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to HydroWeb Homepage Introducing Indonesia
Indonesia is an archipelago located between two oceans, the Pacific and Indian, and two continents, Asia and Australia. The whole territory consists of 13,677 islands of which about 6000 are uninhabited. About 70% of its 190 million population live on Java, its fifth largest island. Indonesia lies between 95o and 141o east longitude and between 6o north and 11o south. Yearly rainfall in varies widely between 700 mm on central parts of Timor to 7000 mm on western parts of Java, while yearly evapotranspiration is within the range of 1,200 to 1,400 mm.
Main Hydrologic Problems and Issues
Watershed management
It used to be that shifting cultivation of our traditional farmers was regarded as the main culprit for the degradation of Indonesian watersheds, but it was soon realized that uncontrolled logging activities have deteriorated most of our fragile tropical forests and thus changed the hydrologic behavior of our main rivers in Sumatra, Kalimantan, and Irian Jaya (Indonesian part of Papua). In Java, the degradation of many watersheds is partly associated with population pressure, but mostly due to unsuitable farming systems such as growing vegetables on highly-sloping terrain. To prevent further degradation of Indonesian watersheds, the government launched a national program to rehabilitate 22 priority watersheds (in 1984) and 17 more watersheds since 1989. In the priority watersheds, improvements in farming systems and forest cover conditions are conducted. Since 1994, the program has concentrated its effort toward improving farmers and other watershed users participation in the program.
Floods in Jakarta and the surrounding areas
Floods occuring almost every year in Jakarta are still a major unresolved problem. Beside hydrological reasons such as its geographical position in a flood plain of 13 rivers with high rainfall watersheds (more than 2000 mm yearly rainfall) and backwater effects of high tides from the Jakarta bay, the flood problem is worsened by population pressure and socio-culture problems. In this metropolitan city, it is still common to regard rivers as a 'big garbage bin'.
In modern times, efforts to alleviate the flood problem in Jakarta started in 1919 with the construction of two flood gates in Manggarai dan Karet. The hydraulic structures were designed by Professor Ir. van Breen. Since then many more structures were built until a thorough masterplan for flood prevention was finally prepared in 1973 by the Government of Indonesia assisted by a Dutch consulting firm. As usual, implementing the whole masterplan has been difficult, many hydraulic structures have not been built, and river maintenance fails to catch up with fast development of the ever-increasing population.
This year the preparation of another masterplan was started with the help of the Government of Japan. The target year for this flood control master plan is 2025. The writer participates as a hydrologist in the environmental impact assessment of the masterplan.
Land conversions for residential real estate
The development of residential real estate surrounding Jakarta has replaced thousands of hectares of irrigated rice fields, small lakes and other forms of vegetation-covered lands. Some residentail developments are even built on water catchment areas. This new type of land use has many adverse hydrologic impacts. Suggestions to improve recharge capacity of lands, for example, by building individual recharge wells for each building structure or porous pavements for parking lots are normally accepted only on paper (in Environmental Impacts Assessments documents) and are rarely implemented. The immediate impacts of such land conversion takes the forms of floods and deterioration of groundwater sources.
Protection of drinking water sources
It is estimated that municipal water supplies in Indonesia could provide drinking-quality water to only 43% of inhabitants. In Jakarta, that level of service is even less than 40%. Municipal water supplies in Indonesian western islands are from surface water, while those in eastern islands (Bali, Mollucas, Irian Jaya and Nusa Tenggara) are from groundwater sources. Apart from treatments to bring the water into drinking quality, there are very limited programs available to protect the water at it sources. No delineation of protection zones for any water sources has been prepared.
As in other countries in the Asian Pacific, Indonesia is also experiencing a boom in the package (mineral) water industry. Deterioration of water supply quality and improvements in the economy are regarded as the main reasons. Most package water producers uses springs or deep wells as their water sources. Ironically, most if not all package water producers here do not have comprehensive programs to protect the water sources. Many have to abandon their water sources due to deterioration in water quality of an anthropogenic nature.
Water quality degradation from industrial activities
This problem is more concentrated in Java than other Indonesian islands as this island is the most populated and also industrialized. While groundwater quality degradation could occur in this situation, more attention is given to surface water protection. Since 1978 the government has launched PROKASIH (Indonesian abbreviation of Clean River Program) aiming to reduce the pollutant load of rivers, improve river water quality and improve institutional resources to protect rivers. At the current stage the program is focused on controlling pollution from industrial wastes. A 1994 report of the program showed a considerable success in reducing the pollution load, but the improved quality of 27 rivers was not obvious as industry was not the only source of pollution to rivers. This PROKASIH program won the American Society of Environmental Engineers award for the management category in April 1992.
Acknowledgements
The help of Engineer Aries Diana in collecting the data for this article is greatly appreciated.