Lifting up Jakarta?


Lifting up Jakarta?

Selamat siang para pembaca,

Beberapa hari lalu, seorang kolega fisikawan dari USA mengusulkan solusi yang lumayan unik terhadap problem DKI Jakarta.
Idenya adalah mengangkat seluruh DKI sampai di atas level muka air laut.
Meski kabarnya metode ini pernah diterapkan untuk kota Galveston di Texas sekitar tahun 1900an, namun kok sepertinya kurang pas untuk problem Jakarta yang ruwet dan luas.
Memang metode "jacking" hidrolika bisa diterapkan untuk  bangunan atau gedung bertingkat rendah, misalnya sampai 2-3 lantai.
Namun kalau mau jacking seluruh kota, apakah tidak ruwet ya?
Sepertinya, mendingan kita kembali ke normalisasi dan naturalisasi dan wadukisasi saja ya.
Namun supaya jelas apa yang dimaksud penggagasnya, berikut saya lampirkan e-mail beliau.

Bagaimana pendapat Anda?

Versi 1.0: 14 Januari 2020, pk. 12:33
VC

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Fixing Jakarta ~ Raising an entire city higher above sea level.

by Robert Neil Boyd, PhD

Lifting an Entire City
Raising the height of the entire city of Galveston, higher above sea level was complicated.
The work began in December 1903 and was done in quarter-mile square sections, each about 16 city blocks in size. Each section in turn, as it was being raised, was enclosed in a dike, to keep water out.
In addition to buildings and structures, all the utility lines within each dike, all the sewer lines, water and gas lines, streetcar tracks, fire hydrants and telephone and telegraph poles, all had to be lifted. Fences, sidewalks, and outbuildings, also had to be repositioned.
Some of the city of Galveston's wooden frame structures, had previously been built on stilts because of the city's history of periodic flooding. Many of these older structures were high enough above the water line to accommodate the new increasing height in ground level.
All the buildings that weren't already on stilts – about 2,000 buildings – were raised with jacks. Even the 3,000-ton St. Patrick's Church was lifted five feet into the air with 700 jack-screws.
Sand for the fill which was used to raise the land level, was dredged out of an area between the jetties at the entrance to Galveston harbor, which had the additional benefit of deepening water depth of the approach to the Galveston harbor.
To transport the fill-in material to the areas that were being raised, a selected contractor built a canal 20 feet deep, 200 feet wide, and 2 and 1/2 miles long, through the residential district. About 350 houses had to be temporarily relocated so that the canal could be dug out.
A slurry of water and fill sand, dug out of the harbor channel by dredges, was sailed in barges, down the completed canal, to discharge stations, from which the mixture was pumped into the area, to lift it to the desired level. The water in the slurry was then drained away, leaving the sand behind. New foundations were constructed for the buildings on top of the new fill material, and structures were then fastened to their new bases, which were now much higher above sea level.
While all this work was being done, city people walked about on catwalks as high as eight to ten feet in the air.
The area immediately behind the seawall was raised just over 16.5 feet, giving the seawall a solid support. The grade decreased one foot for every 1,500 feet west to Galveston Bay, so that the city's streets drained into the bay. A side benefit of the grade raising was that the city's sewer system, which had never worked right, finally had enough slope to enable it to operate properly.
When the job was finished in 1910, 500 city blocks had been raised from a few inches to more than 16 feet by the use of 16.3 million cubic yards of sand.
Since then, in spite of the impacts of many large hurricanes, the city of Galveston has never been flooded again.
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I suggest that a similar land-raising project could be done for the Jakarta region. It would be expensive, but many of the problems of the region could be mitigated or entirely removed.
Probably this sort of thing has been considered before, but it seems to me to be the best solution, "given that I do not know the physical topological difficulties that would be encountered by a land-raising project in the Jakarta region."

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