Category Archives: Flooding

Flooding Death Toll Tops 100


Fishermen take advantage of the flooding in Prey Veng province on Wednesday. SRENG MENG SRUN

Flooding death toll tops 100

Thu, 10 October 2013

The death toll from flooding that has affected nearly all of Cambodia has hit 104, the National Committee of Disaster Management said yesterday. With more than 60,000 people having been evacuated, relief agencies are raising concerns over disease outbreak.

The most heavily hit province was Kampong Cham, where 26 people alone have died from flooding, NCDM vice chairman Nhim Vanda said.

“Now, we’ve completely tallied the reports from local authorities and can confirm that 104 people have died,” he said.

A report by the Humanitarian Response Forum released on Monday expressed concern over insufficient sanitation and water in evacuated areas where the risk is high of disease outbreak and contaminated food.

Yesterday, 600 families were evacuated from the Banan district in Battambang before water released from the Kampong Pouy basin caused a flash flood, Buth Sambo, a police chief of Banan district, said. He denied rumors that the Kampong Pouy basin was broken or collapsing.

In Banteay Meanchey, 19 military doctors have been sent by the Defence Ministry to treat more than 500 families evacuated in Poipet town, Deputy District Governor Men Sophan said.

Though water has inundated the halls and reaches up to a metre high outside the Banteay Meanchey Provincial Prison complex, prison authorities have taken no steps to evacuate inmates.

The prison is known to flood every year, but rights organisations are calling this flooding the worst seen since the detention centre opened in 2009.

“We have not taken any moves to evacuate the prisoners, because we can control the situation,” Banteay Meanchey prison director Hin Sophal said. “The water is creeping into the staff rooms, but it cannot go to the prisoners’ rooms.”

According to rights groups, with the building flooded, prisoners are not able to leave their overcrowded cells, leading to numerous sanitation and mental health concerns.

“We are concerned that if the water continues rising, the authorities will have to evacuate the prisoners to somewhere.…They are humans, not rocks …so they can escape when evacuated,” Som Chankear, provincial coordinator for Adhoc, said.

Though the Ministry of Interior has said it plans to prevent the cells from flooding through sandbag banks and continuous water pumping, neither the ministry nor the prison had an idea of where the prisoners could be taken if necessary.

“It is normal, and where the prisoners stay is safe,” Kuy Bun Sorn, director general of the department of prisons in the Ministry of Interior, said.


Sewage Canal Bursts Its Banks


A coconut seller walks in ankle-high floodwater from an overflowing sewage canal yesterday in Phnom Penh’s Chamkarmon district. VIREAK MAI

Sewage canal bursts its banks

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Thu, 10 October 2013

Raw sewage spewed onto Street 105 from the antiquated discharge canal running parallel to it yesterday as heavy rains continued to create headaches in the capital.

The putrid water lipped homes and local business on the street in Chamkarmon’s Boeung Trabek commune, alarming residents.

Pich Panha, 20, a local resident living about 17 metres from the open sewage canal, said the water had been steadily rising for two days.

“We’re worried about getting dengue fever [from the mounting sitting water] so we’re trying to be extra careful,” Pich Panha said, against a backdrop of thigh-high sewage water brimming with floating trash and discarded bottles.

The city was pelted with heavy rain that began at about 3pm on Tuesday and continued until around 5:30pm, according to Touch Meas Snguon, a 38-year-old motorbike taxi driver renting a room dangerously close to the odorous overflow.

“I could not make money today. My motorbike is broken after I drove it through the water last night,” Snguon said.

But Snguon noted that locals were accustomed to living around wastewater and rarely got sick, while repeatedly emphasising it was rainwater, not sewage, seeping onto the street.

Water levels at Boeung Trabek Pumping Station hit six metres on Monday night following heavy rain, up from the normal 3.6-metre mark, 71-year-old Em Sothat, an employee at the station, said.

“We usually use only three machines to pump water, but since Tuesday night, five more machines have been used,” Sothat said, adding that the water hit peak levels this year during Tuesday’s downpour.

Togo Uchida, a project formulation adviser in charge of environment and climate change at the Japan International Cooperation Agency (JICA), said the organisation has been working with City Hall since 1999 to repair and expand the city’s existing drainage system.

“What I’ve heard unofficially is the pumping system [connected to Boeung Trabek Pumping Station] is manned by eight pipes. The issue with the open sewage channel, one which City Hall has been working to improve for many years, is maintaining the channel’s cleanliness,” Uchida said.

Wastewater travels through Phnom Penh’s central piping through the open canals to Boeung Trabek.

It is then partially purified by morning glory and lotus growing in waters north of the station. Chreang Sophan, a deputy governor in the capital, cited climate change and a rapidly growing urban population as among the blockades slowing repair of citywide drainage systems.

“The population is growing very fast, [faster than] most of our drainage systems have expanded,” Sophan said.

Both Uchida and Sophan highlighted how skyrocketing urban development is outpacing expansion of the city’s drainage system, a key component in City Hall and JICA’s frequently criticised execution of the project.

Contact authors: Phak Seangly and Amelia Woodside

Flooding in Phnom Penh Nears Emergency Level


By Ben Sokhean and Simon Henderson – September 30, 2013

Almost 8,000 families have now been evacuated to higher ground since severe flooding across the country began two weeks ago and two more children were confirmed to have drowned over the weekend bringing the nationwide death toll to at least 28, officials said.

In Phnom Penh, where floodwaters on Sunday were inching closer to emergency level, 161 families have been evacuated from Meanchey district since Friday with thousands still grappling with inundated homes and poor sanitation.

Kao Sareth, 65, prepares food in his flooded home in Phnom Penh's Meanchey district on Sunday. More than 160 families in Meanchey district have been evacuated from their homes since flooding hit Friday. (Siv Channa)

Kao Sareth, 65, prepares food in his flooded home in Phnom Penh’s Meanchey district on Sunday. More than 160 families in Meanchey district have been evacuated from their homes since flooding hit Friday. (Siv Channa)

Keo Vy, deputy director of information at the National Committee for Disaster Management, said that the two young victims died on Saturday in Kompong Cham province, where thousands of families have been evacuated to higher ground.

“Two children died by drowning on Saturday in Kompong Cham. A 6-year-old boy drowned in Batheay district’s Sambour commune, and a 2-year-old girl also died by drowning in Kroch Chhmar district, Trea commune,” he said.

“At least 28 people have died due to flooding in the past two weeks including 16 children, which brings the total killed in floods to 41 so far this year,” Mr. Vy said.

Across the country, a total of 7,897 families have been evacuated, 62,036 houses have been flooded, and 73,616 families nationwide have been affected by the floodwaters, he said.

The Mekong on Sunday rose 14 centimeters at the Tonle Bassac-Chaktomuk water station on Phnom Penh’s riverside to reach 10.2 meters, just below the 10.5-meter emergency level.

