and Mapping Landslide Risks
Recent scholars have modelled landslides to mitigate risks using three widely employed methods: mathematical, constitutive, and numerical. However, an important step that is often overlooked is the observation of phenomena through community surveys, stakeholder interviews, field visits, laboratory tests, and reviewing existing research. A purely physical science-based model may produce statistically excellent results but may significantly deviate from reality. Therefore, incorporating field observations is essential to make the results more practical and reliable, a principle applicable to other disasters as well.
Landslide inventories are the foundation for modelling landslide disasters. Today, satellite imagery is extensively used to create these inventories, which helps geologists and geomorphologists. However, it remains crucial to cross-check satellite-generated inventories with field visits, as artificial intelligence (AI) used to detect landslides in images is not 100% accurate. Additionally, the nature of landslides varies by location, catchment area, and even slope, making geological knowledge necessary for inventory classification.
There are two main approaches to mapping landslide susceptibility: bottom-up and top-down. It is always recommended to perform a back-analysis of past landslides to calibrate models. The bottom-up approach, although thorough, is time-consuming and impractical for large areas within 3-4 years. AI typically uses this approach, but it would be beneficial for researchers to guide AI in employing top-down methods as well. The top-down approach is efficient for large-scale landslide risk mitigation, allowing researchers to first map a large area and then categorise it into different zones based on homogenous patterns of landslides, geology, hydrology, and other factors. This makes it easier for risk managers to implement similar mitigation strategies across similar zones, offering a more practical and effective solution than the bottom-up approach.
Early Warning Systems and Mitigation
Monitoring landslides and providing early warnings (EW) are vital to reducing landslide risks. Although satellite imagery is widely used for landslide monitoring, it is not ideal for fast-moving landslides (e.g., rock falls), which can occur in minutes, making it impossible to analyse their velocity due to the fixed revisit times of satellites. Multi-hazard monitoring is also essential, as landslides can be triggered by other disasters such as earthquakes, floods, and storms, which compound the overall damage. Developing an effective EW system requires collaboration between academics, hydrologists, geologists, geomorphologists, climatologists, programmers, and stakeholders. Although effective EW systems can reduce landslide risks, they depend largely on the willingness of the affected communities to act on the warnings. Often, people are unwilling to relocate even after receiving an EW, putting their lives in danger. Moreover, early warnings are not always disseminated widely; in Switzerland, for example, only around 30% of affected people receive warnings, with this figure dropping to as low as 2% in some cases.
It is crucial to ensure that the recipient of the EW fully understands the different alert levels and their implications. Clear communication at each stage helps the receiver take appropriate actions based on the level of threat, reducing confusion and improving response effectiveness.
Beyond early warnings, mitigation strategies are crucial. Before implementing any structural mitigation measures, it is wise to consider the long-term consequences of such structures at least 15 years down the line. While a structure may provide an immediate solution to current problems, it could cause more harm than good in the future (long-term). Measures that work perfectly in one area may not be effective in another, even within the same region. It is essential to design mitigation strategies for the unique conditions of each location, using place-specific risk analysis to ensure the most effective approach for local hazards and vulnerabilities. Nature-based solutions, such as planting trees, are effective for all types of landslides, but they may take a long time to yield results.
Roquia Salam is a first-year PhD student at UCL RDR, supervised by Dr Bayes Ahmed (primary) and Professor Peter Sammonds (secondary). Her PhD research topic is “Explainable AI-Driven Digital Twin Technologies for Developing Rainfall-Induced Landslide Forecasting Systems in Bangladesh.” Her work explores hazards, capacity, vulnerability, and disasters using both qualitative and quantitative approaches, with a focus on promoting disaster resilience.
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Flooding in Bangladesh: Understanding the Complex Drivers and Impacts
By Jasmine Andean and Siyao Li, on 3 September 2024
Floods all around the world have been increasingly mediatised in recent years, thanks to growing awareness of the impacts of climate change on the intensification of the global hydrological cycle and associated hydrometeorological hazards. This is true for Bangladesh, where the intense recent floods of 2020 and 2021 were fairly present in Western media outlets. Again, in June and July 2024, the heavy rainfall and consequent flooding in northern Bangladesh were discussed in British media including The Guardian and the BBC.
