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December 09, 2019

Some cities around the world are sinking

By Khin Maung Myint

During our younger days, we knew of only one city that was inundated the whole year round. The thoroughfares are a network of canals instead of paved roads. At school, when we first came to learn about that city, we were astonished and wondered how people could live in such a place. That was what our not yet matured brains thought. However, those conditions made Venice, which is the name of that city, famous as a tourist attraction up to this day. Later, when Bangkok was built, it was dubbed the “Venice of the East” by the globe trotters of the old, due to numerous canals that provided transportations around the city in those days.
I haven’t been to Venice, but as a frequent visitor to Bangkok, I am familiar with the canals that can still be found in many places in that city, which provide small watercraft to ply on them. Those riverine ferries not only supplement the city transport system, but provide fast modes of travel for some commuters who are in a hurry, in a city notorious for traffic jams. The canals are also used to drain rain waters to prevent flooding.
Today Bangkok is sinking. During the monsoons the floods are becoming more severe and frequent, causing traffic jams more annoying and damages to properties more extensive. In 2011, the flooding in Bangkok caused severe damages to homes and factories. The hardest hit was the Ayutthiya area. As most manufacturers had their factories in that area, many had now shifted to higher grounds outside Bangkok; some even moved to other countries in the region. The Japanese Honda car manufacturer suffered great loses due to that flood. When the flooding happened they had over a thousand vehicles ready for shipment abroad. From the TV footages only the rooftops of rows upon rows of the new vehicles parked in the factory grounds were visible. The company crushed all the drowned cars without salvaging any parts for reuse – to maintain their quality control and safeguard their brand name.
According to experts, there are some major cities around the world that are being faced with the threats of sinking. Here, it would be necessary to know what causes such sinking. There are many factors that contribute to that phenomenon. However the immediate cause is the subsidences or caving ins of the ground, which are the results of excessive ground water, crude oil and gas extractions. These geological conditions coupled with the deteriorating climatic conditions that caused ocean levels to rise due to extensive melting of ice glaciers around the world are the main contributors to such disasters. Ten top cities from around the world are identified as the most endangered cities that could succumb to sinking.

The ten top sinking cities
The cities that are fast sinking are:-
1. Jakarta, Indonesia
2. Manila, Philippines
3. Ho Chi Minh City (Saigon), Viet Nam
4. New Orleans, Louisiana, USA
5. Bangkok, Thailand
6. Osaka, Japan
7. Dhaka, Bangladesh
8. Shanghai, China
9. Venice, Italy
10. Alexandria, Egypt
Besides these ten cities, London and New York, too, are facing the same fates. London is under threat of ‘sinking’ as global warming makes sea levels rise and so also is the city of New York.
Currently Jakarta is ranked as having the highest rate of sea level rise in the world, with a rise of ten feet (3 meters) in the last thirty years. This is primarily due to the fact that the city is sinking, adding to the quickening rate of the rising sea. The Indonesian authorities are urgently taking drastic actions similar to those taken by Netherlands, to save Jakarta. Some sources says they are also considering replacing Jakarta with a new capital city. It is said, if the sinking cannot be put under control the whole city would be under water by 2050.
Let us have a glimpse of what Netherlands did to counter the sea rises. Due to its low elevation, approximately two thirds of Netherlands is vulnerable to flooding and as the country is densely populated, flood control is an important issue for them. Natural sand dunes and constructed dykes, dams, and floodgates provide defense against storm surges from the sea. The dykes prevent flooding from water flowing into the country by the major rivers – Rhine and Meuse, while a complicated system of drainage ditches, canals, and pumping stations keep the low-lying parts dry for habitation and agriculture.

Climate change is a “threat multiplier”
Climate change could act as a “threat multiplier” to the existing problems such as sinking ground and subsidence due to ground water, oil and gas extractions and bad planning. The climate change is getting from bad to worse over the years due to the behaviours of the humankind. The human inflicted deforestations, use of fossilized fuels, over populations, over-breeding of animals for consumption are all contributing to the excessive carbon emissions, which in turn trigger the greenhouse warming.
Right at this very moment there are over a hundred wildfires raging on in the Artic region, which I had discussed in my previous article “The Arctic is burning: how will it affect us”, which was covered in the 5 August issue of The Global New Light of Myanmar. There I had mentioned of the unprecedented heat-wave causing the Arctic to burn and cause the polar ice to break up and melt at alarming rates. This plus the melting of the Antarctic and the mountain glaciers around the world that had been going on for quite sometimes now, would certainly raise the ocean levels significantly and in turn expedite the sinking of the low-lying places along the coastlines. Thus it is undeniable that the climate change is “the threat multiplier” to the existing problems.

Lessons to be learned from others’ experiences
It would be worth mentioning what our neighbour, Thailand had done and is doing to control the floods, which ravaged their country every year. There are numerous dams and diversion weirs, dykes and pumping stations built in places that are prone to flooding. These infrastructures proved to be very efficient and effective. They are building coastal dykes and retaining walls to deter erosions of the coastline caused by storm surges and also at the river mouths to prevent sea water surging inland during the storms that are frequent in the Gulf of Thailand.
One good example of such an undertaking is a 10 kilometer long coastal dyke at the mouth of the Chao Phraya River. The project started back in 1992, to prevent floods and defend against storm surges reaching Samut Prakan, where an industrial estate is located. The construction was done on a stretch of very soft mud flat, which usually is submerged at high tides. As the soil over which the dyke was built is too soft and such a project was the first of its kind, a German consultancy firm was hired to oversee the foundation treatment using a new technology not yet familiar in Thailand, then. Today, the said coastal dyke is still serving its purposes efficiently. I learned about that dyke from a Myanmar water resources engineer, who undertook the construction of that dyke as a project manager.

Conclusion
In anticipation of the looming ocean rises, our country too should take the example of Thailand and consider building coastal dykes at the major river mouths, namely the Ayeyarwady River delta entrances, the Yangon River, the Ngawun or Pathein River, the Salween River and the Kaladan River in Rakhine, for instance. Here to drive home my point, allow me to briefly mention the tidal conditions in the Yangon River. The tidal range, the difference between the heights of low and high tides, is about 20 feet average in normal circumstances, if I remember correctly. There could be a couple of feet more during the extra-ordinarly high tides, thus during such times the low lying places in Yangon were usually submerged, in the past, but in recent days those conditions seem to have improved.
However, we should not ignore the fact that sea levels are expected to rise rapidly unless global warming is maintained at 1.5°C or lower, above the pre-industrial levels, an ambitious target set by the Paris climate agreement (COP21). Thus, with the worsening climate change, the effect of the rising sea levels due to the melting of ice glaciers could exacerbate the floods in Yangon area in the near future. To my knowledge, our Irrigation Department at one time had planned to build such coastal dykes at the entrances to the Ayeyarwady delta. I knew this for a fact, because in 1984 I had helped someone to translate that plan written in English into Burmese. If it should have been implemented, the loss of lives and properties due to Cyclone Nargis would be far less.

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