by: Soetrisno S.

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1. INTRODUCTION

Groundwater resources have always contributed substantially to the supply of water in Indonesia. Groundwater has been utilized for many centuries, particularly shallow groundwater for domestic purposes. Deep groundwater, however, had only begun to be developed since the middle of the last century, when a deep well was successfully drilled in 1848 at Fort Prins Hendrik, a Dutch fortress in Batavia (now Jakarta). At present, groundwater is a major source of water for drinking, industry and agriculture.

In line with the development of the country in all sectors, the rate of groundwater exploitation increasing rapidly. In the Greater Bandung, the use of groundwater has greatly accelerated conforming to the rise in its population and the development of industrial sector, primarily textile manufactures which consume a relatively huge amount of water.

The abstraction of deep groundwater in Bandung had begun in 1893, in order to supply the European communities. In 1900, 0.5 million m³ deep groundwater has been exploited. Sine then, the abstraction is increasing gradually and starting in 1976 a pronounced figure of groundwater exploitation has been recorded, due to the development of the industrial sector (Table 1).

The increase of groundwater exploitation in Greater Bandung has already caused a negative impact on these resources itself both quantity and quality. In addition the changing environment as consequence of the development, has also brought indesirable effects to the quality of groundwater. Therefore, protection of groundwater in relation with regional planning, primarily land use planning based on environmental geology aspects, is indespensable.

2. IMPACT OF GROUNDWATER EXPLOITATION

Lowering of water level both from the shallow and deep groundwater system due to groundwater exploitation is the direct impact, which is easily observed through observation wells spread out in the Greater Bandung.

In the sixties, static water level of deep groundwater was generally above surface, between 3 and 25 m in the boundary between Bandung plain and hilly area in Cimahi - Cibereum. At present, the above condition has changed, and water level has dropped far below ground surface.

General condition of water level in 1990 as recorded from several observation wells, may described as follows: in the western part (Cimahi - Leuwigajah) where many textile industries are concentrated, water level lies between 20 and 40 m below surface, and 20 - 30 m below surface in central part, whereas in the southern part (Dayeuhkolot) and in the eastern part (Cicaheum - Cileunyi) where many textile industries are located, too, water level lies between 40 and 44 m and 3 - 18 m below surface respectively.

The observations of the last ten years shows deep groundwater level declines 1 - 2 m/year, where the deepest drawdown occurred in Leuwigajah, 2.5 m/year. Cones of depression are observed in Leuwigajah. central part of the city and Dayeuhkolot.

This above condition has considerably changed the recharge and discharge situation in Greater Bandung. During the natural stage, when discharge quantities did not yet exceed recharge quantities, recharge from rainfall infiltration replenished the shallow aquifer during the rainy season over the entire area of Greater Bandung. In the Bandung plain at that time, upward leakage from the deeper aquifers system could occur to the shallow system.

The actual situation that developed due to overexploitation of deep groundwater system primarily in the Bandung plain where discharge quantities exceed recharge quantities, has caused decending groundwater level in the entirely of the Greater Bandung.

Deep groundwater level (piezometric head level) between 20 and 40 m as mentioned above, are generally below the phreatic head (shallow groundwater level) of groundwater nearly everywhere. Consequently recharge to the deep aquifers system in the Bandung plain happens also by vertical downward leakage.

Implication of the above situation is that deep aquifers system is at high risk to pollution from the above system, while declining of water level due to overexploitation will change the hydraulic gradient, thus trigerring the speedy movement of the pollutants from above to the deeper groundwater system. This eventually has led to the deterioration of groundwater quality in Greater Bandung.

3.GROUNDWATER POLLUTION

The quality of groundwater depends generally upon the environment, its movement and its source. In addition quality may be deteriorated as a result of man's activities.

The water quality of the shallow aquifer, conventionally limited to upper 20 - 40 m of the aquifer system, in the Greater Bandung is highly endangered by man made pollution in the densely populated and highly developed areas in the city of Bandung. In the industrial and agricultural areas, pollution also effects the quality of groundwater. However, obviously no contamination to the deeper aquifer system has been recorded so far.

It can be noted there are three sources of groundwater contamination in the shallow system, which are domestic and industrial wastes, and presumably agricultural activities.

• Domestic waste
  Contamination of shallow groundwater by domestic waste has been recorded mostly in the densely populated area of the Bandung city, as result of poor drainage and sewerage. Whereas the improper location of waste disposal in Dago, north of Bandung, downgraded the quality of shallow groundwater occurrence nearby;

• Industrial waste
  Contamination of the shallow groundwater adjacent to the already polluted river caused by industrial waste, has been detected. Since most of industries have no treatment plant for their waste, they simply discharge their waste to the surface water bodies, leading to the contamination of the shallower groundwater;

• Agricultural waste
  The usage of fertilizers, insecticides and pesticides may be suspected as a source of the shallow groundwater contamination.

Since the shallow and deep groundwater plays an important role in the development, adequate measures for protection, both quantity and quality have to be taken.

4. PROTECTION

Protection of groundwater is not merely a concern to the quantity and quality of the resources itself, but also involvement of the regional planning of recharge and discharge areas. This refers to the hydrologic cycle, where the groundwater is just a part of various aspects and its occurence depends upon the geo-bio-physic-socio-economics of the environment. Hence, regional planning also plays an important role in the protection of groundwater.

Measures for protection of the groundwater are based on two aspects, legal and technical.