In many of these media accounts, climate change is seen as the primary cause of flooding in Bangladesh. This reflects wider narratives in development circles that climate change is the primary factor contributing to severe flooding in Bangladesh. It is unsurprising, then, that development funding in Bangladesh, too, is being increasingly earmarked for climate adaptation projects.
The notion of climate change as the primary cause of flooding in the country may be reductive and could have serious implications for the efficiency of development and adaptation projects and their impacts on communities.
The Bangladesh context
Bangladesh is situated in the downstream of three major rivers: the Brahmaputra (Jamuna), the Ganges (Padma) and the Meghna, flowing from neighbouring countries like India and China. The average annual combined discharge rate of these rivers into the Bay of Bengal is 100,000-140,000m3/s. Bangladesh’s weather system is dominated by the Indian monsoon, in which heavy rainfall during the summer monsoon months is typical and expected. Flooding is therefore normal in Bangladesh, and has occurred for centuries; in fact, in an average year, about 20-25% of the country’s area is expected to be flooded.
In a once-a-century event, the land affected can be up to and beyond 60% – this annual cycle of flooding also brings benefits to the ecology and economy of the country, with the fresh sediment deposited on river floodplains by floodwaters making the soil extremely fertile, promoting crop production.
Thus, previous programmes to stop flooding entirely have been ineffective and have, in some cases, brought negative consequences and environmental damages. For example, the government of Bangladesh and various international development actors such as the World Bank constructed coastal embankments (also known as polders), sometimes intending to entirely stop the inundation of land. This infrastructure has protected many communities in coastal Bangladesh from storm surges and inundation resulting from tropical cyclones, but created water-logging and challenges for agriculture and livelihoods, as the previously highly fertile floodplains became less fertile and conducive to crop cultivation due to the obstruction of the floodwaters depositing sedimentation to renew soil fertility and natural land development. The land surface elevation within these coastal embankments is much lower than its adjoining floodplains making them vulnerable to water-logging and poor drainage problems. Such initiatives that attempt to obstruct the natural ecology and hydrological processes in Bangladesh, actively working against nature, fail to address the true causes of flood damage and risk unintended harm to communities. Narratives that paint all flooding in Bangladesh as a consequence of climate change risk justifying or promoting such initiatives.
The fact that floods are natural and in some ways necessary in Bangladesh does not negate the fact that when combined with vulnerabilities, floods can also bring serious socioeconomic consequences and lead to a loss of life, livelihood and health in underprepared and vulnerable communities across Bangladesh.
Source A: Asian Development Bank (ADB). 2015. Capacity Building for Disaster Risk Finance in Bangladesh. Consultant’s report. Manila (TA 8144-BAN). Note: Economic losses are expressed in 2014 dollars to estimate the relative economic impact of events over the different years.
Source B: Annual Flood Report 2021. Flood Forecasting and Warning Centre (FFWC), Bangladesh Water Development Board (BWDB).As seen in Figure 1 (A), a statistically significant relationship is found between the area affected and the economic loss incurred nationally; the more land is affected, the more economic losses occur, and the more households face loss in their assets and livelihoods.
However, not all communities and demographics are equally affected by this economic loss, as some groups have fewer strategies for coping with the loss of income and assets. For example, during severe flash flooding in 2017 in the Haor wetland region in northeastern Bangladesh, a popular adaptation strategy for households facing income disruptions was to temporarily change their occupation, including working in neighbouring communities or nearby urban areas. However, women were less able to adopt this resilience strategy due to them not being allowed to work outside the home and beyond Haor communities. This made women and female-headed households face higher losses of income and most likely compromised their ability to recover from the floods. However, it is also important to note the majority of households who changed their income strategies also experienced a loss in daily income, and groups other than women were also particularly impacted by this loss. For example, the elderly and those whose livelihoods were highly reliant on natural resources also faced higher than average loss of income.
