Contents - Previous - Next


This is the old United Nations University website. Visit the new site at http://unu.edu


Morphogenesis of the northern coastal plain of west Java between Cirebon and Jakarta: Its implications for coastal zone management

P. E. Hehanussa and F. Hehuwat

Introduction

Geomorphologically, the province of West Java can be divided into three zones: the northern coastal plain, the volcanic backbone, and the southern coastal area. There is not much coastal plain on the south coast, the land-sea boundary usually being represented by cliffs or hilly to mountainous country rising directly from the sea. The area is sparsely populated. The volcanic backbone, forming the mountainous part of the island, represents the results of volcanic activity throughout the Quaternary, which was characterized by continuous shifting of the eruption centres. Consequently, a number of volcanic belts can be distinguished, active at different stages of

Quaternary history. Interspaced with the volcanoes, a number of plains of different origin can be distinguished, the most conspicuous being those which represent former intramontane lakes (the plains of Bandung and Cianjur). Population density varies a great deal in the volcanic province, ranging from very dense in the intra-montane plains to sparse in the rugged mountainous parts. At least half of West Java's population occupies the northern coastal plain, which represents slightly less than one-third of the total land area of the province.

In the discourse to follow, an analysis of the morphogenesis of the coastal plain is attempted and its implications for the development efforts of the area are discussed.

FIG. 1. Shallow groundwater distribution in West Java

FIG. 2. Coastal development in West Java (Arrows indicate accretion, dots indicate abrasion)

The Northern West Java Coastal Plain

Physiographically, the coastal plain can be divided into:

  1. the alluvial plain, which also includes the upper deltaic plain, and
  2. the coastal plain, in which we distinguish deltaic and inter-deltaic regions.

The landward limit of salt water intrusion can be used as a division between the two units (Fig. 1), although they grade into each other. As the tidal range along the northern coast of Java is generally less than 1.0 m, the configuration of the coastal plain has been, for the larger part, determined by the main fluviatile systems in the area. Superimposed upon these alluvial processes were the effects of eustatic movements and the regional geological structure, which, for the most part, reflects the underlying Plio-Pleistocene structural grain, of which some elements continued to be active in Recent times (Hehuwai 1972). The main rivers debouching into the Java Sea in the area between Cirebon and Jakarta are from east to west: the Cimanok, Cipunegara, Citarum, Ciliwung, and Cisadane.

The result of the interaction between the riverine and the marine systems has resulted in a coast which is generally prograding at rates varying from a mere 3.6 m per year for the Angke distributary of the Ciliwung, to an astonishing 204.0 m per year for the Cimanuk Delta (Fig. 2). The coastal types indude the deltaic areas which can be divided into distributary lobes or fans and inter-distributary bays, and the inter-deltaic areas, in which we can distinguish between straight barrierbeach stretches and the embayments.

Stratigraphy of the Northern West Java Coastal Plain

Detailed investigation of the Quaternary stratigraphy of the coastal plain is still lacking, but a preliminary stratigraphic subdivision based on water-well logs has been established for the Jakarta artesian basin (Soekardi and Koesmono 1973), in which nine lithologic units have been distinguished (Fig. 3). The division was made using key horizons (clay layers, quartzsand beds, etc.), marine fossil fragments, and groundwater characteristics as the distinguishing criteria. The thickness of the Quaternary in the Jakarta artesian basin generally exceeds 250 m and locally it exceeds 300 m. Attempts have been made to correlate the stratigraphic units with the eustatic rise and fall of the sea level during the Pleistocene, but in the absence of radiometric dates, these attempts are not too reliable. Three main sediment assemblages make up the Quaternary section of the coastal plain, namely:

  1. marine sediments, consisting of greenish to bluish grey clay, quartz sand and black sands, and mica-rich sands, all frequently associated with fossil fragments;
  2. fluviatile sediments, ranging from conglomerate to clay, whereby the finer sediments are sometimes carbonaceous; and
  3. volcano-clastic sediments. Some of the marine intervals can be correlated over large distances, giving the impression that these intervals are associated with widespread transgressive events.