Mr. Vy said authorities were concerned that the water levels would rise further in the coming days.

“We are worried about Phnom Penh now because on Saturday the water level reached 10.2 me­ters and may soon reach the emergency level,” he said.

Along the banks of the Tonle Bassac in Chbar Ampov II commune, families waded through muddy meter-high water that has inundated their homes since the river broke its banks last week. Some villagers have erected make­shift wooden walkways and children were using rubber ding­hies made from tire tubing to travel through the increasingly fetid floodwaters.

Though many have already been moved to a nearby safety area, hundreds more continue to cook, eat and sleep in corrugated huts waist-deep in water, leading to dangerous conditions for many young children in the area.

“The water is up to my stomach in my house and nobody has come to help me,” said Chea Narin, a 50-year-old community leader in the commune.

“Some people have no working toilets so they are using the water, and it has brought a really bad smell and my children have had diarrhea. It is hard to keep the children in the house all the time, so they play in the water but we are afraid they will drown like in other provinces,” he said.

Mr. Narin works at a timber yard across what used to be the road in front of his house, but the warehouse floor is under water and the timber is soaked through bringing work to a standstill.

“We need the Red Cross, NGOs or the authorities to help us because we cannot work so have no money to buy food or clean water—all the families here are affected,” he said.

Further upstream in Chraing Bak village, 32-year-old Yoeng Yeung, an ethnic Vietnamese construction worker, said that his house has been completely flooded for about a week and he was worried about his two children.

“Under my house the floodwater is 1.5 meters deep so it is really difficult—inside the house the floor is submerged so I can’t cook or use the toilet,” he said.

He gestured to his two young children who stood behind him on the small makeshift bridge and said that he was frightened that they will drown because they cannot swim.

“Neither the Cambodian Red Cross nor any NGOs have come to help us yet,” he said, adding that despite the floods he must still go to work, while his wife stays home to care for the children.

Yen Vuth, Chbar Ampov II commune chief, said that more than 60 families have been evacuated to a safety area in Doeum Sleng I village over the weekend with more than 1,000 families along the river were currently affected by the floods.

City Hall spokesman Long Dimanche said that more than 160 families had already been evacuated to higher ground in the capital’s Meanchey and Rus­sei Keo districts.

“Municipal authorities have received a directive from the government regarding flooding in the city and we are now preparing to provide the affected families in the areas with assistance.”

Stung Treng, Kratie, Kompong Thom, Kompong Cham, Kandal, Banteay Meanchey, Oddar Meanchey and Preah Vihear provinces have experienced the worst of the flooding over the past two weeks, but heavy rainfall from tropical storm Wutip, which made landfall in Laos from the South China Sea on Friday, has extended the reach of the flooding, with Phnom Penh and also Prey Veng province receiving new warnings.

Chann Tha, Prey Veng province’s director of administration, said that emergency level had been declared Sunday when floodwaters reached 7.5 meters.

“Seven districts in Prey Veng province have been affected now by flooding and we evacuated 295 families to higher ground on Saturday and Sunday, while 10,414 houses have been swamped by water,” he said.

Health officials across the country have expressed concern that the flooding could cause a health crisis as a shortage of clean water for drinking and washing is leading to outbreaks of diarrhea.

Cambodian Red Cross spokeswoman Men Neary Sopheak said Sunday that relief efforts nationwide were already underway, though she said she did not know when people living in flooded areas in Phnom Penh would receive assistance.

According to Ms. Sopheak, Queen Mother Norodom Moni­neath on Saturday donated $10,000 to the Red Cross to help with the ongoing relief effort.

Related Stories Two More Die in Flooding, Aid Response Slow in Phnom Penh

Mekong River Flooding Threatens Parts Of Phnom Penh


Screen Shot 2013-09-28 at 6.30.24 PM Screen Shot 2013-09-28 at 6.30.40 PM


By  and  – September 28, 2013

Phnom Penh will face flooding in certain areas in the coming days as the level of the Mekong River surpasses emergency level, while heavy rainfall from tropical storm Wutip, which made landfall in Laos from the South China Sea on Friday, prompted the government to release new flood warnings for 11 provinces.

Forty-eight families were evacuated from their homes in Phnom Penh’s Meanchey district on Friday after floodwaters inundated their homes in Chbar Ampov II commune, municipal spokesman Long Dimanche said.

“Water from the river has started flowing into parts of Phnom Penh,” he said.

“Of course, we are concerned over flooding in Phnom Penh,” Mr. Dimanche said, adding that city officials have prepared sandbags to staunch floodwaters in low-lying areas of the city.

On Friday, the Mekong River reached 10.06 meters at the Tonle Bassac-Chaktomuk water station on the city’s riverfront, just below the emergency 10.50-meter level, stirring concerns of further flooding in three districts: Meanchey, Dangkao and Pur Senchey.

“We are ready to help evacuate and rescue Phnom Penh residents in three possible flooded districts,” Mr. Dimanche said.

The Ministry of Water Resources and Meteorology said in a statement on Thursday that tropical storm Wutip would bring heavy rains between Saturday and Tues­day to most of the country, and coastal fisherman were advised to stay on land until Wednesday.

“The rainfall mentioned will cause Mekong River flooding again,” the ministry said in the statement, which also called on authorities in affected areas to respond to people’s needs in order to avoid loss of life.

The death of a mother and her two young children on Thursday brought to 39 the number of people killed so far by flooding, which has forced almost 6,000 families from their homes and flooded a further 30,000 residences in eight affected provinces: Stung Treng, Kratie, Kompong Thom, Kompong Cham, Kandal, Banteay Mean­chey, Oddar Meanchey and Preah Vihear.

In Ratanakkiri province, 24-year-old Srey Noy died along with her two sons, 2 and 4 years old, when the motorcycle on which they were traveling drove into a deep ditch that was submerged by flash floods in Kon Mon district’s Ta Ong commune. Three more people drowned Friday, two in Kratie and one in Kompong Cham, said Keo Vy, deputy director of the information department at the National Committee for Disaster Management.

In Kratie province, flooding from the Mekong River cut off access to some 30 km of National Route 73 between Chhlong district and Kratie City on Wednesday, and on Thurs­day, flooding closed off Road 371 between Chhlong and Kompong Cham province, said Sreng Sros, deputy director of the Kratie provincial department of public works and transportation. Both routes are under 30 cm of water. A 500-meter stretch of Road 377 in Kratie’s Sambor district has also been impassable since last weekend but motorists heading to the northeast can still travel between Kompong Cham and Kratie via National Route 7, Mr. Sros said.

Khoy Khunnhor, chief of cabinet of Preah Vihear province, said that the province declared an emergency on Friday when the Stung Sen River reached 11.76 meters, far above the emergency level of 10.50 meters.

