Rising sea levels threaten Bangkok

The biggest looming threat to Bangkok today are rising sea levels. Climate change is causing global warming. There have been numerous studies that have been conducted about rising sea levels caused by human induced climate change. It was concluded sea level rise is due to manmade climate change. There is no question there is extensive literature about climate change, sea level rise, sustainability and planning for the expected catastrophe.

However, there are only a few options written options to counteract sea level rise and no concrete planning for the inevitable catastrophe. Most studies approach this topic from an engineering standpoint, including proposals for sea walls, dikes, groins or jetties, earth berms (or tall mounds of dirt), physical barriers, construction of barrier islands, sand replenishment of affected beaches and other technical options. However, nothing can be found to date that addresses the human side of the equation, the looming problem of moving people or populations away from affected coastal areas.

There is no question that the sea level is slowly rising. It will soon pose a grave hazard to the world’s population, commerce and livelihood. It will have a direct impact on earth’s sustainability. Even now there has been serious incidents of flooding, stronger storm surges from large cyclones, hurricanes or typhoons, shoreline and land erosion and other physical problems like seawater encroachment into land based fresh water sources. There is a general scientific consensus that sea levels have been rising at approximately two millimetres per year since 1850 according to scientific measurement and record keeping.

During the Pleistocene Epoch some 18,000 years ago, or during the last Ice Age, it is estimated that the sea level was 100 metres lower than in the present time. The sea level has already risen 10-12.5 centimetres in the last 50 years. Recent scientific studies of sea level change have shown that the average increase or rate of rise has been between one – three millimetres/year. It is now estimated that by the year 2070 that sea levels may be 20 – 70 centimetres higher than at present. Some scientific studies have stated that if all the ice melted in Antarctica and Greenland, then sea level would rise by some 75 metres.

This side effect is melting glaciers, snowfields and sea ice, so the world’s oceans have been seeing an incremental rise in sea level for hundreds of years. Manmade global warming is a phenomenon that is fueling ocean levels to rise. Due to more heat in the air and the oceans, heated water will expand thus making the problem much worse. In one scientific analysis, it was found that all coastal areas will be heavily impacted by rising sea levels. As the world’s population increases in most non Western countries, urban coastal and adjacent areas will be the centre of those population increases and flows into centres for higher income earning opportunities. This means urban areas are growing as rural areas lose population. Global warming poses further serious risks, and a study by the OECD has estimated that 5.138 million people in Bangkok may be exposed to coastal flooding by 2070, the seventh highest figure among the world’s port cities.

Some of the world’s largest or most important low lying seaport cities at great risk will include New York City; Kolkata, India; New Orleans, Louisiana; Miami and Tampa Bay, Florida; Hong Kong and Shanghai, China. Also some low elevation parts of the U.S. like the much of the states of Louisiana and Florida are also at grave risk of being permanently submerged.

It is estimated one third of the world’s population lives within 56 kilometres of a coastline. More than one third of the world’s economic infrastructure are concentrated in coastal regions with elevations below 1.5 metres. Scientists have stated that a 0.3 metre sea level rise will push shorelines back about 30 metres. A 1.5 metre sea level rise is estimated to push shorelines back 136 metres. It has also been estimated that in the year 2020 that 65% of the world’s population will live along the coastal margins.  Another report states that 20% of the world’s population already lives on coastal areas that might be inundated or changed dramatically if sea levels rise even one metre. Low lying river delta areas with densely packed populations in Bangladesh, Nigeria, China, Malaysia, India, Egypt and Thailand will be at the great risk. The populations of island states are at most immediate risk because of rising sea include the Kiribati, Seychelles, Nauru, the Maldives, Palau, the Marshall Islands, Tuvalu, and Vanuatu.

The city of Bangkok is at additional risk because of decades of unrestrained pumping of groundwater. This is causing saltwater intrusion especially when the Chao Phaya River has a low flow. It allows saltwater to push into the fresh water aquifers in coastal areas where fresh water is being withdrawn faster than it can be replaced. This is also causing the southern part of the Chao Playa River valley, where Bangkok is situated, to subside. Coupled with the rise in the Gulf of Thailand it is estimated that by the year 2030 major parts of Bangkok will be submerged.

Many millenniums ago, what is now Bangkok, was at the bottom of the Gulf of Thailand. The mouth of the Chao Phaya River was at Lopburi, now 150 kilometres Northeast of Bangkok. However, many scientists have stated that Bangkok will once again, if not soon, be at the bottom of the Gulf of Thailand due to rising sea levels. The gravest threat to Bangkok and the surrounding area is being eventually submerged.  The city is especially vulnerable to sea level rise over many other major cities in the world.

Bangkok suffers from two grave handicaps. First the city has an average elevation of only 1.5 metres above sea level. Second is due to extensive ground water pumping over the decades, this action has lowered the city’s land elevation. Although ground water pumping has been somewhat mitigated over the years, there are some parts of the city that are now 1 metre below sea level. Some scientists fear that Bangkok and its 12 million inhabitants will be submerged at the start of the next decade. Compounding the problem are several other factors. The land’s subsidence in the whole area has increased the risk of increased flooding. Bangkok was already prone to periodic flooding due to it low elevation and an inadequate drainage system. Additionally, the city’s drains are frequently blocked by trash and rubbish, especially plastic waste.

  The city now relies on flood barriers and augmenting drainage from canals by pumping and building drain tunnels. Even so, parts of Bangkok and its suburbs are still regularly inundated. Heavy downpours resulting in urban runoff overwhelming drainage systems. Runoff discharge from upstream areas are major triggering factors. Severe flooding affecting much of the city occurred in 1995 and 2011. In that later year, most of Bangkok’s Northern, Eastern and Western districts were flooded, in some places for over two months. Coastal erosion is also an issue in the Gulf coastal area, a small length of which lies within Bangkok’s Bang Khun Thian District.

There are some individuals who cannot wait for official help to relocate elsewhere or defend themselves where they live from rising sea levels. The local people there are not waiting for the Thailand government to intervene to protect them from rising sea levels, preferring to take matters into their own hands. There are several examples of individuals conducting self-financed self-help projects to prevent the encroachment of seawater into their inhabitations and to protect their homes and farms or land based fisheries. Some Thai farmers and fishermen at the mouth of the Chao Phraya River have already erected earth berms by themselves to prevent the Gulf of Thailand’s waters from encroachment onto their lands and homes. The rising sea waters have been affecting, or ruining, their livelihoods. 

This is also being done in other places around the world. In Thailand, traditional teak wood houses have been long placed on stilts in low lying river areas for well over a millennium. This was to avoid both seasonal monsoonal and typhoon flooding plus avoid wild animals, insects, thieves and snakes. Residents in the Amazon River valley in Brazil have long built their houses on stilts to avoid the annual Amazon River high flooding levels. During half the year portions of the Amazon forest are naturally flooded up to 20 kilometres from the river by several metres of water. Houses have also been built in stilts all through SE Asia due to the annual monsoonal flooding in Laos, Cambodia, Burma and Vietnam. In another example, dozens of large summer homes along the New Jersey beach are already being elevated and placed on large stilts.  

There are only two solutions to his looming problem. Either protect people in place by some means or move everyone to higher ground. It will be financially and physically impossible to do either or both, i.e., move everyone to higher ground or protect every coastline.