On September 10th of 2023, Storm Daniel made landfall in northeastern Libya, bringing torrential levels of rain and strong winds (Figure 1). This onslaught of rain caused two big dams in the region to break – the Abu Mansour dam and the Derna dam, 75 metres and 45 metres tall respectively. It is believed that the Abu Mansour dam broke first, after its reservoir was filled beyond capacity. The dam collapsed and sent a rush of water towards the Derna dam further downstream (Figure 2). The Derna dam was already straining from rising water levels and was unable to handle the sudden influx of water from the Abu Mansour dam as well. This subsequently triggered the collapse of the second dam, culminating in an estimated 30 million cubic metres of water being released at once (Cuccia, 2023). It was reported that a 7-metre wave of floodwater was produced, flowing downhill through the mountainous landscape making a direct collision with the city of Derna (Saarinen, 2023). Entire neighborhoods were dragged out to sea by the massive influx of rushing water from both dam collapses and the torrential rain (Figure 3). Currently, over 4300 people have been reported dead, while over 8500 people are still missing (UNICEF, 2023).

Why was this disaster so particularly devastating? 

The combination of increasing storm severity, aging infrastructure, and vulnerable geography were all significant contributing factors. Firstly, the sheer scale of these floods underscores how climate change is altering the frequency of once-in-a-century storms (Intergovernmental Panel on Climate Change, 2023). Huge volumes of rain were recorded, far outside the normal amounts for this time of year. Within the region, the nearby city of Al Bayda recorded 414 millimetres (16 inches) of rain during the storm (Mellen et al., 2023). Derna itself recorded 100 millimetres (4 inches), an anomaly far beyond the city’s average September rainfall of less than 1.5 millimetres (0.1 inches) (Cassidy, 2023). 

At the same time, the aging infrastructure of the Derna and Abu Mansour dams undoubtedly contributed. Reports of cracking and instability had been reported for decades, raising questions surrounding how much these dams have actually been maintained (Figure 4) (Magdy, 2023; Samuels, 2023). Beyond the aging infrastructure itself, it is unclear if, in the face of climate change, the benefits of big dams outweigh the associated risks of disaster. The discourse around big dams has shifted greatly over the last several decades, causing many leading experts to condemn them as too risky to human health and too detrimental to the environment (Boelens et al., 2019; Gohain, 2008). Finally, as it pertains to vulnerable geography, the city of Derna is at high-risk for several reasons. The coastal city is low-lying and uniquely situated at the foot of the Wadi Derna, the narrow river valley that runs from the Jebel Akhdar mountains down to the Mediterranean Sea (Figure 5). There is approximately a 250-metre change in elevation from the first dam to the city centre, allowing the huge rush of water to gain speed as it flowed downhill, ultimately increasing the force with which it impacted the city (Mellen et al., 2023). 

For these reasons, Storm Daniel caused significant destruction, and was indeed the deadliest flood to occur in Libya in over a century (WHO, 2023b). In the wake of the disaster, there remain further concerns for human health as the access to water, sanitation, and hygiene facilities have been extremely reduced. Scientists worldwide are considering how to best prevent such devastation from occurring again. In particular, many are turning towards space-based technologies to aid in the prediction of storms and the creation of early-warning systems. The usage of space-based technologies to predict how many people may become missing or injured in the wake of a natural disaster is also being explored.

The link between climate change and Storm Daniel  

The extent of the devastation from Storm Daniel is vast, yet weather events like this are happening with increasing frequency. Why is this? And why are they also increasing in intensity? To understand this, we first must understand the role of greenhouse gases in our atmosphere. As the sun’s energy travels towards Earth, some of this energy is reflected back into space, while the rest is absorbed by the Earth’s surface and atmosphere. Greenhouse gases in our atmosphere, such as carbon dioxide and methane, re-radiate this heat in all directions, including downwards (Figure 7). In essence, this keeps the lower atmosphere and Earth’s surface warm and prevents the Earth from being inhospitably cold. Problems are arising, however, because the amount of greenhouse gases in our atmosphere has increased drastically, causing an extreme heating of our atmosphere that has never been seen before (Figure 8) (Hansen et al., 2020). With these significant increases in greenhouse gases in the Earth's atmosphere, this re-radiating effect is compounding - leading us to witness an extreme and rapid heating of the Earths' surface.