Recent Sedimentation

To get a better understanding of the mechanisms and processes involved in the formation of the coastal plain, studies in recent sedimentation have been carried out in the Cimanuk Delta area (Hehanussa etal. 1976) and in Jakarta Bay (Siregar and Hadiwisastra 1977).

Cimanuk Delta

Based on the Ethology and faunal content (mainly foraminifera and ostracods) a number of units can be distinguished, namely (Fig. 4):

  1. the "chenier-plain" sands, associated with the deltaic system,
  2. the "barrier-sands" of the interdeltaic region,
  3. the "mouth-bar" sands,
  4. the "inter distributary bay" and "delta-front" silts, and
  5. the "pro delta" clays.

The faunal assemblage does not reflect only the Ethology of the sub-stratum; it is also dependent on such factors as salinity, water depth, I;ght penetration, and temperature. The palaeontological and lithological data obtained from this study have been used to assign a facies interpretation to the sedimentary sequences encountered in water-well logs of the region,

FIG. 3. Stratigraphic division of Jakarta artesian basin

FIG. 3. Stratigraphic division of Jakarta artesian basin - continue

FIG. 4. Depositional environments in the Cimanuk Delta

FIG. 5. Biotope distribution in Jakarta Bay, January 1976 1. Embayment biotope 2. Transitional biotope 3. Open shelf biotope

Jakarta Bay

The study of Jakarta Bay proceeded along the same lines as the Cimanuk Delta study, but it was confined to the offshore area. This study also had an additional objective, which was to examine changes in the nearshore environment as a result of different climatic conditions (rainfall and wind direction). Two main biotopes have been distinguished in Jakarta Bay, the "open shelf" and the "embayment" biotopes (Fig. 5), and during the rainy season it is possible to distinguish between an "inner" and an "outer" embayment biotope (Hehuwat 1977).

Environmental Implications

From the foregoing discussions it can be seen that the coastal plain of northern West Java was formed by prograding sediments of deltaic and inter-deltaic facies. The spatial arrangement of the various facies is the resutt of a preexisting geologic structural grain, upon which there has been a delicate interplay between the river and the sea systems. Any man-made alteration such as the destruction of the mangrove forest, the dredging of sand from the river channel or from the beach, or the building of structures will disrupt the existing balance. This can result in a coastal plain in which different lithologies ( with different physico-chemical characteristics) are in juxtaposition in both the horizontal as well as the vertical sense. Development of such an area should take into account all these factors.

We will here focus on two aspects, groundwater and soil/ sub soil characteristics.

Groundwater

The Jakarta artesian basin produces groundwater from aquifers at different depths. According to their depth of occurrence we can distinguish the following categories of aquifers (Soekardi and Purbo-Hadiwidjojo 1979): A-up to 60 m, B-between 60 - 150 m, C-between 150 - 225 m, D-exceeding 225 m.

FIG. 6. Salt water encroachment in the Jakarta artesian basin

FIG. 7. Piezometric surfaces of wells in the Jakarta artesian basin

Groundwater is only produced from the aquifers A, B, and C, as the water of category D is usually mineralized. Each category furthermore has its own groundwater characteristics: Category A: salty north of a line that runs from Tanah Abang to Klender; south of this line the content of Fe and Mn is rather high, usually exceeding 0.3mg/l. Specific capacity varies between 50 - 100 I/minim drawdown. Category B: better quality groundwater, but with a high organic content, in excess of 10 mg/l. Specific capacity is small, and varies between 30 - 70 I/min/m drawdown. Category C: the most important water producer; quality in general is good and the specific capacity is between 50 - 100 I/minim drawdown.

It has been estimated that the groundwater potential of the Jakarta artesian basin amounts to 39 million m per year, but there are indications that the actual production exceeds the sustainable yield.