In some cases, coping strategies may also exacerbate economic loss and vulnerability. An example of this is seen in the char lands of Bangladesh. Char lands are riverine islands and sandbars that form due to the accumulation of sediments from major rivers and their tributaries) of Bangladesh. Approximately 6.5 million people live on these chars, with flood-induced temporary displacement occurring on average every 5 years. In a year of extreme flooding, a household may be displaced up to 3 times in a single year. Although temporary migration has at times been described as an adaptation strategy, this repeated setback of livelihoods inflicts chronic economic, social and psychological costs on char inhabitants, exacerbates the process of impoverishment and impedes development as the recurring losses exceed recovery capacity, preventing the accumulation and growth of assets. This creates a cycle of poverty that is challenging for the char inhabitants to escape. As floods are becoming more frequent and widespread as a result of climate change, living on char lands and river floodplains will inevitably increase exposure to flooding, and thus, flood risk cannot be reduced.
The drivers of vulnerability in Bangladesh are complex. For example, communities in the chars and flood-prone areas are so exposed to flooding because they have settled on floodplains, driven by extremely high population density. Bangladesh is approximately the size of the State of New York with more than half the population of the United States. As a result, land is scarce, and particularly poorer households find themselves settling on the precarious, yet highly fertile, land of the floodplains.
Although flooding is a prevalent feature of the Bangladesh landscape, much remains to be done to enhance the resilience and address the vulnerabilities of the country’s population. It should also be noted that although flooding is a natural process in Bangladesh and that development programmes should not rely on climate reductive narratives to aim to entirely obstruct them. Furthermore, climate change does seem to be having some impacts on flooding and rainfall variability during the monsoon season in Bangladesh. For example, the seasonality of monsoon rainfall seems to be undergoing some changes, with heavier rains being seen particularly in the pre-monsoon season and less rainfall during the peak (June) monsoon season; this could have considerable effects on agriculture and livelihoods in the country. Further changes are likely to materialise as climate change progresses. The proportion of annual flood-affected area also appears to be increasing, as seen in Figure 1 (B). Considering the correlation between economic loss and the percentage of the area affected, this underlines the urgent need to build resilience to flooding that should take into account of the spatial variability as ‘one size fits all solution’ may lead to maladaptation to climate change.
As it stands, considerable sections of the population of Bangladesh remain trapped in a vicious cycle of high exposure and vulnerability, flooding, and poverty, which in turn exacerbates exposure and vulnerability. To begin to truly address the social, economic, and developmental challenges brought by floods, underlying structures of poverty and inequality must be addressed. Any approach to flood mitigation in the country that fails to reckon with the flood risk framework – specifically vulnerability and exposure – will fall short of preventing flood damage to communities and economic losses.
MAPS Faculty summer interns, Jasmine Andean (Global Humanitarian Studies BSc alumna) and Siyao Li (Second-year Arts and Sciences BASc student) have been supervised by Dr Mohammad (Shams) Shamsudduha, UCL Department of Risk and Disaster Reduction.
The views expressed in this blog are those of the author(s).
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From House to Home: Empowering Refugees with RHome
By Tiffany Mihardja, on 13 May 2024
To many of us, the thought of a house, a home, rings as a familiar thought. We grew up in a house, and over time, the house became a home: a place of love, of belonging, of safety. However, I soon became aware of the poignant reality that not everyone knows of a house, let alone a home. In many war-stricken areas, houses were left in shambles, forcing families to bid farewells to their homes. Growing up in the busy bustles of a metropolitan, Jakarta, I rarely encountered these dimmed-down stories. However, when I visited refugee sites around Indonesia, I soon realized that many kids my age, or those far younger than me, do not have the privilege of calling a place their home.
During my visits to the Cisarua Refugee Learning Center, I was able to personally connect with them and hear their notably powerful stories. The refugee community in Indonesia has long enough been marginalized and tucked away from the care of both public and private sectors. They constantly walk a tightrope of uncertainty and are deprived of opportunities due to their refugee status. It is unfair that these bright individuals are hindered from the opportunity to shine and obtain their full potential solely because they are refugees. Therefore, in 2021, I founded RHome, a charity that works with refugees, as I sought to tap into the power of transforming this seemingly distant and foreign land of Indonesia to become “Our home.”
