Where the big rivers are

The biggest river deltas are flat and that’s why the cities which occupy some of the have expanded so much, so quickly. The last 50 years has seen a big population expansion on deltas – cities like Dhaka in Bangladesh. Twelve megacities on deltas have expanded in terms of populations from 62 million in 1975 to 153 million in 2010, an expansion that is not slowing.

‘Global Change’, which is the magazine of the International Geosphere Biosphere Programme (IGBP), has brought out a special number of deltas and the risks borne by city administrations that occupy deltas. The IGBP, in its own words, “coordinates international research on global-scale and regional-scale interactions between the Earth’s biological, chemical and physical processes, and their interactions with human systems”.

Flooding both from rivers and the sea is increasing. There was a storm surge in the Irrawaddy in Myanmar in 2008 when 200,000 people were killed. But people are still living on the delta. However, the estimate is that two million people have left the Indus delta in Pakistan to move to higher ground as salt water has invaded the farming zone. [A larger version of the graphic above can be found here (1.4MB). The original IGBP infographic which I have modified can be found here – caution, big file (12.7MB)].

The Po delta (near Venice in Italy) subsided largely because methane was being pumped from underground. They stopped the pumping and the delta is sinking 10 times less fast than it was. But the land surface is not actually rising, and it’s still below sea level. The Chao Phraya River Delta (along which Bangkok is built) subsided because of groundwater being pumped out to supply Thailand’s thirsty capital. So they introduced a tax on water use, such as showers. In Shanghai, the local government slowed the rate of pumping water out of the ground.

However, when countries set up commissions to look at the natural environment, it’s often water/river courses they’re concerned about, like with the Rhine. There is not so much focus on the delta. Where countries have tried geo-engineering, they can scarcely bear the prohibitive costs. It is estimated that China in the 15th to 18th centuries used 12-15% of its historical GDP in attempts to control the Yellow River from spilling out into its floodplain, but these gigantic efforts were never really successful.

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Floodwaters surround Bangkok

Update 2011-10-26 – Bangkok is braced for its zero hour which will be 0730 local time on 27 October 2011. That is when a high tide will coincide with a new surge of water coming down the Chao Phraya from central Thailand.

People wade through a flooded street in Bangkok October 25, 2011. Photo: AlertNet / Reuters / Sukree Sukplang

Reuters Alertnet has reported that floods swamped a new area of Thailand’s capital on Wednesday as some shops rationed food and Bangkok’s governor warned of “massive water” on the way that could put many parts of the sprawling city in danger by the end of the week. Large-scale evacuation was underway in Bang Phlad, a riverside area some way from Bangkok’s inundated northern districts, as floods hit the capital on a second front, deepening anxiety in the city of 12 million people, many of whom were expected to flee before a special five-day holiday.

“Now we’re at a critical moment, we need to monitor the situation closely from 28-31 October, when many areas might be critical,” Bangkok Governor Sukhumbhand Paribatra told reporters on Wednesday. “Massive water is coming.” Sukhumbhand said 90 percent of the northern Don Muang district was under water and Bang Phlad was in a critical situation. Fourteen city districts were threatened by floods and two more could be hit on Thursday, he said.

Bangkok residents scrambled to stock up on food, but bottled water was nowhere to be seen and some shops restricted customers to small quantities of food to prevent hoarding. Bus stations were packed as thousands prepared to leave the city. With high tide approaching in the Gulf of Thailand, Seri Supharatid, director of Rangsit University’s Centre on Climate Change and Disaster, said the city’s fate rested with river dykes holding.

“In the worst-case scenario, if all the dykes break, all parts of Bangkok would be more or less flooded,” Seri said. Prime Minister Yingluck Shinawatra, who said two weeks ago that Bangkok was likely to escape the floodwaters, said on Wednesday that it could be flooded for as long as a month. “But we shouldn’t face water as high as two or three metres or staying for two or three months as we’ve seen in other provinces,” she told reporters.

Residents talk to a policeman as floods advance into central Bangkok, Thailand, October 26, 2011. Photo: Reuters

The rising tide could complicate efforts to drive water from the swelling Chao Phraya river out to the sea, putting more pressure on a city that accounts for 41 percent of Thailand’s gross domestic product. Three northern districts of Bangkok have been under water since Saturday, with army vehicles driving at a snail’s pace through 1.5 metres of water, ferrying evacuees away on roads shared by cars and boats.

