Water Resources Engineering (WRE) connects to economic, environmental, and societal issues. Our student, Maureen McCarthy, makes this connection in Bangkok, Thailand. This current event was reported on VOAnews, on January 12th, 2019, under the title, “Bangkok fights floods with thirsty landscaping,” by Thomson Reuters Foundation, Rina Chandran. This news article describes how flooding is very common in the city of Bangkok, especially during monsoon season. Every monsoon season, a large portion of the city is infiltrated with excessive amounts of water, and parts of the city are entirely submerged every year. The city was once composed of so many canals that the name “Venice of the East” was coined to describe its nature. Since then, so many of the city’s canals and waterways have been filled during construction, and the city has also experienced an exponential increases in urban sprawl. Because of this, climate experts conclude that the city is sinking by over 1 centimeter each year. So many canals are being filled up and there is such a low ratio of green space within the city that there is no place for all the water to go. This results in the increased runoff rates and flooding that the city has been experiencing.

The recent increase in flooding in Thailand is quantified in the case study titled “Hydrologic Sensitivity of Flood Runoff and Inundation: 2011 Thailand Floods in the Chao Phraya River Basin” by T. Sayama, Y. Tatebe, Y. Iwami, and S. Tanaka. This case study talks about the flooding that occurred in Thailand during the 2011 monsoon season which is considered the worst flooding in decades, putting over one fifth of the city underwater. The goal of the study was to quantify hydrologic sensitivity in Thailand, and it simulated inundation for the entire Chao Phraya River Basin. This study has shown that the flooding inundation volume in 2011 was 1.6 times greater than past flooding events. The news article talks about how Bangkok is built on the floodplains of the Chao Phraya River, and is an urban area that is expected to be greatly influenced by warming temperatures. As simulated in the study Hydrologic Sensitivity study, more and more of Bangkok is expected to become inundated with water in the coming years. In fact, it is projected that by the year 2030, about 40% of the city could be inundated (Sayama etal, 2014).

Reducing runoff is starting to become more and more of a concern in Bangkok, and initiative is being taken to reduce disaster effects. A “metro forest” is being built in the city, which would convert two acres of abandoned land into forested land in order to reduce urban sprawl. One of the city’s existing parks is designed at a three degree angle, collecting excess runoff in a retention pond at the park’s center. While water is flowing through the park to the retention pond, native vegetation and porous pavement filter the water. At the highest end of this existing park, there is a museum covered with a green roof, used to filter rainwater which is then stored in underground tanks. This park can hold up about 1 million gallons of water for the use of the city during the dry season. Not only does this park serve the purpose of dissipating the dangerous effects of flooding during monsoon season, but it also serves a purpose to benefit the city during the dry season, no water is wasted in this park. Green infrastructure is an important aspect of water resources engineering, and the purpose of green parks like this is to soak up water during flooding events, helping the city to adapt the changing climate by minimizing storm water runoff. The University of Michigan has been conducting research on Green Roofs, confirming that their main benefit is to mitigate storm water runoff within urban areas (Getter, Rowe, 2006).  Even though the addition of green infrastructure is very beneficial, several other initiatives have been taken to reduce flooding wreckage within the city, but not all of them take on such a direct approach. Part of the process of fixing Bangkok’s problem is to educate its people. A societal shift is necessary if the city of Bangkok is going to continue to thrive within the changing environment. If people can learn to take initiative themselves to learn about the effects green roofs and permeable driveways and yards have on the urban landscape, the city of Bangkok will make great strides in mitigating the effects of climate change.

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Figure 1: Residents of Bangkok during the 2011 flood season, the worst flooding in Bangkok on record.

References:

K.L. Getter, D.B Rowe. Benefits of Green Roofs. Benefits of Green Roofs. http://www.greenroof.hrt.msu.edu/benefits/index.html. Published 2006. Accessed May 1, 2019.

Reuters, Reuters. Bangkok Fights Floods with Thirsty Landscaping. VOA. https://www.voanews.com/a/bangkok-fights-floods-with-thirsty-landscaping-/4736199.html. Published January 9, 2019. Accessed May 1, 2019.

Sinking Bangkok fights to stay afloat with a new anti-flood park. South China Morning Post. https://www.scmp.com/magazines/post-magazine/long-reads/article/2166925/park-provides-anti-flooding-antidote-bangkoks. Published October 5, 2018. Accessed May 1, 2019.

Tanaka. Hydrologic sensitivity of flood runoff and inundation: 2011 Thailand floods in the Chao Phraya River basin. Natural Hazards and Earth System Sciences. https://www.nat-hazards-earth-syst-sci.net/15/1617/2015/. Published July 24, 2015. Accessed May 1, 2019.