It has been estimated that the groundwater potential of the Jakarta artesian basin amounts to 39 million m per year, but there are indications that the actual production exceeds the sustainable yield. Excessive utilization of this resource results in salt-water encroachment and the lowering of the piezometric surface (Hehanussa 1979). Before the Second World War, salt water was only encountered in wells in the coastal zone at depths of less than 60 m, while today, aquifers of the B category are known to produce salt water (Fig. 6). A notable lowering of the piezometric surfaces can be observed from aquifers in the B and C categories (Fig. 7). In the foreseeable future this deterioration is bound to continue, because of the continuing decline of forest cover in the hinterland, the extension of the wet-rice-field acreage, and the spread of urbanization of Jakarta southward, all of which will result in diminished recharge of the aquifer system.

FlG. 8. Engineering geologoc man of Jakarta-Bogor area

Engineering aspests

The different mechanisms of sedimentation which created the coastal plain of northern West Java gave rise to different subsoil characteristics, as is shown on the engineering geological map of the Bogor-Jakarta area (Fig. 8). These varied characteristics, as well as the availability of building material, should be taken into consideration in the planning of the infrastructure development of the area.

Summary

The coastal plain of northern West Java was formed through the progradation of sediments carried by the rivers debouching into the Java Sea. The resulting patterns of sediment distribution are attributed to the interplay between the riverine and the marine systems. The whole process took place blanketing a Plio-Pleistocene unconformity surface, of which some of the structural elements continued to be active in Recent times. To understand the spatial relationships of the sediment assemblages in both horizontal and vertical senses, studies in Recent sedimentation have been carried out in the areas of the Cimanuk Delta and Jakarta Bay. The genetic history of the coastal plain has profound implications for the development of the area and the ,management of its resources.

The repercussions on groundwater resources and civil engineering aspects have been discussed to serve as examples.

References

Hehanussa, P. E.,1979. Penyusupan air laut ke dalam cekungan artois Jakarta (Saltwater encroachment in the Jakarta artesian basin). Paper presented at 5th Ann. Conv. Indon. Geol. Assoc.

________; S. Hadiwisastra; and St. Djoehanah 1976. Sedimentasi delta baru Cimanuk (Sedimentation in the new Cimanuk Delta). Geol. Indon. 311):21 - 35.

Hehuwat, F., 1972. The significance of zircon and rutile distribution pattern on the Sunda shelf. UN ESCAP Rept. 9th Session CCOP, pp.164 - 1 71.

________1977 Penyebaran biotop foraminifera Teluk Jakarta berdasarkan analisa "cluster" (The distribution of foraminiferal biotopes in the Bay of Jakarta based on cluster-analysis). Hiset Geol. Pertamb. 1 (1):1 - 3.

Sireger, M. S., and S. Hadiwisastra 1977. Penyelidikan sedimen Teluk Jakarta (Investigations on the sediments of the Bay of Jakarta). in Teluk Jakarta: sumber daya, sifat-sifat oseanologi serta permasalahannya. Lembaga Oseanologi National-LIPI Jakarta, pp.107 - 137.

Soekardi and M. Koesmono 1973. Pengamatan neotektonik den morfogenesa di daerah daratan Jakarta (Neotectonic and morphogenetic observations in the Jakarta area). Unp. Rept., Geol. Survey of Indonesie, no.1799.

Soekardi,R., and M. M. Purbo-Hadiwidjojo 1979. Cekungan artois Jakarta (The Jakarta artesian basin). Geol. Indon. 2 (1): 25-28.

Discussion

Muluk: Are you suggesting that the plan for Cengkareng Airport is wrong?

Hehuwat: No, but they have to consider the deeper geological structure of this area, in relation to other possible uses of the site.

Koesoebiono: What factors increase the salinity of tambaks?

Hehanussa: The problem of increased salinity in the tambaks may partly be due to the encroachment of saline water from below.

 

The oceanographic features of the coastal region between Jakarta and Cirebon

Oceanography
Geology
Biology

Introduction

The present paper presents a description of the oceanographical features of the coastal zone between Jakarta and Cirebon. From the outset it has to be stated that the paper is not intended to be an exhaustive source of information concerning the oceanography of this region. Rather it is a brief report of the facts and figures of the physical, chemical, biological, and geological parameters that describe its oceanographical features.

Research has been done on the coastal and land geology of the area, but not much has been done on its marine physics, chemistry, and biology. Therefore of necessity the present report contains mostly inferences and interpolations drawn from the oceanographical knowledge available on the adjacent areas, specifically the Java Sea and Jakarta Bay.