What role do the oceans play? Water has a much higher heat capacity than air, meaning that it can absorb more heat per kilogram before rising in temperature. As a result, the world’s oceans act as temperature buffers, absorbing excess heat from the atmosphere. In fact, studies have shown that the oceans absorb 90% of the excess heat attributed to climate change (NOAA, 2023a). However, as the sea surface temperatures rise and greenhouse gases continue to accumulate, this ability to act as a heat sink means that the temperature of the oceans are climbing as well (Figure 9) (Johnson & Lyman, 2020). 

Storm Daniel was classified as a Mediterranean tropical-like cyclone. Storm systems such as this have characteristics of both tropical cyclones and hurricanes, making them colloquially known as medicanes. One of the contributing factors to the formation of tropical cyclones and hurricanes are warm ocean waters, although medicanes can still form on the lowest sea surface temperatures of the three types of storms mentioned. This is because warmer ocean temperatures increase evaporation at the sea surface - the warmer the water, the more moisture is in the air (Environmental Defense Fund, 2023). To form a storm, the humid air is dragged aloft when converging winds collide, causing it to move upwards. This water vapor in the air then begins to condense into clouds and rain at higher altitudes, releasing heat into the surrounding air, which in turn causes it to rise further (NOAA, 2023b). As this air continues to rush upwards, more warm moist air spirals in from the sea surface to replace it, ultimately feeding the storm. The result is that storms formed over warmer waters are fed with more water, causing heavier rainfall and increased flooding once the storm hits landfall (Trenberth, 2007).

Storm Daniel was also part of a larger weather pattern known as an Omega block. This refers to a high-pressure system being trapped in between two low-pressure systems, forming the shape of the Greek letter Ω (Figure 10). Omega blocks can cause an abundance of extreme weather at the same time; recall that torrential rains were occurring in Spain and Portugal, as well as in Libya, Greece, and Bulgaria, all while heat waves were recorded the UK and parts of central Europe. They also tend to be particularly devastating because of their stationary nature, sometimes remaining in place for days or weeks at a time, causing extended amounts of extreme weather (Detring et al., 2021). Scientists do not yet fully understand the mechanisms needed for an Omega block to form, although several have drawn a link between Omega blocks and climate change (Woollings et al., 2018). 

The question remains as to whether there is a link between Storm Daniel and climate change. The data is consistent – the oceans are warming. Scientists also know that certain storm types, such as medicanes, draw their energy from warm ocean water and require this heat to form (Cione & Uhlhorn, 2003). Multiple studies have found that, for every 1 degree Celsius of atmosphere warming, the air’s capacity to hold water increases by 7% (Center for Climate and Energy Solutions, 2023). Learn more about this in our article on the relation of extreme precipitation and temperature here. It therefore stands to reason that a warmer ocean, combined with moister air, creates the ideal conditions for tropical storm formation that will lead to an increase in storm frequency. At the same time, however, we do not yet know the link between climate change and Omega blocks. Was Storm Daniel so impactful because of the stationary nature of the block? Or would similar levels of damage have occurred if the storm had formed in isolation? These questions are impossible to answer (Zachariah et al., 2023). What remains clear is that, in a world deeply altered by climate change, significant action needs to be taken to stop the release of greenhouse gases into the environment to prevent the Earth from warming any further.

The Derna dams and changing dam discourse 

Another factor in why Storm Daniel was so deadly in Libya was the dams themselves. Built in the 1970s by a Yugoslavian construction company, both the Derna dam and the Abu Mansour dam were classified as “big dams”, standing at meaning 45 metres and 75 metres tall respectively (Figures 11 and 12) (Tara, 2023). Together, they held a storage capacity of approximately 20 million cubic metres of water and were initially constructed to provide irrigation water for nearby pomegranate and fruit farms (Gazzini, 2023). For visualisation purposes, 20 million cubic metres of water is equivalent to approximately 8000 Olympic-sized swimming pools. 

