Vietnamese media over the last few weeks has seen abundant coverage of land subsidence issues in the Mekong River Delta (Cuu Long Delta). There follow a series of national and regional events discussing the planning of this river delta in the face of growing exacerbation of climate change impacts. The repeated message is that, according to a new research (by Minderhoud et al, 2017), land subsidence is progressing at dangerous rate in many provinces in the delta, caused by overreliance on groundwater sources, and that this effect is much greater than that of climate change induced sea level rise. The combined impacts of these two processes are deemed to submerge the entire Cuu Long Delta in the course of the next 100 years (Dantri, 2017).
This is just one example from one region of Vietnam of the magnitude of disaster risks facing our cities, and our ability to reverse the onset of future urban disasters depends on an understanding of their nature.
Mind and chance
The first step to understanding urban disaster risks is perhaps to ask how the cities where they take place arrive at their current shape. Think of any major Vietnamese city of the modern day, say Da Nang City on the central coast, and most likely, the first images that pop up in your mind would be ones of magnificent bridges such as the Dragon Bridge and Tran Thi Ly Bridge on the Han River, of high-rising skyscrapers such as of the 37-storey City Administrative Hall and the also 37-storey Novotel Hotel nearby, of luxurious resorts such as those on along the coast on Truong Sa road, or of the city’s busy streets, shopping malls, markets, airport and amusement parks. All of these come together to make up an image of a modern city, shouting credit to the architects who first laid out their imagination on a piece of paper.
On the macro level, the ways these physical infrastructures and spaces are connected, the ways they interact with one another to enable the flows of goods and services, water and money, people and ideas are orchestrated by higher level designs, written in the city’s development plans, strategies, regulations and policies.
Da Nang’s urban master plan prescribes which areas of the city are to see more apartment buildings and service facilities, which to be reserved for agriculture production, ecological tourism and green parks, which to be raised to which elevation and which are to be kept unchanged, the density of population, buildings, transport network, the installation of utilities and emergency facilities, and the locations of industrial facilities. The city’s regulations and policies provide from the height limit of buildings, to the minimum size of drainage pipes and the technical requirements of construction. They also have implications on the kinds and amounts of capital investments, the freshness of the water and air, the flow of traffic, and the depth, frequency and duration of flooding in local neighbourhoods. Again, there are many minds behind each of these blueprint documents through which cites are structured, organized, and operated, and their different trade-offs are made.
Lastly, at the micro level, the urban spaces are also shaped by all city inhabitants, those who live and work there on the daily basis with their down-to-earth demands, and whose creation and imagination are expressed in every little corner of the city.
The three narratives above claim that the city is the product of the human mind and action. A city after all is where people decide to gather and together create the conditions to increase their comfort of living and their opportunity to exchange and grow.
However, the reality of urban development is never exactly what was originally written or thought up. The actual shape of the city often diverges largely from what was prescribed in the blueprints, not only depending on how robust these blueprints are, or how strictly their implementation is enforced, but also on the uncertainty nature of everyday life in the city.
On the other hand, there is another part to the city’s landscape, one which runs hidden below every building’s foundation, and which had been there before the first brick of the city was laid—it is the underlying landscape that the city is built upon.
Can Tho city of the Cuu Long River Delta originates and develops on the background of a crisscross network of rivers and channels. It is the flow of these rivers and channels that moulded the shape of the city’s urban landscape. The first people of Can Tho grew their crops in the delta fields enriched by the rivers’ abundant sediment flow, and built houses close to the rivers for better access to water, trade and travel. Houses, markets, pagodas, and then parks, schools, hospitals, banks, and shopping malls find themselves meander with the flow of the Hau River, the Can Tho River and countless number of small rivers and channels here. In this way, the blueprint of Can Tho City was first drawn by nature, not the human mind.
Although these natural blueprints might not always be directly visible, but hidden behind or altered greatly by newly established urban infrastructures, they played a critical role in the forming of today’s modern cities. Perhaps the city cannot exist and prosper without the pre-laidout work of nature or the imagination and labour of humans. As Italo Calvino put it (in Invisible Cities), ‘Cities also believe they are the work of the mind or of chance, but neither the one nor the other suffices to hold up their walls.’