“Three districts and the provincial capital in Preah Vihear province have been affected by flooding,” said Mr. Khunnhor, adding that hundreds of families have been evacuated to higher ground.

“We told the people near the river to be highly careful of flooding.”

Flooding’s Toll Still Growing


Villagers in Ratanakkiri province’s O’Chum district stand behind a collapsed bridge as floodwaters in the region swelled last week. PHOTO SUPPLIED

Flooding’s toll still growing

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Mon, 23 September 2013

Nearly 2,000 families have been evacuated from their homes and thousands of hectares of crops flooded in the wake of continuing rains and the opening of dams in Vietnam and Thailand.

At least two people have died since Friday in the flooding, which has affected at least six provinces.

In Stung Treng province, 1,597 families have been evacuated to higher land, Duon Pov, director of the provincial administration hall, said yesterday. Separately, at least 3,400 hectares of rice and several hundred hectares of other crops have been flooded in four districts, Touch Thea, director of the Stung Treng provincial agriculture department, said.

“The agro-industrial crops such as cassava may be destroyed, because they have been flooded for a few days. Whereas it is not yet known if the rice has been destroyed [or just damaged],” he said.

In Thailand, the opening of dams led to heavy flooding in three villages in O’Beichoan commune in Banteay Meanchey’s O’Chrou district, said district administrative police chief Chhun Sorngly. More than 300 families have been moved to safer areas since Friday, he said.

“Water got stuck in Thailand, and they opened the floodgates, which caused serious flooding on Friday and Saturday. People had to be evacuated and their hoofed animals had to be tied along the roads,” he said.

Authorities used three high-speed boats to evacuate people, he said, adding that no one had drowned as of yesterday.

Officials were now preparing for the expected opening of another flood gate in the coming days.

In Ratanakkiri, 73 families from Lumphat district were moved to four safe zones, said Deputy Provincial Governor Nab Bunheng.

“Last week, the Vietnamese authorities informed us to take precautions, because they opened a water gate,” he said.

O’Yadav District Governor Dork Sar said he already spoke with villagers about safety during the floods. On Sunday, a 25-year-old ethnic Jarai villager drowned while walking through a canal.

An estimated 1,000 families have been affected by the floods, but none have been evacuated in his district yet, Sar said.

More than 3,000 metres of roads were flooded in Oddar Meanchey and most of them are now impassable, officials said. But while 570 homes have been flooded, no evacuations have yet occurred.

“It is a flood due to rains on Friday and Saturday, not a flood from Thailand,” clarified Thon Nol, Samroang governor, adding that waters have begun to recede.

A 51-year-old was killed by electrical shock when walking through floodwaters in his home, Nol said.

In Kratie province, Chet Borey and Kratie town saw more than 1,000 people and thousands of cattle evacuated to higher ground, district police official Sao Kim Hort said.

100 Resilient Cities


“BUILDING RESILIENCE is about making people, communities and systems better prepared  to withstand catastrophic events – both natural and manmade – and able to bounce back more quickly and emerge stronger from these shocks and stresses. There’s no doubt: natural and manmade shocks and stresses will continue to hit the world’s cities. The cost of urban disasters in 2011 alone was estimated at over $380 billion. IT’S TIME FOR CITIES TO ACT.”


Learning to Bounce Back


By ANDREW ZOLLI Published: November 2, 2012

FOR decades, people who concern themselves with the world’s “wicked problems” — interconnected issues like environmental degradation, poverty, food security and climate change — have marched together under the banner of “sustainability”: the idea that with the right mix of incentives, technology substitutions and social change, humanity might finally achieve a lasting equilibrium with our planet, and with one another.

It’s an alluring and moral vision, and in a year that has brought us the single hottest month in recorded American history (July), a Midwestern drought that plunged more than half the country into a state of emergency, a heat wave across the eastern part of the country powerful enough to melt the tarmac below jetliners in Washington and the ravages of Hurricane Sandy, it would seem a pressing one, too.

Yet today, precisely because the world is so increasingly out of balance, the sustainability regime is being quietly challenged, not from without, but from within. Among a growing number of scientists, social innovators, community leaders, nongovernmental organizations, philanthropies, governments and corporations, a new dialogue is emerging around a new idea, resilience: how to help vulnerable people, organizations and systems persist, perhaps even thrive, amid unforeseeable disruptions. Where sustainability aims to put the world back into balance, resilience looks for ways to manage in an imbalanced world.

It’s a broad-spectrum agenda that, at one end, seeks to imbue our communities, institutions and infrastructure with greater flexibility, intelligence and responsiveness to extreme events and, at the other, centers on bolstering people’s psychological and physiological capacity to deal with high-stress circumstances.

For example, “resilience thinking” is starting to shape how urban planners in big cities think about updating antiquated infrastructure, much of which is robust in the face of normal threats like equipment failures but — as was just demonstrated in the New York region — fragile in the face of unanticipated shocks like flooding, pandemics, terrorism or energy shortages.

Combating those kinds of disruptions isn’t just about building higher walls — it’s about accommodating the waves. For extreme weather events, that means developing the kinds of infrastructure more commonly associated with the Army: temporary bridges that can be “inflated” or positioned across rivers when tunnels flood, for example, or wireless “mesh” networks and electrical microgrids that can compensate for exploding transformers.

We’ll also need to use nature itself as a form of “soft” infrastructure. Along the Gulf Coast, civic leaders have begun to take seriously the restoration of the wetlands that serve as a vital buffer against hurricanes. A future New York may be ringed with them too, as it was centuries ago.

Hurricane Sandy hit New York hardest right where it was most recently redeveloped: Lower Manhattan, which should have been the least vulnerable part of the island. But it was rebuilt to be “sustainable,” not resilient, said Jonathan Rose, an urban planner and developer.

“After 9/11, Lower Manhattan contained the largest collection of LEED-certified, green buildings in the world,” he said, referring to a rating program for eco-friendly design. “But that was answering only part of problem. The buildings were designed to generate lower environmental impacts, but not to respond to the impacts of the environment” — for example, by having redundant power systems.

The resilience frame speaks not just to how buildings weather storms but to how people weather them, too. Here, psychologists, sociologists and neuroscientists are uncovering a wide array of factors that make you more or less resilient than the person next to you: the reach of your social networks, the quality of your close relationships, your access to resources, your genes and health, your beliefs and habits of mind.

Based on these insights, these researchers have developed training regimens, rooted in contemplative practice, that are already helping first responders, emergency-room physicians and soldiers better manage periods of extreme stress and diminish the rates and severity of post-traumatic stress that can follow. Researchers at Emory University have shown that similar practices can bolster the psychological and physiological resilience of children in foster care. These tools will have to find their way into wider circulation, as we better prepare populations for the mental, and not just physical, dimensions of disruption.