While they stood stall for several decades, the dams did not have easy lives. They endured years of civil war amongst various unstable and shifting governments. The role that this instability played regarding the structural integrity of the dams is not insignificant. For example, government officials were first made aware of structural deficiencies are far back as the late 1980s, when water began leaking from underneath the dams (Gazzini, 2023). Many years passed until a Turkish construction company was finally hired to carry out repair plans in 2008, although no work actually began until 2010 (Said & Aly, 2023; Woo, 2023). By 2011, civil unrest in Libya was at an all-time high, leading to an uprising which culminated in the overthrow of the Qadhafi government. The Turkish construction company vacated the country amidst the civil war and the dam repair was never completed. Similar circumstances occurred between 2014-2018, during which time another civil war prevented any repair contracts from being fulfilled (Gazzini, 2023). While there were certainly other contributing factors as to why Storm Daniel was so devastating, such as increasing storm severity, it is important to recognize the undeniable impact that political instability had on the structural integrity of the dams. 

Considering the bigger picture, many questions have arisen in recent decades regarding the purpose of big dams in a world impacted by climate change. Revered for their ability to regulate water flow, dams can, and do, provide many essential services that would otherwise be impossible. For example, the creation of year-round water reservoirs (particularly in arid climates), the ability to create hydroelectric power, the impact on irrigation and food production, the potential for flood protection etc. all make dams smart and effective choices. At the same time, however, our understanding of dams has changed greatly since the 1970s. While big dams were once celebrated as major feats of engineering, they are now frequently regarded as aging and obsolete structures that pose serious risks to the environment and human health. Environmentally, it is not hard to see why dams are problematic. Restricting the natural flow of a river changes an aquatic ecosystem entirely - whether it be halting the flow of nutrients, altering the path of migrating species, or destroying downstream environments (Maavara et al., 2020). 

Perhaps the biggest danger of all, however, is the risk of dam failure – as shown in Derna. This is particularly true in a modern world, where climate change impacts every facet of daily life. The frequency of torrential rains, flash flooding, and storm systems is undoubtedly increasing and impacts the risk of dam over-topping and collapse (Intergovernmental Panel on Climate Change, 2023). Dam collapses are now occurring with alarming frequency in the modern world – and the associated death toll reflects this. Indeed, the Derna Dam collapses do not stand in isolation. Other major dam collapses have occurred this year at the Kakhovka Dam in Ukraine and the Braskereidfoss Dam in Norway (Canadian Broadcasting Corporation, 2023; Stone, 2024). Certainly, dams are designed and engineered to withstand worst-case conditions, like heavy rains, to prevent any sort of structural failure. But what happens when what was once considered to be a once-in-a-century weather event occurs with increasing frequency? In such cases, the sudden onslaught of millions of cubic meters of water is potentially leads to emergency states. 

Space-based technologies and disaster management 

Space-based technologies are being increasingly incorporated into disaster management approaches, both before the potential disaster occurs and afterwards. Perhaps one of the biggest benefits of space-based technologies, as opposed to terrestrial technologies, is the sheer scale with which they can operate. Particularly, when it comes to monitoring natural disasters, satellites can provide a unique vantage point of Earth that is appropriately zoomed-out. Before a disaster occurs, satellite imagery allows us to recognize storms forming over the ocean and track their progress from a safe distance. As a result, countries that fall within the predicted path of a storm are afforded the luxury of time regarding disaster preparedness. Space-based technologies are also important in the aftermath of a disaster. In the case of Derna, maps and data sets have been developed to show which buildings and households were washed away and which were left intact. Rescue workers are therefore able to estimate how many people may be missing or injured and therefore tailor their rescue efforts accordingly. Two applications of space-based technologies will be outlined below: early warning systems (pre-disaster) and damage recognition maps (post-disaster). 