Every city is subject to its unique geological and climatic conditions. It might be the dominance of favourable and the overlooking of unfavourable conditions that put a city at a specific location in the first place, but exposure to natural disasters exists for all cities, and has been evolving with natural processes and human interventions.
Da Nang is a coastal city, with the Da Nang seaport being a critical hub for exchange and trade throughout its history and bringing wealth to the city. However, this position also exposes Da Nang to the numerous storms and typhoons from the East Sea. Every year, Da Nang experiences the direct impact of about one tropical depression or storm, and the average annual precipitation of the city typically range from 2000 to 2700 mm (ACCCRN, 2009). To the west and northwest of the city are mountain ranges and hilly lands, which are the source of various rivers that flow downstream where the city centre is. Higher than average precipitation in mountainous areas combined with the short and steep river system leads to the high risk of flash floods. The mountains and rivers and winds had been there long before Da Nang was built. As more and more urban structures are erected, more and more spaces of natural ecosystems are taken over, and more and more natural process are interfered with. Failure to offset the counter effect of these interferences increased the city’s exposure to a wide range of natural hazards, including floods, inundation, riverbank and coastal erosion, droughts, and saline intrusion (ACCCRN, 2009).
However, exposure to natural hazards only makes up a half the disaster risk equation in cities. The other half is vulnerability, which is the likelihood of experiencing damaging impacts of natural hazard events (Wisner et al, 2004), and is generated through a predominantly social process. Decision-making and policy making in the cities happen on an uneven field. Many groups of people in the city only have nominal influence over city planning and construction. It is also in the urban master plan and the different regulations and policies of cities that the risk profiles of different demographic groups and areas are laid out.
The Nguyen Van Cu Road in Can Tho was renovated into a 34 m wide, and over 2.3 m high road by the end of 2014 to boost urban mobility and economic growth. The areas of An Khanh 1 and An Khanh 2 & 3 lie across each other by this road. According to the approved detailed plan, An Khanh 1 was to be developed into a highly urbanized area with commercial and residential blocks. With large investments from developers, the area was soon raised to the elevation of 2.2 m, for the development, and thus freeing it from most flooding troubles. Meanwhile, on the other side of the road, An Khanh 2 & 3, a low-lying agriculture area which did not receive as much interest from private and public investors, was slow to have its plan implemented, and gradually became a check board of varying elevations due to poorly regulated autonomous development. Any area that remained undeveloped and trapped by surrounding elevated roads and buildings was quick to get inundated following rainfall and high tide events (Nguyen et al, 2016).
The tales of these two neighbourhoods in Can Tho revealed the tremendous effect good and bad planning and implementation and rule enforcement can have on the vulnerability of city habitants. Through the planning and implementation process, the risk profiles of the two neighbourhoods were completely altered—risks were released for the people who had enough resources to put themselves on higher grounds, and created or worsened for the people who did not.
On another account, in today’s inter-connected municipalities, disasters risks are not only generated locally but also regionally and globally. The regional dynamic of disaster risk creation, for example, can be seen in the numerous cases of cross-boundary watershed management throughout Vietnam. One of the 10 largest water basin in Vietnam, the Vu Gia – Thu Bon River Basin which covers Quang Nam Province and Da Nang city is struggling with conflicts over the management of hydropower reservoirs upstream of the river system in Quang Nam, which has impacts on water scarcity and flooding issues downstream (MacClune, 2017).
At the global scale, climate change has been playing a growing part in incubating the trigger events of disasters in the world’s cities. Climate change arises from both the natural and the anthropogenic process, however it is strongly believed by scientist that the anthropogenic effect predominates the natural one (IPCC, 2014). The intensification of tropical storms and hurricanes, their more and more frequent visits (evident in the recent series of super-hurricanes battering Caribbean islands and US coasts), the increased variability and unseasonableness of temperature and rainfall patterns all undermine people’s ability to predict and respond. A global phenomenon, climate change roots itself from overwhelmingly national and global policies, thus the people in Vietnamese cities are suffering more climate change risks due to policies made mostly elsewhere in the planet.
Locally or globally, the disasters of the city are already written in its natural, and in a more and more predominant way, human-cast blueprints.