There’s a third domain where resilience will be found, and that’s in big data and mobile services. Already, the United States Geological Survey is testing a system that ties its seismographs to Twitter; when the system detects an earthquake, it automatically begins scanning the social media service for posts from the affected area about fires and damages.

Similar systems have been used to scan blog postings and international news reports for the first signs of pandemics like SARS. And “hacktivists” are exploring ways to extend the power of the 311 system to help people not only better connect to government services, but also self-organize in a crisis.

In a reversal of our stereotypes about the flow of innovation, many of the most important resilience tools will come to us from developing countries, which have long had to contend with large disruptions and limited budgets. In Kenya, Kilimo Salama, an insurance program for small-hold farmers, uses wireless weather sensors to help farmers protect themselves financially against climate volatility. In India, Husk Power Systems converts agricultural waste into locally generated electricity for off-grid villages. And around the world, a service called Ushahidi empowers communities around the world to crowdsource information during a crisis using their mobile phones.

None of these is a permanent solution, and none roots out the underlying problems they address. But each helps a vulnerable community contend with the shocks that, especially at the margins of a society, can be devastating. In lieu of master plans, these approaches offer diverse tools and platforms that enable greater self-reliance, cooperation and creativity before, during and after a crisis.

As wise as this all may sound, a shift from sustainability to resilience leaves many old-school environmentalists and social activists feeling uneasy, as it smacks of adaptation, a word that is still taboo in many quarters. If we adapt to unwanted change, the reasoning goes, we give a pass to those responsible for putting us in this mess in the first place, and we lose the moral authority to pressure them to stop. Better, they argue, to mitigate the risk at the source.

In a perfect world, that’s surely true, just as it’s also true that the cheapest response to a catastrophe is to prevent it in the first place. But in this world, vulnerable people are already being affected by disruption. They need practical, if imperfect, adaptations now, if they are ever to get the just and moral future they deserve tomorrow.

Unfortunately, the sustainability movement’s politics, not to mention its marketing, have led to a popular misunderstanding: that a perfect, stasis-under-glass equilibrium is achievable. But the world doesn’t work that way: it exists in a constant disequilibrium — trying, failing, adapting, learning and evolving in endless cycles. Indeed, it’s the failures, when properly understood, that create the context for learning and growth. That’s why some of the most resilient places are, paradoxically, also the places that regularly experience modest disruptions: they carry the shared memory that things can go wrong.

“Resilience” takes this as a given and is commensurately humble. It doesn’t propose a single, fixed future. It assumes we don’t know exactly how things will unfold, that we’ll be surprised, that we’ll make mistakes along the way. It’s also open to learning from the extraordinary and widespread resilience of the natural world, including its human inhabitants, something that, counterintuitively, many proponents of sustainability have ignored.

That doesn’t mean there aren’t genuine bad guys and bad ideas at work, or that there aren’t things we should do to mitigate our risks. But we also have to acknowledge that the holy war against boogeymen hasn’t worked and isn’t likely to anytime soon. In its place, we need approaches that are both more pragmatic and more politically inclusive — rolling with the waves, instead of trying to stop the ocean.

Andrew Zolli, the executive director of PopTech, is the author, with Ann Marie Healy, of “Resilience: Why Things Bounce Back.”

Next City – 2011 Floods

This special issue of Forefront is part of The Rockefeller Foundation’s Informal City Dialogues, a year-long collaboration with Next City exploring stories and insights from six rapidly urbanizing cities around the world.

When the water started rising in October 2011, the ground snapped and squeaked as it broke into pieces. Bricks shattered, floor tiles cracked and water rushed up through the fissures. The deluge blindsided the 150 families living here, in a cluster of villages known as Kittiyarak nestled in Thailand’s Sai Noi district in Bangkok’s northwest suburbs. By the time the devastating flood receded some three months later, it would be on record as the worst natural disaster in modern Thai history.

“No one expected it to be this bad,” says Fongpol Konpruek, a 52-year-old former farmer from northern Thailand who moved to Sai Noi 16 years ago. “We were the first ones wet and the last ones dry.” Konpruek remembers the overwhelming confusion of those early days. “The water came from everywhere. It came slow, but it also came fast. I don’t know any other way to explain it.” Rising 20 to 30 centimeters per day until reaching a height of 1.5 meters, the debris-clogged tide submerged streets, sidewalks, parking lots and the ground floor of every building in the area.

What happened next says a lot about the power of social networks and informal systems in moments of urban crisis. Left with little official help, residents here — along with hundreds of thousands of people in other flood-struck parts of Bangkok — sprang into action. They quickly improvised a series of informal networks, and repurposed existing ones, to perform the vital tasks normally carried out by the government in emergencies. People with no training and few resources built barriers and monitored flood levels, delivered food and drinking water, evacuated residents trapped in their homes, provided medical services to the sick and injured, and policed their neighborhoods for looters. And when the water receded, these networks shifted focus and led a localized cleanup and rebuilding effort that helped the city rebound.

A child waits in the shade while workers harvest nearby in Sai Noi. These fields were inundated during the flood in 2011.

As cities around the world grapple with rising sea levels and strengthening storms, governments are responding with an array of infrastructural solutions. Since Hurricane Sandy, New York has increased the minimum elevation required for new and reconstructed buildings in flood-prone areas, and is raising subway entrances and ventilation grates off the ground. San Francisco is redesigning its water and sewage treatment system to the tune of $40 million to prevent rising sea waters from entering the pipes during storm surges. The Netherlands — nearly 60 percent of which is prone to flooding — is reimagining its entire coastal protection system, one of the most elaborate in the world, by allocating at least a billion euros annually to extend storm-surge barriers, relocate tidal channels, nourish beaches and increase the flood-protection levels of diked areas “by a factor of 10.” And for every mega-project like these, there are smaller, micro-targeted ones: The modest but growing Vietnamese city of Quy Nhon, for example, is spending $550,000 to restore 150 hectares of mangrove forests, helping to protect 14,000 households along its coast from strengthening monsoons.

But there’s also a growing awareness that combating disasters with hard infrastructure alone ignores half the equation. Perhaps just as important is a city’s social infrastructure. Recent research suggests that informal networks are critical to dealing with calamity and that areas with strong social cohesion fare better than areas where such networks are weak.

Bangkok isn’t the only place recognizing this. San Francisco’s Empowered Communities Program is working with local neighborhoods to increase their resilience in advance of disasters. The initiative supports communities as they develop action plans, but also generates higher levels of social capital among key stakeholders that can be invaluable during traumatic events. Participating groups include Neighborhood Emergency Response Teams (NERTs) and merchant associations. The city has even created a role-playing game called Resilientville that helps communities test and streamline their informal emergency response capabilities.

