Braving the Rain: Managing Development and Flooding in Ho Chi Minh City
Questions
- How do new urban developments in Ho Chi Minh City affect surface water management?
- How is surface water managed in Vietnam?
Background
Like many other developing countries, Vietnam faces environmental degradation due to its rapid urbanization and lax environmental regulations. One major problem is surface water management and chronic flooding. New urban centers that appeal to the upper-class and foreigners are being built all over Ho Chi Minh City.There are many problems with these new developments, such as unjust gentrification and poor surface water management. The land often has existing low-income housing and the residents are kicked out and relocated without compensation. There are also major hydrological ramifications to rapid development. The land surrounding Ho Chi Minh City is mostly low-lying wetland, which is not only more expensive and complicated to build on, but creates major hydrological problems as more impermeable surfaces are created (Eckert 2009). From 1990 to 2010, impervious surface have expanded by 4.4 times and the population increase approximately 2.2 times (Nguyen 2013). Even though these new urban centers are built with modern construction materials, the very wealthy who live in them face major flooding because of an already stressed drainage system. I would like to explore how this pattern of development affects the urban water management system and also how water resources are managed.
First, it is important to understand the common hydrological effects of urban development in the context of Vietnam. In Vietnam, strong monsoon seasons contrast with relatively dry seasons. This means that heavy rains periodically fall over the city where impermeable surfaces such as concrete allow the rain to drain into the stormwater/wastewater drainage system and then into the extensive system of canals. That is, of course, if the drainage system is clear and not over capacity like the one in Ho Chi Minh City (Long 2008). While it is clear that building more impermeable surfaces will cause flashiness (a sudden increase in the flow from stormwater runoff), it is not apparent that these new urban developments cause canals to be more flashy. Many of the new developments are catered to expatriate employees and upper class citizens and are built with more open green spaces and so may have less impermeable surfaces.
Methods
To answer this question I will primarily use streamflow data collected from gauges on canals in Ho Chi Minh City. I will collect average streamflows on many different canals in the city and also peak streamflow in each of the canals after storm events. For each of the canals I am studying, I will calculate the percent of impermeable surfaces in the surrounding neighborhoods. I will also look at when neighborhoods were built to see if canals with newer developments exhibit more signs of flashiness. I will look for patterns within the data and compare each to find any correlations.
I also aspire to understand how surface water is managed in Vietnam. Diving into the reading below by Gabi Waibel has greatly expanded my knowledge of policy and management in Vietnam, but also highlighted the complications and inefficiencies. I will create a social network analysis of the actors involved in surface water management. This will entail searching through governmental websites and scholarly articles to find collaborations between agencies, sub-agencies, and higher agency management. Assigning line weights depending on how often connections are mentioned will help to evaluate how strong different relationships are between surface water management agencies.
Resources
Eckert, Ronald, Michael Waibel. 2009. “Climate Change and Challenges for the Urban Development of Ho Chi Minh City / Vietnam.” No. 31. Pacific News.
Long, Ho Phi. 2008. “Impacts of Climate Changes and Urbanisation on Urban Inundation in Ho Chi Minh City.” 11th International Conference on Urban Drainage, Edinburgh, Scotland, UK. Ho Chi Minh City University of Technology.
Nguyen Dzung Do. 2013. “Urban form evolution in Saigon River Basin & impacts on hydrologic performance.” CPG COnsultants. 49th ISOCARP Congress 2013.
Waibel, Gabi. 2010. State Management in Transition: Understanding Water Resources Management in Vietnam. 55. ZEF Working Paper Series. http://www.econstor.eu/handle/10419/88390/.