To escape the inferno
If it is mostly the mind and action of humans that registered disaster risks into the structure of the city, then through changing the mind and the action maybe these disaster risks can be written off. ‘There are two ways to escape suffering it,’ Italo Calvino said, ‘[t]he first is easy for many: accept the inferno and become such a part of it that you can no longer see it. The second is risky and demands constant vigilance and apprehension: seek and learn to recognize who and what, in the midst of inferno, are not inferno, then make them endure, give them space.’
For all the hazards that are sure to come, we had better acknowledge their threats and be prepared. This is what people in central coastal cities of Vietnam had in their minds about the river floods that they have to face year after year. ‘Living with floods’ has always been their way of living for generations. A case study in Quy Nhon (DiGregorio & Huynh, 2012) described the way generations adapt to flooding in this city:
Accepting that floods are coming, people set up small-scale earthen banks, sandwiched in between lines of bamboos, to protect the river banks and ease the damage to their properties in case of floods. Being artisanal and strategically placed, these bamboo dykes allowed floodwater to gradually drain towards the large Thi Nai lagoon east of the city. Accepting that floods are coming, people adapt their agriculture calendar to the flood season. They regard seasonal floods as a natural source of fertilizer and pest propellant, and organize cultivation, salt making and aquaculture activities around them. Accepting that waters are coming into their houses, people build houses with a loft area close to the roof where their family members, together with the food supplies and household valuables, can take refuge from the rising water.
Traditional ways of failing safely and submitting to the cycle of nature proved to be robust adaptions to hazards, helping to boost their resilience to the potentially disastrous impacts of these events.
Make them endure, give them space
Further forward to the modern day’s cities, the more unnatural natural hazards and disasters have come to be. They tend more and more to be created rather than pre-existing, and thus can no longer be accepted, hence (my reading of) Italo Calvino’s advise to learn about their roots: to identify who, or the vulnerable victims of the disasters (whom to make endure); and what, or the features of the city that can help to reverse the creation process (which to give space to).
People living downstream of the Vu Gia – Thu Bon river system in Quang Nam province and Da Nang City, in a similar way with people in Quy Nhon city as describe above, were well adapt to the rising annual floods from these rivers. However, recent urban development and hydropower development upstream of the river basin brought about major changes in the pattern of flooding, rendering floods to be much less predictable and causing critical disruptions to local life downstream. ISET, with the support of CARE International experts, are conducting vulnerability assessment in five communities in Quang Nam and Da Nang with the focus on these matters. The case studies seeks understanding of the way these local communities, especially children, the elderly, women, and people with disability, have become more vulnerable because of the altered hydrological regimes of rivers in the Vu Gia – Thu Bon system. This understanding provides a starting point for the dialogue between Quang Nam and Da Nang, and for the formulation of needed policy change to reduce this vulnerability (Nguyen, 2017).
An example of the what, Can Tho city, as mentioned previously, was developed on a network of rivers, channels and canals. As urbanization proceeds here, however, these flowing water bodies kept shrinking—drainage channels filled or covered, and riverbank areas encroached—and became more and more polluted (Nguyen & Tyler, 2017). In addition, a recent research (Minderhoud et al, 2017) claimed that subsidence in Can Tho was as much as 20 cm over the period from 1991 to 2016 due to overexploitation of groundwater. This means that subsidence is causing the city to sink at a much higher rate than sea level rise, which is only about 3 mm/year in the Cuu Long Delta, and posing higher threats to the city’s residents related to flooding and saline intrusion. In order to reverse this trend, Can Tho needs robust policies to protect, restore and revive its rivers and channels, and to stop the exploitation of its underground aquifers, return these water bodies their deserving space in the city.
Every city today wears the traces of all the cities that came before it, their earlier versions that date back thousands of years. These shadow cities might be subtly hidden away most of the time, but become strikingly visible every time the next disaster hits the city. At the same time, for every city that exists today, there are also a countless number of cities that could be, and with our thoughts and actions now, we are writing them into being.
Tho Nguyen, ISET-Vietnam
 The current master plan of Da Nang is until 2030 with vision to 2050, and its latest updates were made and approved in December 2013 (Decision no. 2357/QĐ-TTg dated December 04, 2013).
 Read more on disaster risk creation in Kelman (2012).
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