One of the most comprehensive efforts currently underway is in Wellington, New Zealand, where the largest unit of that city’s emergency management office is the Community Resilience Team (CRT). Dedicated solely to equipping and empowering informal networks to respond when disaster strikes, the CRT trains “Community-Driven Emergency Management” (CDEM) volunteers in how to promote preparedness among their own networks, as well as to respond as a community or plug into the official government response. Community response plans are facilitated by the CRTto guide planning at the local level to coordinate activities and manage resources like food and fuel. “Our whole model is getting normal people involved,” says Dan Neely, senior adviser for emergency preparedness at the Wellington Emergency Management Office. “People who are capable in their daily lives will be capable during an event. We’re trying to get to those people now… so that when a large-scale event happens, John Doe can tap into the wider community response plan.”

Wellington sent some of their CDEM volunteers to Christchurch when that city was devastated by an earthquake in 2011. But Neely emphasizes that you can’t just parachute in an informal response. “Part of this is building social capital,” he says. “We’re working to increase connectedness. Strong communities have better outcomes during a response.”

For evidence of this, look to Chicago, where informal networks played a major role in determining survival rates when a five-day heat wave killed 733 people in 1995. As Eric Klinenberg recently reported in The New Yorker, the neighborhoods that lost the fewest lives during that event weren’t necessarily the richest, but rather the ones that had especially strong social ties. His book Heat Wave documents the surprisingly high survival rate in the working-class Latino neighborhood of Little Village: “The social environment of Little Village protected not only the area’s Latino population, but the culturally or linguistically isolated white elderly, who were at high risk of death as well.” He points to the neighborhood’s “social contact, collective life and public engagement” as factors that “foster tight social networks among families and neighbors.” When crisis struck, those networks responded almost instinctually.

Such informal networks were critical lifelines for many in Bangkok in 2011, and as storms intensify and sea levels rise, they’ll only become that much more crucial. Cities everywhere are grasping the importance of such networks, but in many ways Bangkok has a head start — it’s a place where informality already infuses many aspects of everyday life. “The government is inefficient and corrupt,” says Bangkok-based engineering professor Visit Hirankitti, who is working on methods to enhance the city’s informal disaster response. But what Bangkok lacks in bureaucratic competence it makes up for in people-powered strength.

Ideally, a combination of capable government and robust informal networks, working in tandem, could provide the bulwark that cities will need in the age of climate change. This will require not only social cohesion, but a willingness on the part of governments to help equip communities for self-reliance and develop disaster plans that allow for a citizen-led response. There are signs that this is slowly occurring — from New York to Bangkok, recent events have forced cities to let informal networks react to disasters with relative autonomy. Whether they embrace a model in which private citizens and government agencies work in partnership could define their resilience as the coming storms arrive.

Saving Sai Noi

In Bangkok, informal networks are not only strong, they’re omnipresent. They have their roots in rural society and are intricately interwoven with the social fabric, even in urban areas. The greater metropolitan area has grown rapidly in the last several decades, doubling in size since 1980. In search of economic opportunities, migrants from the countryside have driven much of that growth. Despite the speed of this population expansion — or perhaps because of it — its residents have maintained strong social bonds. Such robust informal networks are also the product of a population that expects little of its government, aside from two revered institutions, the monarchy and the military.

Those networks attained new importance in late 2011, after Tropical Storm Nock-ten had made its way overland from Vietnam to Thailand in July. Over a period of weeks, rain from the storm, combined with heavy seasonal monsoons, overwhelmed the city’s dams. The Grand Palace was deluged, and Don Mueang Airport shut down after water flooded its runways. Panic gripped the city as the government declared a five-day emergency holiday. When all was said and done, 815 people were dead, 14 million were affected and over $45 billion in damage was left in the catastrophe’s wake, making it the fourth-most expensive natural disaster ever.

But in the days before the flood arrived, official channels of communication were strangely sanguine. The government urged Bangkok residents to stay calm, insisting there would be no emergency. As late as October 13, the Bangkok Post quoted the city’s governor, MR Sukhumbhand Paribatra, saying: “Right now, everything is under control. If we can’t control it, we will let people know straight away.” And even as the news media reported on the gigantic rain-fed pool growing ominously to the city’s north, they assured Bangkok’s residents that the water would never reach them.

Soon, however, dramatic images of the destruction of Southeast Asia’s second-largest economic powerhouse were swirling around the globe. But hardly anyone was looking at Sai Noi — not the media, and certainly not the government, which proved overwhelmed, unprepared and impotent in the face of a worst-case scenario. By late October 2011, the villages of Sai Noi were isolated and in dire straits.

A little over a year after the flood had receded, I hopped in a taxi one weekday morning and made the 45-minute drive from the gleaming shopping malls and high-rises of Bangkok’s central districts to the district of Sai Noi. I wanted to speak to residents there about how they had dealt with the flood, and how they’ll respond to the next big one, which nearly everyone is expecting someday soon.

Sai Noi is where booming New Bangkok collides with the rural customs and lagging economic growth of Old Thailand. In feel, it is neither urban nor rural. Instead, it’s a mishmash of the two, with rice fields and winding village lanes abutting the strip malls and multi-million-dollar commuter villas of Bangkok’s ever-expanding urban sprawl. It was areas like these, on the city’s north side, that were hit hardest by the flood and where the citizen networks were strongest. In part, they bore the brunt for geographic reasons, but also because the authorities decided to sacrifice them, releasing water into suburban areas in order to staunch the flooding in central Bangkok.

Vichain Kongsub, the elected chief of his village in Sai Noi. He and the local residents’ committee quickly improvised a plan when it became clear the flood would reach their area.

Surprisingly, there is little bitterness about this among the residents; their attitude is more like resigned acceptance. “It’s true that we were sacrificed, but not as badly as other areas,” says Vichain Kongsub, an affable man of 75 whose energy and trim build make him appear 20 years younger. “And anyway, what can you do? We had to suck it up.”

Vichain was at the center of Sai Noi’s informal flood-relief network. As the phu yai baan — which translates roughly as “village chief,” an elected, semi-official advisor found in nearly every community this size in Thailand — the people looked to him for direction. When it became obvious that the floodwaters would reach them, Vichain quickly called a meeting of the local residents’ committee, a nongovernmental body of 15 elders, to create an action plan for the community’s response.

Through consensus, the committee members decided how best to use the two resources the government had provided: Sandbags and a large water pump. “It was all very informal,” says Vichain. They organized residents into work crews — men shoveled sand and women carried the sandbags — and collected money from community members to buy a second water pump. The hope was, at least in these early stages, that they could stop the water from entering the villages. As it surged in, however, their defenses were overwhelmed. “We did our best,” says Vichain, “but it just didn’t work.”

