Intense Flooding Making Life More Than Miserable for 10+ Million in Rapidly Sinking Jakarta; “Bathtub Effect” Threatens Future of City

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Imagine the infrastructure of Port au Prince, a population density about a third greater than New York City*, the subsidence problems of New Orleans and a landscape like the Netherlands. What have you got? Jakarta. I mean, you know it’s bad when the Jakarta authorities are consulting with the Dutch for assistance in developing a plan to deal with the annual flooding.

Daily rainfall amounts could be as high as 1-2 inches across widespread areas. Locally however, isolated thunderstorms that are unusually vigorous or slow moving can produce 4-8 inches in a short period of time. This amount of rain will lead to street flooding, especially in northern Jakarta, where much of the city is below sea level. Poor drainage systems, in addition to other local factors in Jakarta, are likely to exacerbate any flooding that occurs.  Any additional rainfall over the next few days could cause additional flooding as many streams, rivers, and sewers are at capacity. Image: ImpactWeather

I don’t get it. No offense to the people of Port au Prince, but Jakarta is a modern country with impressive skylines and modern amenities. Something’s not right and it’s evident as the city slowly (actually, not so slowly) sinks and its population drowns. As an added slap in the face, it’s the rainy season presently and one thunderstorm has the potential to drop seven inches or more of rain in a very short period of time. Already some areas are under as much as six feet of water and more rain, some of it very heavy, is expected. This WSJ video was posted yesterday.

It’s not just Jakarta experiencing the heavy rainfall. The wet season is underway with the monsoon trough in place near the island of Java. Image: ImpactWeather.

In many areas subsidence is the curse of a growing and thriving society as more people consume more water from below the ground. The space previously occupied by water then compresses (or collapses) causing the ground (aka: the street, the foundation, the parking lot, the soccer field, the airport) to sink. Jakarta, the capital and largest city of Indonesia, is a subsidence nightmare. With more than 28 million people in the metro area (and we’ll assume most of them are using the recommended minimum of one gallon of water per day for drinking and even more for flushing and bathing, to say nothing of industrial uses), Jakarta’s water usage is contributing to 2-4 inches (5-10 centimeters) of subsidence per year. Some northern areas are sinking as much as 8 inches (almost 20 centimeters) per year. According to projections, 50% of Jakarta will lie below sea level in the next 10-20 years.

To combat this the Jakarta Coastal Defense Strategy has entered into an agreement with Dutch and Indonesian governments to create a feasibility study to build a dike on Jakarta Bay. The study is due in September and construction of the dike is expected to be complete by 2025. Similar discussions are underway in New York where, following Hurricanes Irene and Sandy, committees and panels have been formed regarding the feasibility of a dike (and other options) to protect low-lying New York City. A similar project to protect Galveston and the Houston Ship Channel, the so-called Ike Dike (after the devastating 2008 hurricane), has been all but abandoned because of the monumental cost.

The City of Jakarta is sinking. Can it be saved? Photo: Wikipedia

Let’s hope the Jakarta Bay dike is completed by 2025 (here in the U.S., that type of project might not get started until 2025). At the rate of 4-8 inches per year for 12 years, that’s an additional 48-96 inches (4-8 feet) of subsidence. Jakarta’s official elevation is 23 feet above sea level, but many areas are already below sea level.

Jakarta’s not alone. Bandung and Samarang join Jakarta as two other Indonesian cities that have been declared subsidence red zones by Indonesia’s Energy and Mineral Resources Ministry.

* Population density of New York City: 27,012 per square mile; of Jakarta: 39,740 per square mile. (Data: Wikipedia)

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