Minggu, 10 Februari 2013

Frequent cases of flooding reduces Jakarta to third-world city


Frequent cases of flooding
reduces Jakarta to third-world city
Tri Harso Karyono ;   A Professor of Architecture and Author of “Green Architecture: An Introduction to the Knowledge of Green Architecture in Indonesia”
JAKARTA POST, 09 Februari 2013


The recent flooding in Jakarta should not have had such a severe impact had the city’s authorities anticipated the disaster, which occurs annually during rainy season.

There are three main aspects associated with the cause of flooding in Jakarta: Global, regional and local. In the global aspect, Jakarta and all coastal cities in the world face a high potential of flooding due to global warming. 

Girardet and Mendonca state in their book, A World Renewable Energy, Ecology, Equality (2009), that about 600 million people worldwide living on small islands and in coastal cities, such as Jakarta, are faced with a serious threat of flooding as the sea level continues to rise due to the melting of polar ice flows due to global warming. 

From the regional point of view, Jakarta’s flooding resulted from large amounts of water from upstream rivers in West Java that flowed across the capital. 

Deforestation in the headwater regions because of development of farms, plantations and housing has reduced rainwater absorption, sparking massive water flows to lower areas and, hence, the flooding in Jakarta. 

To avoid the floods, there is a plan to develop artificial lakes to act as water reservoirs along the West Java border outside Jakarta to take the brunt of the overflowing river. The West Java authority is only reluctantly providing land for this purpose. 

In many developed countries, inland waterways, such as rivers, fall under the control of a central or regional agency, instead of the local government areas in which the rivers are located. 

England and Wales have a number of so-called regional water authorities that manage things like water treatment and land drainage. 

To deal with the overflow of rivers or lakes, these agencies do whatever they can to avoid serious flooding, such as constructing artificial lakes near rivers. 

According to this concept, rivers are not possessed by local authorities, as they were in the past, but by different water authorities that answer to the central government. If a similar system was applied here, then the current dispute between Jakarta and West Java would be overcome by the agency.

The third cause of Jakarta’s flooding is the local factor. Many urban experts argue that the lack of open spaces and green areas in Jakarta is a source of the floods, as rainwater cannot be absorbed by the ground surface. 

Being an urban area, the city’s ground surfaces are primarily covered by hard materials in the form of buildings, roads, parking lots and other amenities. 

However, the main purpose of greening the city is not to absorb rainwater, but rather to reduce its air temperature. 

Increased vegetation would reduce the “hot urban-island effect” in the city. With lower air temperatures, a tropical city can reduce its energy consumption for cooling, and become a low-energy city.

Other than fulfilling an aesthetic aspect, greening a city also helps to absorb carbon dioxide and dust. Plants need carbon dioxide to grow. Measures to “green the city” can be implemented anywhere. 

They do not have to be at ground level only; green areas can also be established on rooftops and on a building’s walls and balconies with potted plants. 

The main idea of greening is to minimize the amount of hard material being exposed to the sun, so that the penetration of solar radiation can be kept to minimum. 

With heavy rainfall, it is not logical to expect rainwater in tropical cities like Jakarta to be absorbed by the ground surfaces. Countless cities in the world that are dominated by hard ground surfaces like concrete and asphalt remain free of flooding despite heavy rains.

The rapid growth of Jakarta has eradicated many green spaces, seeing them replaced by buildings, parking lots and roads. Rainwater that falls on hard surfaces must be able to flow through water channels to lower destinations like canals or rivers, ultimately ending up flowing out to sea. This can be done systematically by means of an integrated drainage system. 

Unfortunately, Jakarta does not have an integrated drainage system and even lacks appropriate water channels. Old channels, built in the 1960s are maintained to this day, although they are no longer sufficient to accommodate the current levels of rainwater. 

Since the ground surfaces are almost entirely covered by concrete and asphalt, the runoff rainwater becomes 10 times greater than before and, consequently, inundates roads and paralyzing traffic.

Constructing an integrated drainage system is the key to overcoming Jakarta’s floods. Although the entire surface of the city is covered by concrete and asphalt, the city will not be flooded if it is well equipped with an integrated drainage system. 

All the runoff water would be circulated accordingly by the water channel and directed to the sea. The dimension of the channels is also an important consideration. 

The water channels should be sufficiently large to accommodate the runoff water and so avoid overflowing water that causes flooding. 

Beside an integrated drainage system and an increase in the size of water channels, there needs to be an ongoing program to dredge sediment from the city’s rivers, canals and lakes. 

The ability of these urban waterways to contain runoff rainwater has markedly declined in recent years due to sedimentation. 

Many high-rise, glass-box buildings have been erected in the capital, replacing a number of old buildings. Architects argue that the new architecture improves the city’s aesthetic look. Sadly, all the new buildings are devoid of historic interest which, in turn, makes the city a less attractive destination for tourists. 

As a capital city, Jakarta requires tough calculations to build. A utilitarian grand plan is much more important than the aesthetics of the city. 

Although Jakarta is adorned with tall buildings that presumably seem opulent to visitors and Indonesians from more remote regions, the frequent floods that have hit the city only strengthen the argument that the capital is little better than a third-world city; a city with no integrated utility system. ●

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