Some people were being evacuated for a second time, with 4,000 sheltering in Don Muang moving to the province of Chon Buri. Evacuees at a university in Pathum Thani province also had to move on as floodwater engulfed the campus. To tackle the flooding, the authorities have pumped an estimated 8 billion cubic metres of water daily through canals and a river around Bangkok’s east and west towards the sea. But the large volume of water flowing through the city remains a concern, with the vast Chao Phraya river at record levels and running past high-end hotels, embassies and the Sathorn and Silom areas of the city’s business district.

Water has engulfed two areas, with levels climbing higher than half a metre in the densely populated Bang Phlad district near to the Chao Phraya and closer to the commercial heart. Overloaded trucks shuttled out evacuees from Bang Phlad, gas stations were inundated and shop owners pulled down shutters and added sandbags to makeshift defence walls. “My shop is damaged. I’ve prepared for this, but it’s not enough — there’s too much water,” said grocery store owner Vichit Pookmaitree. As panic grew, shoppers at a central Bangkok hypermarket run by Big C Supercenter Pcl were being restricted to one packet of rice and one tray of eggs. Toilet paper was also being rationed. Bottled water had run out.

The Voice of America reported that authorities in Thailand are turning to desperate measures as they try to prevent the Chao Phraya River from overflowing its banks and inundating central Bangkok. The Thai navy has deployed a fleet of ships to the Chao Phraya and other rivers, where they are using their propellers to try to speed the flow of water through the city to the sea.

Prime Minister Yingluck Shinawatra said she is no more than 50 percent certain that the city will be spared, despite the navy efforts and constant reinforcement of the embankments. In an address to the nation Tuesday evening, she said that if the embankments fail, the city could be flooded to a depth of 1.5 meters in places. “The flood water levels in Bangkok, due to variation of the plains’ altitude, could range from 10 centimeters to 1.5 meters. We will control the runoff to allow only the least water to enter Bangkok, to flood for the least number of days, and will stop the flow of water in the quickest possible way, by using all the drainage means we have,” said Yingluck.

Update 2011-10-23 – The Chao Phraya River has burst its banks and water levels have risen in some of Bangkok’s northern suburbs.

Despite assurances by Flood Relief Operations Command that the river’s spillover could be drained off, reported by The Associated Press, Thai troops raced to fortify defense walls Sunday to protect two key industrial zones. Bangkok authorities said city residents should brace for more high tides in the coming week, which could cause rivers to back up.

Floodwaters had spilled onto highways north of the capital, including near Bangkok’s second airport in the Don Muang district, the AP reports, adding that the situation was “dire” away from the highways. Prime Minister Yingluck Shinawatra said: “Water is coming from different places and headed in the same direction. We’re trying to build walls but there will be some impact on Bangkok.” High tide in the Gulf of Thailand by the end of the week could complicate the situation.

Thailand’s worst flooding in half a century has affected a third of the country and has been bearing down on Bangkok since early last week. Twenty-eight of 77 provinces and 2.46 million people are affected, with water covering an area the size of Kuwait. Yingluck said on Saturday it could take as long as six weeks for the water to subside. Since late July, 356 people have been killed and at least 113,000 moved to more than 1,700 makeshift shelters.

The full force of the flooding has hit central provinces and those on the edge of Bangkok, where water levels have reached as high as three meters, with vehicles completely submerged and some residents believed to be stranded in their homes. The northern Bangkok districts of Don Muang and Lak Si were inundated on Sunday after floodwater spilled out of the Prapa canal. Boats and cars were seen side by side on a main road, with people seen wading through water or boarding trucks for evacuation as water levels were up to two meters in some parts. Thai television showed footage of a two-meter long crocodile caught by authorities in a residential area.

An aerial view of a flooded area in Nonthaburi province October 12, 2011. Photo: Reuters / Sukree Sukplang

Update 20111021 – Thailand battled to protect the capital Bangkok from being swamped by water on Friday, with canals full to the brim after devastating floods across the region that sources in neighboring Myanmar said had killed at least 100 people there. Reuters has reported that after trying to hold the line for a week, the Thai government opened some canals on Thursday to allow water to run through the inner city, carrying the risk of inundating some districts but relieving pressure on dikes.

At least 100 bodies had been found in the low-lying parts of central Myanmar along the Irrawaddy River, with at least 100 more missing after floods and torrential rains since Wednesday, according to a reliable source in Pakokku, about 450 km (280 miles) north of the biggest city, Yangon. The source requested anonymity and cited information provided by a local administration official. Residents contacted by Reuters in Monywa and Kyaukse towns said there was damage to property and crops, but could not confirm casualties.