What does it take to avoid a disaster? Early warning systems can inform and alert people of impending storms – all before any damage occurs. When utilized effectively, they can greatly limit economic losses, save lives, and reduce human suffering. Effective early warning systems are complex systems that must coordinate a multitude of actors and actions, such as storm forecasting and prediction, hazard monitoring, an appropriate response plan, and a communication plan (Figure 13). Space technologies contribute to this through remote sensing of atmospheric conditions over land and oceans allowing scientists to determine where a storm might be forming, how strong it might be, and where it might be heading (Maniewicz, 2023). For example, the Atmospheric Infrared Sounder on NASA's Aqua satellite uses infrared technology to create 3D maps of air and surface temperatures, water vapor and cloud properties. Scientists use the data to create vertical profiles of atmospheric temperature and moisture, greatly helping to predict when and where storms might form (Conway, 2022). 

Considering the Derna floods, it is important to note that Libya’s National Meteorological Center detected incoming problems and did issue an early warning for Storm Daniel. This was sent to all governmental authorities 72 hours in advance of the storm and resulted in a state of emergency being called. Their models suggested unprecedented levels of rainfall and floods, all of which did occur (World Meteorological Organization, 2023b). Unfortunately, the early warning system did not incorporate the risk posed by the aging dams which ultimately caused far greater flooding than the rain itself. This demonstrates an inherent flaw in many early warning systems: the need to be attuned to the hazards of a specific community. Incorporating dam infrastructure into early warning systems is an emerging field and advancements are being made. However, this also adds a layer of anticipated complexity that may or may not be reasonable for communities already stretched thinly for personnel and expertise in this field (United Nations, 2023).

Once a disaster has already happened, it is critical to know how many people may be missing or injured, and where they are likely to be. This information is particularly helpful in massive flooding events, such as in Libya, where entire neighbourhoods were washed out to sea displacing thousands of people (Figure 14). To solve this, scientists can compare satellite imagery from both before the flood and after the flood to create a dataset that demonstrates building intactness. One such data set, known as Open Buildings, has been produced for the city of Derna. In essence, the map shows building footprints from before the flood overlain on top of satellite imagery from post-flood, demonstrating which buildings were washed away (Figure 15). Having this data provides clues as to what the population size and density was within a given region, allowing experts to estimate how many people may be missing based on the level of destruction. Beyond this, it also provides the knowledge of which areas require the most attention. Aid workers are therefore able to tailor their efforts to serve the areas that are most in need of help. The map and dataset can be found here: https://open-data.gishub.org/libya_buildings/

A second crisis – the risk of waterborne disease 

There remain significant health risks facing the survivors of the Libyan flood due to contaminated water sources, as well as insufficient access to sanitation and hygiene facilities. The lack of access to clean drinking water increases the probability of contracting water-borne diseases, such as diarrhea and cholera. Normally, drinking water in this region is provided by a desalination plant, known as the Derna Desalination Plant. Storm Daniel, however, caused significant damage to the facility, forcing it out of commission for nearly a month. This resulted in thousands of people being without a source of clean drinking water in the immediate wake of the flood, ultimately contributing to 4,464 cases of acute diarrhea (NCDC, 2023). 

In the subsequent days and weeks after the two dam collapses, neighbouring cities and international aid teams supplied as many water trucks and as much bottled water as possible to city residents. Although Derna city officials advised to only consume bottled water, in many cases, this was not possible due to issues of scarcity and affordability. There are several reports of limited bottled water availability, particularly as the immediate rush of aid has dwindled since the flood (WHO, 2023a). Water prices have also reportedly increased, with many flood survivors struggling to afford the now inflated price of bottled water (IFRC, 2023). As a result, we are witnessing a disparity form amongst the flood survivors - those who can afford to drink clean water and those who cannot. There remains a clear underlying need for subsidized water costs to those affected, as well as an increased distribution of water to remote areas.

For those who cannot afford or obtain bottled water, there remain few options but to drink whatever water one can find for survival. Much of the environmental water in the area, however, is deeply contaminated. Water contamination can occur in many ways, such as contamination from salt, chemicals, viruses, bacteria, or debris. Pathogen pollution is of particular concern in this case, given that many sewerage systems were destroyed by the flood. Many regions of Derna rely strictly on pit latrines, which were washed into the environment, along with their contents, during the flood. Paul Hunter, an infectious disease specialist at the University of East Anglia, spoke on the risks of floods and water-borne diseases: “All the [faeces] in the pit latrines gets washed out. If people drink that water, because there’s no other water, and they cannot sterilise it, they can pick up illnesses” (Bardsley, 2023). Compounding this is the reality that, with sanitation facilities and sewage systems having been washed away in the flood, the risk fecal contamination in the environment is high. UNOCHA has gone on to state that the rebuilding of sanitation and waste facilities must be a key area of focus: that “immediate priority needs for early recovery include the rehabilitation of water and sewage infrastructure, as well as waste management” (UNOCHA, 2023).

