Senin, 18 Februari 2013

Living in harmony with natural Jakarta


Living in harmony with natural Jakarta
Wiryono   A Lecturer at the University of Bengkulu’s Forestry School
JAKARTA POST, 12 Februari 2013


It is ironic that many high-level government officials, including President Susilo Bambang Yudhoyono, seemed taken by surprise by the major floods that inundated much of Jakarta. The President and his Cabinet held an emergency meeting to figure out how to avoid flooding in the future. 

They apparently forgot that Jakarta is no stranger to such problems and major floods have struck the city twice in the last 11 years. Even during the colonial era, Jakarta experienced major floods.

Naturally, Jakarta is vulnerable to flooding. It lies in a lowland area, with about 40 percent of its area situated under sea level. Gravity pulls water down and settles it in the lowest area. High tides will result in the inundation of low areas near beaches. 

Furthermore, 13 rivers have estuaries in Jakarta. Heavy rain in Bogor in the south causes an overflow of water along the river bank and finally in areas surrounding the estuaries. 

Considering the natural setting of Jakarta from a hydrological point of view, the natural and cheapest way to avoid floods is to let nature take its course. In other words, leave the low lying area as the water sinks and do not build houses in these areas. 

Settlements along riverbanks must be relocated. According to Presidential Decree No. 32/1990, riverbanks are protected areas upon which no construction can take place.

If we let low lying areas be wetlands, it does not mean that we are wasting natural resources. Wetland is not wasted land. 

Permanent, relatively deep wetland, such as lakes, can be developed for fisheries and recreation (fishing, canoeing and wild life sightseeing). Periodic and relatively shallow wetlands can be developed as rice fields.

In the event that we really have to build houses in flood-prone areas, the houses must be specially designed to anticipate floods. 

Several international donors and NGOs have designed flood-adapted houses for flood-prone areas in Bangladesh. Some traditional communities in Indonesia living on major riverbanks have also created flood-adapted houses. 

We may create polders in low areas near the beach, like in the Netherlands, but they are costly and not completely safe. On the nights of Jan. 31 and Feb. 1, 1953, a combination of storms and high tides destroyed many dikes built to prevent areas below sea level in the Netherlands. As a result, as many as 1,836 persons were killed and 70,000 more displaced.

To live in harmony with the hydrological setting of Jakarta, we must let low lying areas be open spaces and limit construction. What we have done, however, is just the opposite. We have drained wetlands and turned them into settlements and commercial areas. We have built and continue to build many gigantic buildings, putting heavy pressure on the ground. 

Furthermore, we pump out the underground water and turn open land into concrete, preventing the refilling of ground water. As a result, every year the ground in Jakarta subsides, increasing the area of low land vulnerable to flooding. 

To make matters worse, development in Bogor has reduced open areas, reducing water infiltration into the soil and increasing run off, or water flowing on the surface.

The government has plans to prevent the future flooding of Jakarta, such as finishing the construction of the east and west flood canals, fortifying dikes, creating water infiltration wells in every office, relocating residents living in riverbanks, and perhaps most ambitious, creating deep tunnels. 

The government has also asked West Java province to rehabilitate the water catchment area in Bogor. These plans are good and will certainly alleviate the problem. 

But the most important thing is implanting the idea that Jakarta has a limited carrying capacity that must not be exceeded. The population of Jakarta must be reduced, or at least, kept at the same level. 

Population growth is the root of environmental problems, including flooding. More people need more land for housing, which results in the occupation of riverbanks and other low laying areas. 

More people produce more waste, which may be thrown into rivers, reducing the speed and volume of water flows. More people also need more goods, resulting in the establishment of large shopping center buildings, putting heavy pressure on the ground and covering a large area of land with concrete. 

The government has to create job opportunities outside Jakarta to prevent migration into Jakarta.

We must also stop, or at least slow down, land subsidence. One cause of land subsidence is the decrease of ground water due to large withdrawals and limited replenishment. 

The permit for ground water withdrawal must be limited and strictly controlled. The plan of the government to order every building owner to construct water infiltration wells is a good idea. 

We must also reduce the area of impervious land surfaces. Parking lots, for example, can be made from perforated concrete, allowing water to infiltrate the ground. Another cause of land subsidence is the construction of large buildings. We must stop constructing extremely large buildings.

It is impossible to defy the laws of nature. If we let Jakarta’s population grow and we continue to construct gigantic buildings, flooding will only get worse. 

Several years ago, some experts predicted from computer modeling that much of Jakarta’s area would be permanently inundated in 2030. 

Living harmoniously with the natural setting of Jakarta may compromise economic growth, but not necessarily the quality of life. If we carry on with business as usual, we may gain economic benefit in the short term, but in the long run we will suffer tremendous economic loss because Jakarta will be inundated permanently and will need to be abandoned. ●

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