Legal aspect is a series of regulation and legeslation related to groundwater resources. Among others are the Constitution of 1945, Article 33, paragraph (3); Law 11 of 1974 on Water Resources; Government Act 22 of 1982 on Water Resources Management, Article 6; Regulation of Minister of Mines and Energy 03/P/M/Pertamben/1983 on Groundwater Management.

Technical aspect concerning groundwater protection comprises all steps, which has to be taken based merely upon the hydrogeological knowledge of the respective area.

On the basis of the two above aspects, counter measures were adopted to cope with it, which are as follows:

1. To restrict the extraction of deep groundwater.
   Restriction of licences for industrial use is issued based upon the binding technical recommendation given by Director of Environmental Geology, in order to restore water level.

2. Adjustment of the strata of extraction of underground water
   At present the most prominent aquifers, which have heavily been tapped are from the depth of 100 to 150 m. In areas where the hydrogeological condition permits, extraction from the deeper aquifers has to be conducted.

3. To undertake artificial water recharge into aquifers
   During rainy season, water can be collected from the roofs and injected into infiltration wells, in order to increase recharge into shallow aquifers. However, infiltration wells only can be built in the area where hydrogeological condition is favorable.

4. To work out a plan and regulation for extraction of deep groundwater
   Based on the data and investigation of past years, a mathematical model in the Bandung basin has been established. This model gives scenarios, with wich annual schemes of rational extraction of deep groundwater for the city of Bandung, primarily for industries were compiled, putting forth the optimum allotment plan for extraction at certain periods for different areas and different layers of aquifers.

5. To set-up groundwater protection areas
   Groundwater protection areas address to spatial planning of a certain area in order to protect both quality and quantity of groundwater resources. Therefore, to determine groundwater protection areas, beside hydrogeological condition, actual land use and existing infrastructure has to be considered.

   The difficult task in accomodation the various demands for the use of available space , whilst at the same time preserving the land protecting the groundwater, can only be achieved through an integrated effort embracing local and regional, even national planning. Priorities should be assigned at planning stage and adhered to.

   In this respect the environmental geology has a decisive role, since the possess or are able to obtain information, on the main relevant factors. This include the occurrence and size of economic deposits, soil types, building or construction materials and above all, the availability of groundwater and natural conditions for latter's protection. It is therefore, necessary to compile environmental geological data in order to make it available to planners.

   A series of maps of Greater Bandung among others contains a groundwater protection map. These series are produced by the Environmental Geology for Land Use and Regional Planning Project, a co-operation project between the Government of Indonesia and the Federal Republic of Germany (CTA-108) and is a proven example to convey the regional planning from environmental geological aspect to the planners. These maps accomodated all conflicts of interest of land use, and determine the planned priority based on availability and sustainability of natural resources. This enables the decision maker to forestall new ventures that are contrary to established utilization options or requirements of groundwater resources.

   In view of the dense population and related requirements of intensive land use, it appears not possible to apply efficient protection measures for all occurrences of exploitable groundwater. However, recommendable measures for groundwater quality protection in the Greater Bandung have been set-up (Wagner and Sukrisno, 1991).

   The requirements of groundwater protection in regional planning and land use developments in the Greter Bandung can be formulated:(Wagner and Sukrisno, 1991)

   • No new residential and commercial areas within groundwater protection areas, except an adequate sewerage system is installed; pipe water supply is advisable;

   • New or expansion of industrial areas not within groundwater protection areas, except adequate waste water collection and treatment system are installed, preferably not in areas with restriction for groundwater abstraction;

   • Waste disposal sites preferably not in groundwater protection areas;

   • Traffic (roads, railways, airport) and exploitation of mineral resources in protection areas only after detailed investigations;

   • Deep excavations in protection areas to be restricted or accompanied by protective measures;

   • Conservation of present land use: preferably all presently forested areas and in protection areas with presently prevailing agricultural land use.

   5. THE CONSTRAINTS

   The implementation of groundwater protection measures, however, face several constraints, apart from dense population and competitive land use as already described before.

   There are four constraints which are as follows :

   1. Administrative: in several cases the coordination among sectors related to groundwater has to enhance. There is no regulation which particularly sets up the requirement of groundwater protection areas;

   2. Technical: not enough detailed hydrogeological information, which will lead to determine groundwater protection areas;

   3. Economical: high cost economy required to serve population other than groundwater resources;

   4. Social: unawareness of various groundwater users of the necessity to conserve groundwater resources.

   As groundwater resources are only one part of the components of hydrologic cycle, as mentioned above, to overcome the above constraints, therefore, all efforts concerning groundwater protection have to be taken integrally. The other important thing is that governmment policy has to set-up highest priority for new industries which consume low amounts of water and clean industry.

   6. CONCLUSION

   The suitability of groundwater resources for various purposes in the Greater Bandung can, on longterm basis, be sustained only if adequate measures for protection of the groundwater are conducted.

   Groundwater protection has to be taken in an integral way and backed-up by favorable policy on low consuming water and clean industries.

   The difficulties and high cost of treating dirty water and the impossibility, even in the medium term, to rehabilitate polluted groundwater system should encourage all parties to understand the vital need of groundwater protection in order to maintain the good quality of our groundwater resources.

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   Reference: 

   1. Hahn, J., 1991, Balancing the Requirements of Land Use and Groundwater Protection in Rural Areas, International Hydrological Programme, IHP III Project 10.6., UNESCO, Paris.

   2. Wagner W., and Sukrisno, 1991, Groundwater Quality Protection in the Northern and Eastern Parts of the Bandung Basin, with Conclusions for Land Use and Regional PLanning, Directorate of Environmental Geology - German Environmental Geology Advisory Team in Indonesia, Bandung.

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