Facts: related to issues of Jakarta is Sinking
|Sinking||7,5 cm – 25 cm per year|
|Number of rivers||13|
|Area Size||4,384 KM2|
|Area below sea-level||40%|
History of Jakarta
The history of the city of North Jakarta goes back as far as the 4th century. From the kingdom of Sunda, the Bantan Sultanate, the Dutch East India Company and the Japanese occupation. Jakarta is now one of the top 5 fastest growing cities in the world. https://en.wikipedia.org/wiki/History_of_Jakarta
Jakarta has a long history of floods; floods triggered by heavy seasonal rain documented as early as 1699. And more recent since 1996 Jakarta is experiencing also tidal floods from the sea.
2007 The biggest flood in 3 centuries; A high tide topped over the seawall and sea water rushed through the streets creating high waters from 1.5 meters up to 7 meters in some areas. Affecting more than 2.6 million people, forcing 340.000 people to flee from their homes. Over 70 people died and outbreaks of disease affected over 200.000 people.
Jakarta, with more than 20 million residents, making it one of the world’s five most densely populated cities, is on the verge of drowning. Geographically, Jakarta lies in the delta of 13 rivers with 40% of its land below sea level, which makes it very vulnerable to flooding. If nothing is done, it is expected one third of the city will be submerged in water in 20-30 years’ time.
Land subsidence & deep ground water extraction
The city is sinking between 7,5 cm – 25 cm per year. Ongoing economic development and a growing population are causing an excessive and unregulated extraction of deep ground water (200 m). About 75% of Jakarta’s residents rely on groundwater, because piped water is more expensive, not available or too dirty. Water levels drop faster than they can replenish themselves, causing the soil to compact, and the city to sink further below sea level.
Preservation area coast and green spaces
With a growing population, green spaces – the natural drainage system -disappear along the coastline and riverbanks.
Waste & pollution
A large part of Jakarta’ s daily household waste is dumped in the water; clogging the pumps and obstruct and pollute the waterways. Rainfall will intensify over the years because of climate change, with decrease of river volumes, and green spaces for rivers to expand; more flooding.
Rising sea levels
The biggest threat is coming from the sea. Jakarta relies on an existing 40-year-old seawall to keep the City safe from the Java Sea. This 30-kilometers seawall is also sinking at an alarming rate. Structure slips under the waves, offering little protection against another big storm surges, or even a moderately high spring tide. Both because the sea is rising and because the wall itself is sinking into soft alluvial sediments. The next extreme high tide is calculated to be in 2025, however, before this date more tidal floods will already occur.
Overview of measures against flooding
With its long history of flooding, some measures have been taken: the height of the present seawall was raised in 2008, construction and fortification of are still ongoing, reconstruction and capacity improvement of pumps, completion of East Flood Canal construction and the evicting of settlers along rivers/lakes and river widening to create green areas.
Though, none of these measures are sufficient to stop Jakarta from sinking.
Drinking water policy
To stop the city from sinking strict measures are needed: regulations limiting the amount of deep groundwater extraction, stop illegal pumping wells, extend access of piped water system and improvement of water quality.
To reduce the dumping of solid and household waste in the rivers, proper waste management is needed such as recycling plans and large scale garbage collection.
The Great Garuda
After the 2007 floods, a Dutch team of water experts, engineers and Dutch and Indonesian government officials have been working on a strategic Master plan also known as the ‘Great Garuda’ for its resemblance from the air to the mythical bird, Indonesia‘s national Symbol. A coastal development and flood defence strategy resulting in a large scale flood mitigation and land reclamation project. Ultimately this should lead to the construction of a 36 kilometre long dike ‘The Giant Seawall’ in the Bay of Jakarta. This plan is a proposal; it is still under revision and the outcome if and how it will be executed is still uncertain.
Over the years various solutions have been mentioned; relocating the whole city to another island or abandon North Jakarta. Both ideas were dismissed.