Undeterred by this initial setback, the community found its stride as the situation worsened. Using a loudspeaker mounted on an electricity pole, Vichain and the residents’ committee organized a distribution network for food and water that was flowing into the area courtesy of a city-wide volunteer network formed by the television station Channel 3. Then, with the floodwater rising rapidly, they set into motion an orderly evacuation of residents. They selected six volunteers who would stay behind to monitor the situation and police the area for looters. All the while, this crew of volunteers was in touch with officials at the local sub-district government office by cell phone, to whom they provided updates, as well as the military, which was intermittently delivering aid to Sai Noi.

As one of the leaders of his village’s informal response network, Kritsada Rotcharatch was one of six people who stayed behind during the flood.

Kritsada Rotcharatch, a brash construction foreman who favors t-shirts with the sleeves cut off and carries a cell phone that rings constantly, was one of the six who volunteered to stay behind. He moved to the second floor of his house (the ground floor was underwater) where he kept an eye on property for his evacuated neighbors, who checked in regularly by phone. Kritsada armed himself with a gun for confrontations with looters. “There were no police. My role was to protect the neighborhood,” he says. I asked if he was prepared to use it. “Yes. And I wouldn’t have aimed for the legs,” he chuckles. Kritsada maintained a running list of who was in the community at all times and relayed the information about what he saw to the sub-district office. During this period, he and the five other volunteers were the sole authority governing this area of Sai Noi.

By the end of December, the floodwaters had receded from area. Residents returned and turned their attention to recovery. Cleanup crews made up of five households each collected debris from public areas and worked to put their homes back together. Then, through a system of barter and labor exchange — money was scarce due to the disruption of business caused by the flood — community members tackled larger jobs like repairing their houses. The villages were back up and running in less than a week. In the three months since the water had appeared, not a single member of the community had died or was seriously hurt. Against all odds, law and order had prevailed, and life returned, more or less, to the way it was before. With minimal help from the government, the neighborhood had survived the worst disaster ever to hit Thailand.

Near the end of a long conversation with Vichain and Kritsada, the dark stains of the high-water mark still clearly visible above us on a nearby wall, the discussion shifts to other cities that have been struck by natural disasters in recent years. I bring up Hurricanes Sandy and Katrina, and the hostility that residents of New Orleans and New York felt toward their own governments in the aftermath of those events. I ask them if they felt something similar. “No,” Vichain says without hesitation. “The government already had their hands full managing the water as it moved down from the north. They can’t take care of everyone.”

Cooperation came naturally to the residents of Sai Noi, in this case partly because of another shared identity: Their background as migrants from rural northern Thailand. In these regions, in particular the hardscrabble Isan area in the northeast, flooding is common and the people know how to deal with it. The residents of Sai Noi brought that knowledge with them to Bangkok. “I experienced my first flood when I was four years old,” Vichain says. “People in the countryside are better prepared. We had boats and built our houses on stilts.”

But there was more to it than that. Although they hadn’t come from the same province and didn’t know each other when they arrived, the residents shared a cultural sensibility that, when they found themselves in unfamiliar urban surroundings, brought them together as a community. “It’s very normal for us to cooperate like this. It’s instinct,” says Kritsada, echoing a sentiment I heard from a range of Thais involved in relief networks, including those who’ve spent their entire lives in cities. Sai Noi’s flood network now lies dormant. But when the next disaster comes, the community will re-establish it quickly. “Next time,” Vichain says, “we will be ready.”

Next time may come sooner than the last time. Researchers at MIT and Princeton University have found that the types of superstorms that used to make landfall once a century could now arrive every three to 20 years, and that so-called “500-year floods” might arrive as often as every 25 years, according to findings published in Nature Climate Change. “The volatility of large events of recent years has really grabbed hold of people, whether it’s Bangkok or Japan or Hurricane Sandy,” says Robert J. Sampson, a professor of social sciences at Harvard. “These things have made it clear that we have to think anew about how to prepare for disaster.” Sampson’s work, for instance, involves a method of disaster planning called ecometrics: “Taking the temperature of communities so you know which ones are vulnerable. It allows one to identify breaches of social defenses, not just seawalls,” he says. Like much of the thinking around social infrastructure and disaster preparedness, this is relatively new territory. But Sampson sees it catching on quickly. “There’s been a sea change,” he says. “It’s now on the radar.”

The Power of Low Expectations

Part of the reason cities like Bangkok and Wellington seem to be catching on to the role of informal social networks more quickly is simply because they have to. “New Zealanders are a scrappier people,” says Dan Neely from the Wellington Emergency Management Office. “We don’t have the level of resources that the U.S. has, so we’re forced to rely on our communities to a degree.”

Vichain echoes this sentiment. “If you expect the government to help you all of the time, you have to pay more in taxes, and Thais aren’t willing to do that,” he said. (This is a city where 150 formal ambulances attempt to serve 12 million residents, after all). Low expectations about government involvement meant that the people of Sai Noi were under no illusions about the level of assistance they would receive. And even if more outside help were available, they told me, it would have been no substitute for the on-the-ground expertise that residents were able to provide as events unfolded. “Based on our experience with the flood, it would work better for us to propose something to the government rather than waiting for them to help us,” says Vichain. “If we want something, we need to stick together and figure it out ourselves.” In turn, the government recognized its limitations and was prepared to cede authority to local networks.

A villager tending a field in Sai Noi.

This last point is salient for discussions about how to empower such informal networks in Western cities, where governments may be less accustomed to letting local actors take the reins. But maybe Western cities are more willing to cede control than one might expect — especially when overwhelmed by crisis. After Hurricane Sandy, when New York was consumed with major tasks like restoring power and subway service, one of the hardest hit neighborhoods, the Red Hook section of Brooklyn, also benefited from one of the most impressive informal responses. A relatively unknown community nonprofit called the Red Hook Initiative instantly transformed, in the words of its executive director, “from a small youth development center into a major hub for the disaster relief effort here.”

With an operation that was thoroughly informal yet, by all accounts, highly efficient and essential, the initiative turned its tiny headquarters into a makeshift storm-recovery center. It provided hot food, cell phone charging (it was one of very few local buildings to keep its power) and perhaps most important, a central command for much of the neighborhood’s flood-relief efforts. In the weeks that followed, the media marveled at the idea that such a rag-tag group could respond so effectively without being led by the government’s hand.

But they needn’t have been so surprised. Even when the sun shines, Red Hook is an unusually isolated neighborhood. It sits on a peninsula, untouched by the subway, and its denizens proudly consider themselves a city apart. Its remoteness seems to foster a shared identity, which felt palpable when residents later talked about organizing their own response in the wake of the storm. “I think many in the Red Hook community feel geographically and psychologically disconnected from the city,” an aide to New York City Speaker Christine Quinn told Capital New York, adding that confronting Hurricane Sandy’s wrath themselves, without top-down intervention, “may have been more empowering for the people of Red Hook than being rescued by a federal agency.”