Villagers built a wooden bridge in a flooded temple complex in Nonthaburi province, on the outskirts of Bangkok October 16, 2011. Photo: Reuters / Chaiwat Subprasom

Government officials in Thailand were not available for comment and state-controlled media made no mention of the rains and floods. The floods have also killed at least 247 in Cambodia and displaced tens of thousands of people. The floods are the worst in Thailand in five decades and have killed at least 342 people since July and devastated industrialized areas to the north of Bangkok.

The crisis is the first real test for politically inexperienced Prime Minister Yingluck Shinawatra, whose government has had to form uneasy alliances with the military and political rivals to coordinate the relief effort. Bangkok’s metropolitan authority is controlled by the opposition Democrat Party, while the military has a frosty relationship with the ruling Puea Thai Party because of its de facto leader and Yingluck’s brother, Thaksin Shinawatra, the self-exiled former premier overthrown by the army in 2006.

The flood problem was building even before she took office in early August and looks set to cost industry more than $3 billion, slashing economic growth this year. The 44-year-old former businesswoman is resisting calls to declare a state of emergency, saying authorities are able to manage.

A man carries his daughter through flooded streets in Pathum Thani province, on the outskirts of Bangkok Oct 18, 2011. Photo: China Daily/Agencies

20111020 – The floods across South-East Asia have hit Thailand particularly hard and floodwaters are now threatening Bangkok, home to more than 9 million people.

The region expects monsoon rains at this time of year, but not of the intensity of the past few weeks, as The Economist has pointed out. Over 270 people have been killed, about 700,000 homes destroyed or damaged and large areas of the central plains region have been inundated.

Prime minister Yingluck Shinawatra has been touring the flooded areas. But her government’s response has been criticised as tardy and ineffective. The longer-term economic consequences of the floods have been estimated by the University of the Thai Chamber of Commerce (UTCC) at as high as 150 billion baht ($4.8 billion), and that total will rise significantly if Bangkok is badly affected. The rice-growing areas of the rural north have been hardest hit; more than 3.4m acres (1.4m hectares) of farmland are already under water.

Residents walk through flooded streets in Pathum Thani province, on the outskirts of Bangkok Oct 18, 2011. Photo: China Daily/Agencies

Here is a set of reports by The Nation, Thailand’s leading English newspaper, which helps explain the calamity:

A close aide to former prime minister Thaksin Shinawatra yesterday suggested that the government immediately revise its flood-prevention plan to protect the inner city areas from severe flooding. Sudarat Keyuraphan, in her capacity as an adviser to the government’s Flood Relief Operation Centre (FROC), said her plan calls for releasing floodwater from upstream provinces into Nakhon Nayok and Chachoengsao to the east of Bangkok, and allowing some areas of the city to be flooded. “Bangkok has to accept part of the water in order to help reduce the burden,” Sudarat said. She added that FROC chief Pracha Promnok has agreed to her idea and that she would later raise the matter with Prime Minister Yingluck Shinawatra.

UN Office for the Coordination of Humanitarian Affairs (OCHA) situation map of Bangkok floods, 17 October 2011

She warned that the government’s current plan of blocking the floodwater in upstream provinces would only help increase the water pressure. Any leak in the temporary flood walls could lead to severe flooding in Bangkok’s central areas, including the Victory Monument. “We now need to brainstorm to release the 10,000-plus million cubic metres of water into the sea as soon as possible. We can’t allow the water to mass up and attack Bangkok,” the banned politician said.

A woman sells rubber boots in a flooded street in Rangsit near Bangkok Oct 18, 2011. Thailand's cabinet met on Tuesday to discuss the mounting economic cost of floods that have killed 315 people, and residents of Bangkok were told not to drop their guard even if the immediate danger to the capital had passed. Photo: China Daily/Agencies

Kohlak Charoenruk, deputy chairman of the National Disaster Warning Committee, yesterday called on the prime minister to decide whether to allow floodwaters from upstream provinces to naturally pass Bangkok’s Chao Phraya River and canals into the sea. He said that the government’s attempt to keep the massive floodwater in provinces north of Bangkok would only help increase the water pressure. “It’s the nature of water to flow downstream into the sea. When you block a lot of water, it will mass up to become a tsunami and could finally hit Bangkok,” he said. He added that Bangkok is on a natural channel for the water from upstream to flow into the sea.

