Our Wetlands: Can we really live without them?

By Imam Soeseno

JAKARTA (JP): Last March, for the second time, the region in the vicinity of Professor Sedyatmo Highway was flooded due to the incidence of a rather high rainfall.

When was the first flood occurrence? It was only February 1993.

Some sources say never before they experienced such floods. This first flood happened not long after wetlands were destroyed to make way for construction.

Many think that this "conversion" of wetlands is the cause for the new string of floods. The fact is that 30 hectares of wetlands have been filled up for the purpose of erecting factories. The reclamation was then continued with a much-debated development of a luxurious Pantai Indah Kapuk residential and commercial site. This site has consumed 100 hectares of wetlands and will take some 832 hectares more.

The occurrences of floods is a failure of the hydrological system caused by wetlands reclamation.

Therefore, we must now reevaluate the role of the 40 million hectares of wetlands spread over in our four main islands. We must also decide whether these regions can be classified as unprofitable areas that are economically and ecologically disposable.

Ecological functions

The word 'wetlands', an invention of the age of ecology, is a relative newcomer to the language and requires some sort of explanation. It used to be that most people were content to speak of marshes and swamps without bothering the difference between the two.

A marsh is a wet place with herbaceous vegetation, while a swamp is a wet place dominated by shrubs and trees. There are so many different kinds of each, namely bogs, sloughs, floodplains, estuarine marshes, to cite just a few. The cover-all term for all of these terms is 'wetlands'.

According to the data provided by the Directorate of Swamps of the Ministry of Public Works, we have almost 40 million hectares of wetlands spread over on four main islands of Sumatra, Java, Kalimantan, and Irian Jaya.

All of them are open for reclamation, mainly for agricultural purposes, under the coordination of the directorate. The reclamation, according to regulations, has to be based on the concept of sustainable development.

In its soul, though, the regulations encourage reclamation in the hopes that those 'wastelands' might soon bear the fruits of sustained agriculture.

Nobody would argue that wetlands is a form of rich and complex ecosystems. We all realize wetlands are producers of life, some being equal in output to a same-size chunk of tropical rain forest. They are places of plenty; it would be easy to find numerous species of birds, fish, and microbes.

A bakau forest or mangrove has at least 60 plant species and more than 2000 species of aquatic and terrestrial fauna. Certainly, you have also an understanding of the ecological term "biological diversity", then wetlands could claim to be on the most top list to be preserved.

Richness

With their richness of plants, wetlands lock up large amounts of carbon -- mostly in the form of peat -- thereby preventing it from entering the atmosphere as carbon dioxide. This compound is the principal culprit in global warming.

So who cares? Certainly not the utilitarian who eats no fish, eschews bird watching, scoffs at the concept of biological diversity and regards global warming as an elitist scam. Still, do swamps have any value for those people too?

I will let the biologists explain how we have lost invaluable fishery potential due to our indifference in loosing our coastal wetlands or how, in 1984, the outbreak of malaria took place in a village near Cilacap (southern Java) due to the lost of the region's mangroves. In this matter I am only a laity and as an hydrologist I would pursue the discussion toward the problems of water quality and availability.

People need water at the right quality and also quantity. In the context of discussing wetlands, the problem is, people need protection from too much water in the wrong places at the wrong times, that is, floods. How do wetlands have something to do with floods?

Wetlands serve the environment as the so-called retarding basin. On the times of high tides, streams and rivers have their flows slowed due to lower hydraulic head gradient. The coastal wetlands take up all excess water. Inland marshes sponge up runoff, thus reducing flood crests downstream.

Flourishing in the middle of river meanders, floodplain forest serve as reservoirs during times of high water. Instead of letting the water rush downstream, flood water pools behind natural levees and in sloughs and oxbows, and is then slowly released. Not only the swamp trees slow the river's water speed, the thick woody vegetation also traps sediment.

As natural purifiers, small swamps with tall trees at the center act to eliminate wastes carried in water. Fed domestic sewage and agrochemicals, the tree roots remove most of the harmful nitrates and phosphates, binding them up in mud and tree roots. However, it must be acknowledged that this function may became overloaded as our water is more and more polluted.

Sacrifice

Jakarta used to be rich not only in coastal wetlands but also in inland wetlands as well, which were preserved and guarded fanatically by our ancestors. Now we may sacrifice all of them in the name of development.

In their place has sprung expensive mansions. Only luxurious buildings could afford the expensive costs of wetlands reclamations.

But at the end, the loss of retarding basin functions has caused many places like Bintaro, Pondok Aren, and Jurang Mangu to experience floods for the first time.

Recently, there has been a movement to build artificial retarding basins in lieu of their natural counterparts in efforts to alleviate the flood problems. It is such an irony that we, all of the tax payers who are the innocent party in such cases, have to pay for their construction. If those wetlands still existed they would provide that service free, for all of us.

It is interesting to discuss the case of floods happening on the nearby areas of Pantai Indah Kapuk (PIK) residential estate. This luxurious site employs the well-known "polder system" imported from the lower-than-sea-level country, the Netherlands.

In brief, the housing estate is lower than the average high tides, therefore a network of dams becomes necessary. The former wetlands functioned as a retention basin, but the PIK now has built a replacement for this, the so-called "longstorage" completed with pumps.

With this artificial reservoir, the water excess from PIK site could be temporarily collected in the storage system and released to the Cengkareng Drain.

Failure

The occurrence of flooding might possibly have been caused by PIK's failure to keep the functions of wetlands it has previously reclaimed. By building a network of dams for the polder, PIK has disconnected the reclaimed wetlands from the natural reservoir system of the region. This way, PIK has reduced the water retention capacity of that natural reservoir as much as the area of wetlands it acquired.

It is completely unacceptable to build its so-called longstorage system while disconnecting the system from the surrounding wetlands! It used to be that the wetlands in the region, some in the form of brackish-water ponds, were interconnected by networks of small channels.

The increase of the water level in any place could quickly and easily be distributed over the whole region. Not any more with the development of PIK.

It is absolutely true that we should not arbitrarily place the value of wetlands above everything else. However, comprehensive studies on the role of certain site toward its broader environment could help preventing failures in the hydrological system. As a hydrologist I am sure the failure to asses these problems have increased the occurrences of floods in the area.

The writer is a hydrologist and an environmental impact assessor.