A Thousand Little Sensors

In Bangkok, how to respond to the next flood is a question that has consumed Visit Hirankitti for the past year and a half. Visit is a professor of engineering at King Mongkut’s Institute of Technology in Ladkrabang, a district in eastern Bangkok that is home to high-tech manufacturing and the crown jewel of the city’s economic ascendance, glittering Suvarnabhumi International Airport. Until recently, though, Ladkrabang served as a catchment for flood waters, a mostly empty plain for the authorities to divert water into during heavy rains.

Visit was in the midst of exams when the flood arrived. Given the area’s history as a catchment, he expected things to get bad quickly. “But the water stopped rising at just above my ankles. This surprised me. I thought it would be much worse,” he says. As it turned out, with Ladkrabang’s recent development as a key economic zone — Japanese heavyweights Honda and Isuzu have factories here, and the airport is the hub of the country’s $30 billion tourism industry — the authorities were desperate to keep the area dry and functioning.

Throughout final exams, Visit was able to come to his office every day. Some of his students, though, were commuting in from harder-hit areas and decided to temporarily relocate their living quarters to the engineering lab, where they had a dry place to sleep and access to food and clean drinking water. Visit and his students watched with alarm as events unfolded across the city. “I became very frustrated. As an engineer, I wanted to do something and not just sit there and watch it happen on TV. I kept thinking, ‘What can I do for the country?’” When he finished grading exams, he recruited several students to stay on through winter break and assist him in developing a system that he hoped would help Thailand cope with future floods.

Engineering professor Visit Hirankitti has been developing a system through which citizens armed with iPhone apps would collect data during floods.

As far as Visit could tell, the key problem had been a lack of information. The authorities never really had a handle on where the water was and, as a result, couldn’t make effective decisions on how to manage it. In addition, Thai citizens, left in the dark, were caught scrambling when the flood arrived. “What I realized was that, as an engineer, I could provide data,” he says. Visit specializes in developing systems that synthesize complex information. His past projects include the country’s first electronic taxi dispatch system and a detailed GIS map of Thailand’s electricity grid. Visit realized that the country’s water management authorities, who were relying on antiquated sensors installed on a few dozen flood gates scattered around the country, needed something similar to respond effectively.

Perhaps counterintuitively, his first decision was to work outside the government, which he believes suffers from a toxic blend of incompetence and corruption. “I didn’t believe in going that route,” he says. Instead, he would rely on the strength of citizen involvement, which had proven to be so decisive in responding to the flood. Visit and his students set out to create a nationwide flood-monitoring system that would rely on thousands of volunteers, creating a vast, cheap, technologically advanced network that could provide up-to-date information to anyone who wanted it, including the authorities. After producing a prototype, he eventually decided to apply for government grants to fund further development.

On a recent afternoon in his lab, which was strewn with computers, tangles of cable and the fast-food-wrapper detritus indicative of late-night research, Visit showed me the version that he believed would be ready next year. The technology was simple: a PVC pipe housing a piece of twine and a small float, a circuit board to collect measurements and a Bluetooth device to transmit data.

Once he’s secured patents for the system, Visit hopes to set up over 1,000 of these sensors around the country. He estimates that they will cost about $30 USD apiece to produce, and he’s currently assessing various funding options, including donations and corporate sponsorship. The sensors will send data to thousands of volunteers who have downloaded a free iPhone app developed by one of Visit’s students. A central server will then collect the data from the phones and generate a three-dimensional map of water levels throughout the country, to be displayed on a public website. When operational, the system will be the largest flood-related network in Thailand. “With the increase in global warming and natural disasters, I have no doubt that another big flood is coming. The question is, what can we do about it? We want to see if people can help people to sort out the problem.”

Since the advent of the smartphone, developers around the world have launched apps designed to help people in crises. Organizations such as theAmerican Red Cross and the U.S. Federal Emergency Management Agency have created apps designed for emergencies, while privately developed software like BuddyGuard allows users to send out GPS-enabled distress signals. Meanwhile, city governments in urban areas such as Jacksonville, Florida, and Auckland, New Zealand, have created apps that provide real-time emergency information to residents. But Visit’s system is different in that it harnesses the power of users to generate information.

Given the strength of informal networks in Thailand, there is every reason for Visit to feel confident his system will work. Compared to the monumental tasks undertaken by volunteers to save their communities, installing an iPhone app and traveling to within range of a Bluetooth sensor would seem almost trivial. Yet relying entirely on unofficial networks is no solution to the problem, either. Volunteers working together are capable of powerful things, but there are limits to what they can achieve, especially when the authorities and official services underperform.

The view from the Klong Phraya Suren water gate.

I was reminded of this during a morning spent touring the Klong Samwa area with Samai Charoenchang, a former government official. Like Sai Noi in the northwest, Klong Samwa, located on the city’s northeast side, had been submerged in up to two meters of water. Samai drove me around the area in his minivan, introducing me to dozens of people who had joined relief networks. I met a woman who put her lucrative home-based TV production studio on hold for two months to set up a temporary kitchen in her front yard. When running at full capacity with 30 volunteer cooks, she churned out 3,000 free meals per day. I met a man in his seventies who helped deliver that food with members of his local Buddhist meditation center, which had transformed itself into an emergency distribution network. There were many others, and all said that while their networks were currently dormant — there was no flood to respond to — they could be brought back to life within hours.

But there was another, more sinister side to the networks. We stopped at a floodgate that regulates water on Klong Phraya Suren, a canal that runs north to south through Klong Samwa. In early November, at the height of the flood, the gate divided the area into two vastly different worlds. The area on the north side of the gate was completely flooded, while the southern side was dry. The city government, which controlled the gate, had decided to stop the water from flowing south toward central Bangkok, thus flooding the north. Enraged, residents on the northern side organized themselves into a small fighting force and attempted to seize the gate. The southern side responded in kind, and the two met in violent, pitched battles that lasted for two weeks. Armed men on both sides fired shots and fought hand-to-hand with one another before the police arrived and restored order (no one died, though there were plenty of injuries). “By the end, both sides wanted the other to suffer,” says Samai.

Suporn Rujapan in her living room next to a portrait of King Rama V on which the high water mark from the flood is clearly visible.

Regardless of these conflicts, Thais retain faith in their ability to respond to crises informally. Suporn Rujapan, a mother of grown children living on the city’s north side, stayed in her home for the entire duration of the flood. After initially finding herself a victim of the disaster, she quickly grew into a role as front-line leader of her community’s relief efforts, directing government and volunteer resources and becoming a minor media celebrity in the process. During a conversation in the kitchen of her modest concrete shop house, she echoes the thoughts of many Thais I had spoken with. “During the flood, we found that it was better to help ourselves than to rely on the government,” she says. Although she worries that her children’s generation has lost the sense of collective responsibility she feels so deeply, Suporn believes that the country will continue to rely on informal means to respond to future crises. “We’re Thais,” she says simply. “It’s in our nature to help each other.”