The paper consists of three sections: "Oceanography" prepared by A. G. Ilahude, "Biology" prepared by D. P. Praseno, and "Geology" prepared by Otto S. R. Ongkosongo. It is hoped that the paper may serve as the basis for discussion of the oceanography of the region.

Oceanography

A. G. Ilahude

The Monsoons

Situated between two continents and two oceans, and straddling the equator, the Indonesian archipelago is an ideal place for the development of the monsoon. The low atmospheric pressure of the equatorial trough crosses the equator twice a year in accordance with the shifting position of the sun in respect to the equator. During the northern summer a low atmospheric pressure area is formed over Asia as an extension of the equatorial trough while over Australia a high pressure area is formed as an extension of the subtropical high. Between the low and the high, the monsoon winds develop, in which the air flows from Australia to Asia. During the northern winter the reverse is the case (Wyrtki 1961).

During the northern summer the direction of the winds is east and southeast south of the equator, south on the equator, and southwest north of the equator. The wind speed is generally 25 to 40 knots. This period is called the southeast season, and the monsoon is called the southeast monsoon in Indonesia. During the northern winter the wind reverses its direction to become north and northeast north of the equator, north on the equator, and northwest south of the equator. The speed is 30 to 45 knots. The period and the monsoon are called the northwest season and the northwest monsoon, respectively. Between the two seasons, transition periods develop in which the direction of the wind is variable and the speed is weak. In the Java Sea, to which the coastal region between Jakarta and Cirebon belongs, the northwest monsoon is usually accompanied by heavy rainfall, and is therefore called the rainy season, while the southeast monsoon is called the dry season. The terms "east monsoon" and "west monsoon" are sometimes used in place of "southeast monsoon" and "northwest monsoon."

The monsoons are capable of creating and maintaining surface sea currents in the Indonesian archipelago. This is because of the following factors: (1 ) the wind is steady, and (2) the axis of the wind more or less coincides with the axis of the seas formed by the South China Sea, Karimata Strait, Java Sea, Flores Sea, and Banda Sea.

Thus in the Java Sea the surface currents flow to the east during the northwest monsoon and to the west during the southeast monsoon. The velocity of the current is 25 - 38 cm/see during the northwest monsoon and 12 - 25 cm/see during the southeast monsoon (Wyrtki 1961). During the transition periods the currents are variable and relatively weak.

In the coastal region between Jakarta and Cirebon the velocity of the currents generally varies from 5 - 40 cm/sec. Several observations in Jakarta Bay have indicated that the direction of the currents is basically in accordance with the directions of the monsoon. Apart from the monsoon, the current direction is also affected by the land and sea breezes, and its speed is influenced by the tides. The current direction tends to deviate away from the coast during the land breeze and toward the coast during the sea breeze. The current speed is usually stronger during the rise and ebb of tides, and weaker during the time of high and low water (Anonymous 1975). The coastal currents may also be affected by the coastline and the bottom topography, but so far no study in this area has been carried out.

Tides and Waves

Observation of tides in Jakarta Bay indicates that in this region they are diurnal, with one high water and one low water daily. The F (Form zahl) value is generally higher than 3; that is, around 4.9. The tidal range varies between 27 and 97 cm. The rate of occurrence of a tidal range greater than 50 cm is 86 per cent while that for a tidal range less than 50 cm is 14 per cent. The amplitude and phase of the major component of tides, standardized against the 0 hour (West Indonesia Time) are as follows (Anonymous 1975):

Component Amplitude (cm) Phase (degree)
M2 5.51 6.37
S2 2.68 -60.74
N2 1.18 32.90
K1 28.34 -21.75
O1 11.80 -86.98
M4 0.46 -41.06

The moon's influence on tides is observed mainly in tidal heights, the greatest range occurring during maximum lunar declination. Also in these regions the predominant diurnal tide may become mixed near minimum lunar declination (Anonymous 1972).

