Urban flooding response: Jakarta-Garuda expectations

Jakarta of Indonesia, located on the lowlands and sunk, 40% of the city’s area is currently lower than sea level. In addition, the drainage system has from colonial times was too old. This makes things very prone to floods in Jakarta. The Jakarta authorities are placing hope on project worth 40 billion dollars, “the great Garuda”.

The sinking city

Jakarta is located on the North coast of Java, at the mouth of Ciliwung River on Jakarta Bay. It is a region of the basin, the lower level from 2 m to 50 m higher than the sea level and an average elevation of 8 m above the sea. 40% of the city is below sea level, especially in the northern areas.

Due to the southern part mainly hills, the rivers that flow from the plateau of Puncak to South into the Java Sea in the direction of North. The largest river is the Ciliwung, divided the city into East and West zones. The other Pesanggrahan River and Sunter.

The River, plus the rainy climate and the old drainage system caused Jakarta prone to flooding. Moreover, the city is sinking gradually each year 5-10 cm, even in the northern coastal area sunk to 20 cm per year. This is also the common status of many municipalities in South East Asia. Manila sinking 9 cm/year, HCM CITY 7, 6 cm/year and Bangkok 2, 5 cm/year.

Contribute to Jakarta to sink gradually also due to sinking from the extraction of ground water. This is common in Jakarta because the majority of the city’s residents get water under the ground from wells. Wells also provide 1/3 of the water needs for the business and industrial activities. This becomes worse by the sheer weight of Jakarta on the rise according to the expansion of the town.

Economic development in recent decades has changed from low-floor urban city into a “forest” on a high rise tower. The weight of the buildings are crushed the weak ground below. The city is sinking down, while increasing sea surges up.

Scientists calculate that every century, sea level rose an average of 20 cm. Forecast of 10-15 years from now there will be many areas of Jakarta will be submerged in the sea water, directly threatening the Habitat of a million inhabitants of the municipality.

The disaster lie in wait

Could not stop the city on a sink, Jakarta focused search measures prevent the State attenuated by seawater. February Islamic storm-2007 has made the Government more determined. This coincided with the storm tide has put a large amount of water from the Bay of Jakarta in the capital. Almost half the area of Jakarta was covered in 4 m of muddy water. At least 76 people were killed and 590,000 people lost homes, damages of about 544 million.

After the storm, several options were put forward, including the migration of population to higher part of the city in the Southeast, or to a different island. The population density of 5,585 km2, indeed, this approach is not easy to implement. A different approach is to simply abandon the North Jakarta.

However, Jakarta is the heart of Indonesia’s economy, accounting for 20% of GDP. Put 40% of the city is the home of nearly 1/2 the population of Jakarta, for the sea is impossible. “If the deserted area in North Jakarta, will lose 220 billion of assets”-Robert Sianipar, a senior official of the Ministry for the coordination of economic issues, said.

Finally, the Government decided to concentrate the solution protects the coast and improving the system of flood drainage channels was downgraded. The Dutch Government agreed to technical support. The height of the previous 32 km long dike was raised in 2008.

However, it does not have the ability to protect the city against a major storm, or even a moderately high tide. When the tide is high in some places, levees are almost hard knob be removed from the water, partly due to the sea water on a higher, due in part to sinking levees on alluvial sedimentary gradual software.

In 2012, the World Bank (WB) warned the flood disaster will soon became a regular in Jakarta and caused serious damage on the economy and society. The WB’s prediction was right when in January 2013, a big monsoon storm caused many parts of the city submerged under 1, 6 m of water.

Garuda wing extended

Not long after, master planned development in the coastal capital (NCICD), also known as the “giant sea Dyke” or “the great Garuda” (by Garuda-like character in Hindu myth is present in the coat of arms of Indonesia, half Eagles and is the God of immortality) is deployed.

Complex worth 40 billion dollars including the wall sure long water 24 km and 17 artificial island has the function to open or close the Bay of Jakarta. With the 40-year construction period, the project using the technology, techniques and experiences of the Netherlands-the highly successful national and world famous the works prevent sea water submerged resistant and polders.

In the back of a giant sea dams will have large parts store of fresh water and many artificial islands. Thus, this project also aims to both reclaimed purpose, creating space and living environment for the people in the municipality.

The great Garuda project perspective.

The construction was started on 9-10-2014. The first phase of the project the great Garuda is building thick wall 1.8 m in the old wall in order to prolong the resistant of Jakarta. Does this city have to 13 rivers and canals. Some Creek flows into the Lake to hold flood water.

A pump station then sucked water from the lake flows into the Bay of Jakarta through a long pipeline of several hundred metres. Need to add many more great lakes to flushing of all rivers and other waterways, including the great flood prevention channel.

However, to get the total area of the Lake up to 100km2 in order to accommodate the large amount of water on is impossible in a crowded city like Jakarta. The great Garuda will solve that by creating a large reservoir in the Jakarta Bay, surrounded by the inner and outer embankment and shore pump to pump water out.

However, the city must resolve a major issue is to provide clean water for most residents and establish the basis of processing the waste to rivers, canals and water reservoirs of the great Garuda project is not contaminated. About techniques and technologies, this project entirely feasible. Great difficulties influence decisions to viability is the capital and the construction of dams combined with urban planning and urban development.

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