The Story of a Boat

“We have to go! We have to go!” Chetsarish Smithnukulkit says, his eyes wide under the silver bangs bouncing on his forehead. Chetsarish was standing in the offices of VS Service, a Thai production company that assists Hollywood film crews with local shoots, recounting the moment when he knew he would get involved in the flood. He didn’t have to take action; the worst of the water was dozens of kilometers away to the north. But Chetsarish’s calculus was simple: “We have the boat. We have the people. We have everything we need to help.”

The boat. Whereas what happened in Sai Noi was hyper-local, a small neighborhood helping itself when no one else could, a story repeated thousands of times across Bangkok, Chetsarish’s experience was different. His is a story of one man’s initiative, and how he marshaled not just his own resources, but also those of large volunteer networks and the government, to help an estimated 2,500 people. But first and foremost, this is the story of a boat.

Chetsarish Smithnukulkit and his crew with the boat that allowed them to aid people in a province north of Bangkok.

“I bought it five or six years ago from a film crew we worked with. They used it to shoot scenes in Rambo 4,” says Chetsarish. “I thought I could use it for another shoot. It didn’t have a motor, so we had to push it around with a bamboo pole.” Essentially a massive floating platform, the barge could hold nearly 50 people and hundreds of pounds of cargo. As the floodwater bore down on Bangkok, he got a call one day from the governor of Ayutthaya, a province north of the city. “He asked us to help. He said they had no food, no water, and that the people were in danger. He told me where to go,” Chetsarish says.

Chetsarish rounded up a crew of young production specialists from his company and student volunteers from a nearby university. But the journey would take hours, even days, if the crew were to push their way, gondola-style, all the way up to Ayutthaya. Chetsarish got on the phone again, this time reaching his friend Major General Adis Ngamchitsuksri, a high-ranking police official. “He said he needed a motor for his boat. I flew one in by seaplane the next day,” Adis says.

For the next two months, working 14-hour days, Chetsarish and his crew traversed the flood-ravaged city in their barge, which played many roles: Floating hospital, search-and-rescue-ship, mobile power station and aid-delivery platform. In coordination with local sources — government, volunteer networks and trapped citizens — they went to places the authorities simply couldn’t reach. They carried a generator that allowed those left behind to charge their cell phones and reestablish contact with the outside world. They transported doctors who provided medical care to the injured. They became a floating morgue, removing several dead bodies.

A woman feeding catfish at the temple next to the Klong Phraya Suren water gate.

They also had some close calls. Ten crewmembers, including Chetsarish, nearly died when they were electrocuted by a submerged power cable. And then there was their fear — perhaps irrational, in retrospect — of crocodiles, hundreds of which had reportedly escaped from illegal farms. “We heard rumors. We though they might be true,” he says, laughing sheepishly now. But the danger mattered little in the face of the overwhelming gratitude they encountered from those they helped. “When we came into an area, everyone stood and applauded,” he says, rubbing his forearms, remembering the goose bumps.

I ask Chetsarish what lessons he took from the flood. He leans in, his voice lowering to a near-whisper. “I have to say something bad about Thai politics.” The country’s two parties, in perpetual conflict, were not equipped to handle the crisis. “They look after themselves and not the people,” he says. “And besides, we’re ten times more efficient. The police had no way of helping people. That’s why they needed me.” On this last point, Major General Adis agrees. “We’re always ready to go to the public for help. We knew we couldn’t do this alone.” When the next flood comes, Adis will get on the phone and call his friend Chetsarish, the man with the boat. “The engine is working. I just checked it a couple of days ago,” Chetsarish says. “We’re ready to go.”

Dustin Roasa is a journalist based in Cambodia. His writing has appeared in the Los Angeles Times, the Guardian, Foreign Policy and Dissent, among others.

Flood Mapping and Flood Dynamics of the Mekong Delta


ISSN 2072-4292

Flood Mapping and Flood Dynamics of the Mekong Delta:

ENVISAT-ASAR-WSM Based Time Series Analyses

Claudia Kuenzer 1,*, Huadong Guo 2, Juliane Huth 1, Patrick Leinenkugel 1, Xinwu Li 2

and Stefan Dech 1

1 German Remote Sensing Data Center, DFD, German Earth Observation Center (EOC), German

Aerospace Center (DLR), Oberpfaffenhofen, D-82234 Wessling, Germany;

E-Mails: (J.H.); (P.L.); (S.D.)

2 Center for Earth Observation & Digital Earth (CEODE), Chinese Academy of Science,

Beijing 100094, China; E-Mails: (H.D.G.); (X.W.L.)

* Author to whom correspondence should be addressed; E-Mail:;

Tel.: +49-8153-28-3280; Fax: +49-8153-28-1458.

Received: 20 November 2012; in revised form: 1 February 2013 / Accepted: 1 February 2013 /

Published: 5 February 2013

Abstract: Satellite remote sensing is a valuable tool for monitoring flooding. Microwave

sensors are especially appropriate instruments, as they allow the differentiation of

inundated from non-inundated areas, regardless of levels of solar illumination or frequency

of cloud cover in regions experiencing substantial rainy seasons. In the current study we

present the longest synthetic aperture radar-based time series of flood and inundation

information derived for the Mekong Delta that has been analyzed for this region so far. We

employed overall 60 Envisat ASAR Wide Swath Mode data sets at a spatial resolution of

150 meters acquired during the years 2007–2011 to facilitate a thorough understanding of

the flood regime in the Mekong Delta. The Mekong Delta in southern Vietnam comprises

13 provinces and is home to 18 million inhabitants. Extreme dry seasons from late

December to May and wet seasons from June to December characterize people’s rural life.

In this study, we show which areas of the delta are frequently affected by floods and which

regions remain dry all year round. Furthermore, we present which areas are flooded at

which frequency and elucidate the patterns of flood progression over the course of the rainy

season. In this context, we also examine the impact of dykes on floodwater emergence and

assess the relationship between retrieved flood occurrence patterns and land use. In addition,

the advantages and shortcomings of ENVISAT ASAR-WSM based flood mapping are

discussed. The results contribute to a comprehensive understanding of Mekong Delta flood

dynamics in an environment where the flow regime is influenced by the Mekong River,

overland water-flow, anthropogenic floodwater control, as well as the tides.

Keywords: flood; flood dynamics; flood progression; water detection; inundation; radar;

Envisat; ASAR; WSM; feature extraction; time series; Mekong Delta; Vietnam