At RHome we seek to creatively empower youth refugees through hosting painting competitions. Through these community-building painting events, I hope to bring joy to the refugee community during challenging times – especially considering that many enjoy and have a talent for painting. The winners’ creations are then curated into a range of lifestyle merchandise – scarves, tote bags, notebooks, fans, tumblers, etc. The entirety of profits from the sales of our RHome products are allocated to support the refugee community, helping us bridge the provisional gaps of their physiological and educational needs.
Since the inception of RHome, we have hosted many events where communities from all walks of life have united upon a shared mission: to celebrate the refugee community in Indonesia. For example, in the World Refugee Event we hosted in Hadiprana last year, RHome was honoured to highlight the breathtakingly beautiful designs of the refugee children in a dynamically vibrant fashion show attended by spouses of ambassadors and distinguished members of the community. The event was also kindly supported by Ann Mayman (Head of Representative of UNHCR in Indonesia). Through these events, we proactively debunk the myth rendering refugees as “burden”, and instead shed light on how they are some of the most resilient souls equipped with invaluable stories and incredible talents.
RHome has been honored to have received the Diana Award in 2023 and recognized as the SME Champion for the United Nations Women WEP Award in 2022. Additionally, RHome has been kindly featured in various media platforms such as Femina and Tatler Magazine, in which I had the opportunity to showcase RHome’s work and emphasize the importance of advancing social awareness through philanthropic initiatives. Through these awards and media coverage, RHome hopes to challenge the negative stereotypes that society often imposes on refugees and champion the truth through global platforms that our refugee friends are valuable members of our community.
As I continue to work alongside refugee communities in Indonesia, RHome strives to challenge the circulated idea that refugees are “burdens” and instead promote the truth that refugees are resilient souls equipped with invaluable stories and incredible talents. RHome remains committed to evolving into a community cornerstone that provides support for our refugee friends displaced in Indonesia.
Tiffany Mihardja is founder of RHome and a student on the IRDR Global Humanitarian Studies BSc.
The views expressed in this blog are those of the author(s).
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Ukraine Fatigue: how the Ukrainian Student Union rallies global support in times of war
By Sofiia Taran, on 12 March 2024
Last month commemorated the two-year anniversary of the full-scale invasion of Ukraine, an event that, for many, represents a decade-long conflict beginning with the 2014 annexation of Crimea. This war has had devastating impacts on both the military and civilians, leading to widespread destruction, loss of life, and humanitarian crises. This raises fears of a wider conflict in Europe, challenging the post-World War II international order and its legal and security architectures.
Despite substantial support from Ukraine’s international allies, the phenomenon of war fatigue, also known as “Ukraine Fatigue,” emerges as a new challenge after two years of the full-scale conflict. This challenge also affects Ukrainians abroad, who find themselves in a struggle to maintain international awareness and support for their country.
The Ukrainian Student Union (USU) is an organisation that brings together Ukrainian student societies in Universities around the UK. After joining USU in September 2023 as a Partnership Manager, my role was to foster and grow the relationship of Ukrainian youth with international stakeholders and ensure sustained engagement and support from the international arena and work closely with the Uk Parliament for various events.
To bring back the international community’s engagement with the ongoing crisis, our team and I, created a social media initiative for the second anniversary of the war on 24.02.2024 aimed at highlighting the persistent nature of the conflict. This campaign, featuring a flash mob that included 25 Ukrainian societies across the United Kingdom, including the UCL Ukrainian Society, centered an exhibition showcasing Google portraits of Ukrainians alongside the important message, “The war is still ongoing.” This endeavour holds profound significance, as it underscores the terrifying reality of daily casualties on Ukrainian battlefields and civilian population, to remind the global support about the cause.
It is important to acknowledge the repeated struggle for independence that Ukraine has faced in the past, a narrative further explored through a video produced by the SMM team and me. The essence of this campaign is to serve as an explanation and a reminder to the international audience that the resilience of the Ukrainian people has not been happening for 2 or 10 years, but instead it stretches far into past generations.
This campaign stands as a testament to the global community against developing “war fatigue” because of the Ukrainian people that are living in constant battle against Russia. This work underlined the critical need for continuous international support and solidarity with Ukraine amidst its ongoing fight for sovereignty and peace, as…
…the war is still going on…
Sofiia Taran is Partnership Manager at the Ukrainian Students Union and an IRDR BSc student in Global Humanitarian Studies.
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