Another critical aspect of health in the wake of disaster relates to water, hygiene, and overcrowding. The Libyan flood damaged hundreds of homes, displacing an estimated 45,000 people (UNOCHA, 2023). As a result, flood-survivors have largely congregated in camps, settlements, and near the outskirts of town in the remaining undestroyed homes. The sudden influx of tens of thousands of people, however, creates overcrowded shelters and heightens the risk of disease in such areas (Figure 16). This includes diseases related to hygiene, such as diarrhoeal diseases, as well as the transmission rate of diseases such as measles and other infections that spread from person to person (Hammer et al., 2018). Without access to handwashing facilities, sufficient soap, showers and bathing facilities, or adequate sanitation facilities and latrines, there is a documented increase in communicable diseases within communities after a major flood. To learn more about how space technology can help WASH in informal settlements, read this article.

In addition to the risk of water-borne diseases, there is also a longer-term threat of vector-borne diseases as well. The dam collapses released massive quantities of water into the environment, creating an unprecedented number of pools of stagnant water within the region. Certain vectors, such as mosquitoes and flies, require such conditions to proliferate. Read more about space-based predictions of mosquito outbreaks in this article. This may yet create a “boom” of certain vector-borne diseases in the immediate future, such as malaria, yellow fever, typhoid fever etc. (WHO, 2023c). For example, there is a reported lag time of approximately 6-8 weeks before the onset of a malaria epidemic in malaria-endemic countries after a significant flood (WHO, 2005). Within Libya, the amount of stagnant water has been recorded to be particularly high in the regions of Al-Makhili, Derna, and Soussa, potentially creating an epidemiological challenge that could persist in the years to come (WHO, 2023c).

Finally, it is important to note that, while all these issues are serious threats on their own, there is a compounding problem of disrupted health care services in the region. There have been challenges regarding the treatment of those sick and injured, as well as in the distribution of vaccines. One month after the disaster, the WHO assessed the functionality of public health care facilities in the region. This included 231 facilities in total (including a primary, secondary, and tertiary health care facilities). Of these facilities, only approximately 15% of them were fully functional, meaning that 85% of them were partially functional or non-functional (Figure 17) (WHO, 2023c). The partial or non-functioning facilities experienced issues due to damaged infrastructure and shortages of staff, medicine, and supplies. In particular, the loss of over 100 health care workers to the floods has challenged the already-depleted staffing within Libya's health facilities (IFRC, 2023). The disruption of health care services is being felt by the most vulnerable groups, such as those injured or displaced by Storm Daniel, children, women, and patients with chronic disease. It is unclear how long it will take for infrastructure to be rebuilt and for normal health care services to resume, but it is likely that the ramifications of this disruption in health care services will be felt for decades to come. 

Conclusion

The scale of disaster that occurred in Libya is monumental. With entire swathes of neighbourhoods washed out to sea and an estimated 8500 people still missing as of late November 2023, it is hard to know when or if survivors will be reunited with their loved ones (International Organization for Migration, 2023). It is important to understand that a disaster such this is multifaceted, with many contributing factors to such high levels of destruction. The impact of climate change on storm frequency and intensity cannot be overlooked or overstated. The evidence is clear – there is a high-risk of increased storm severity in our ever-warming world. At the same time, we must understand the impact of political instability on critical infrastructure, particularly when it comes to high-risk structures such as dams or nuclear facilities. In the wake of floods in particular, survivors remain at elevated risk, notably as related to water-borne diseases. There is no simple answer. Indeed, there is no simple path forward. We are well beyond the state of simplicity in these times. We can remain hopeful, however, that as technologies continue to progress, more refined early warning systems will continue to be developed that will ameliorate future large-scale destruction from occurring.