About 1.2 billion cubic metres of water are expected to sweep around Rangsit Canal. A massive run-off from the North is bearing down on Bangkok faster than expected and should reach Rangsit Canal tonight, Governor Sukhumbhand Paribatra said yesterday.

Cartoon in The Nation expressing the frustration of flood-affected residents with their government. The woman in Burberry boots is prime minister Yingluck Shinawatra.

He said all the sluice gates of Canals 1-12 were opened. The water from submerged Nava Nakorn Industrial Estate would arrive first followed by the water from Rapeepat Canal. The flood is expected to surge into Canal 2 and Hok Wa Canal, the frontline defence of the capital, tomorrow.

Sukhumbhand earlier urged 200 households along Hok Wa Canal to seek shelter at Ritthiyawannalai 2 School, which could accommodate 1,000 people.  He also told residents in seven at-risk districts to move their belongings and electric sockets to higher elevations and prepare for evacuation. The seven districts are Sai Mai, Bang Khen, Khlong Sam Wa, Nong Chok, Min Buri, Lat Krabang and Khan Na Yao. He said 1.2 billion cubic metres of water were expected to sweep over areas around Rangsit Canal, which could handle only 400 million cubic metres. Prime Minister Yingluck Shinawatra said construction of flood barriers along Rangsit-Pathum Thani Road north of Bangkok has almost been completed.

The situation in Nonthaburi’s Bang Bua Thong and Pak Kret districts was critical yesterday, as a massive volume of water suddenly flowed into the municipality area and markets, inundating hundreds of vehicles and causing residents to flee their homes. Most of the six districts in the province were being hit by huge run-offs from provinces to the north such as Ayutthaya and Pathum Thani, said Nonthaburi Governor Wichian Phuttiwinyu.

Thai soldiers try to protect the highway as floods advance into Rangsit near Bangkok Oct 18, 2011. Photo: China Daily/Agencies

“The problem is that we cannot estimate how much water will enter our area. We are familiar with the levels of the Chao Phraya River, but this time it’s very abnormal, as we don’t know when and where it will arrive,” he said. The inundated area in Nonthaburi was expanding to Bang Yai and Bang Kruay districts yesterday.

Much of the province was turned from agricultural land into residential areas during the boom years of the real-estate business. Many areas, notably along the western bank of the Chao Phraya, have been connected by canals, resulting in a speedy flow of water. Bang Bua Thong was in fact first hit last week, but the authorities built barricades to keep water from flowing into municipality areas and markets.

However, the sandbag barrier failed to prevent water breaking through yesterday and a massive volume flowed into the inner part of the district, notably the area near Wat Lahan and Bang Bua Thong Hospital. As of yesterday, almost 100 per cent of Bang Bua Thong district was inundated, said Somchit Chandaen, former chief of the Tambon Bang Bua Thong Administration Organisation. The deepest water was as high as 2.5 metres above ground, he said.

The UN has a number of agencies coordinating flood relief efforts in Thailand. The UN Office for the Coordination of Humanitarian Affairs (OCHA) told reporters in Geneva that a UN Disaster Assessment and Coordination (UNDAC) team was on standby to deploy in the stricken countries if requested. The UN Development Programme (UNDP) offered support to the Thai Government to deal with the floods that have killed more than 280 people and affected more than two million since July. More than 80 per cent of the country’s 76 provinces have been affected, and in excess of 900 industrial plants and farmland inundated.

Residents and a dog make their way through floods as they leave Nava Nakorn industrial estate in Pathum Thani province, suburb of Bangkok Oct 18, 2011. Photo: China Daily/Agencies

The UN has been in regular contact with the authorities, including the Thai Department of Disaster Prevention and Mitigation, and has been monitoring the humanitarian and development impacts of the floods. According to the country’s irrigation authorities, 11 out of the 26 major dams in Thailand currently hold more water than their established capacity, while others are between 82 and 99 per cent full and the excess water needs to be released, which must in turn necessitate more evacuations of people downstream.

UNDP has boosted its capacity to assist the people of Thailand, setting aside both financial and technical emergency resources, and will continue to work with the Government to support the country’s longer-term recovery and rehabilitation. At the weekend, the Under-Secretary-General for Humanitarian Affairs, Valerie Amos, warned that the flood disaster in South-East Asia could worsen with river levels still rising and heavy rainfall forecast. Some 700 lives have been lost in Cambodia and Thailand, while in Laos, the Philippines and Viet Nam, homes, crops and vital infrastructure have been destroyed. Millions of people living in low-lying areas remain vulnerable to further destruction, a UNDP spokesperson said.