The tidal currents are generally weak, and merely strengthen or reduce the speed of non-tidal currents. Therefore they are only perceptible during the transition periods between monsoons, when the prevailing current systems are not fully developed (Anonymous 1972).

The velocity of tidal currents is believed to vary between 5 and 85 cm/see with the direction north and south in the Cirebon area, and west-northwest and east-southeast in the area between Tg. Krawang and Tg. Indramayu (Anonymous 1979).

Observation of waves in Jakarta Bay shows that wave characteristics (wave height H, wave period T, and wave wave-length L) in both northwest and southeast monsoons are determined by the wind velocity. These characteristics increase with increasing wind velocity. The values observed for the Jakarta Bay area are 1 - 10 dm for wave height, 1 - 8 sec for wave period, and 1 - 21 m for wave wave-length.

The direction of waves is dependent on the direction of the wind only for the offshore area. Close to the shore, the wave usually arrives perpendicular to the coastline due to refraction across the shallowing sea floor (Anonymous 1975).

Temperature

The water temperature in the coastal area between Jakarta and Cirebon is high, as it is in ail tropical regions. It ranges between 27.1 and 29.7C, with two maxima and two minima annually. The primary maximum with a temperature of 29.1 29.7C is generally found in April or May, the months of the first transition monsoon. The secondary maximum with a temperature of 28.6 - 29.2 C occurs in October or November, the period of the second transition monsoon.

The primary minimum temperature of 27.4 - 28.2 C is usually found in December or January, during the northwest monsoon, while the secondary minimum of 27.5 28.3 C occurs in August, during the southeast monsoon.

In exceptional cases the temperature may reach a highest value of 30.5C or a lowest value of 26.5C.

The water temperature is about equal to the air temperature at sea level, which also has two maxima and two minima annually. The winds that flow during the monsoons influence the water temperature greatly. Similarly, rainfall during the northwest monsoon and evaporation during the southeast monsoon also reduce the temperature of the water. This is true not only of the coastal region between Jakarta and Cirebon, but also of the whole Java Sea (Whyrtki 1957).

In the Jakarta Bay area, Arief (unpublished) found a similar annual course of surface water and air temperatures. In addition he also found the temperature in Jakarta Bay, which can be considered to be representative of the whole coastal zone between Jakarta and Cirebon, to be 0.8 C higher than in the open Java Sea. Thi's is believed to be due to the landmass effect of Java.

Muluk et al. (1976) reported that the water temperature in the main river of Citarum is 26.0 - 28.0C during the rainy season of the northwest monsoon and 27.0 - 30.0C during the dry season of the southeast monsoon. In the tributary rivers of the Citarum, the temperature is 26.0- 27.0 C and 29.0 - 30.0C, respectively.

Salinity

The salinity in the coastal area between Jakarta and Cirebon generally varies between 31.0‰ and 33.0‰.

Due to the influence of the high salinity of the Pacific waters that come to the region through the South China Sea in the northeast monsoon and through the Flores Sea in the southeast monsoon, two maxima and two minima of salinity are usually observed in this region annually. This information is inferred from the papers of Soeriaatmadja (1956) and llabude et al. (1975). The primary maximum, with salinity value of 32.5 - 33.0 %o, is usually found in November, due to the mixing of the coastal water with Flores Sea water of around 34.2%o, brought to the region by the southeast monsoon current. This maximum is also strengthened by the dryness of the monsoon in this period. The secondary maximum usually occurs in May, with salinity 31.7 - 32.0 %o and is due to the mixing of the coastal water with the South China Sea water of around 32.5‰ salinity.

The primary minimum, usually found in February with salinity value of 30.6 - 31.0%o, is caused by the heavy rains that occur during the northeast monsoon. The secondary minimum with value of 31.0 - 31.4%o is usually found in July and is due to the influence of the low-salinity water mass of 31.0 - 31.8%o formed by the mixing of sea water with the river water from South Kalimantan. The formation of this low salinity is discussed by Sjarif (1959).

Apart from the seasonal factor, the salinity in the coastal region between Jakarta and Cirebon is also influenced by the river drainage, especially in Jakarta Bay. In front of the river mouths within this bay, the surface salinity can be as low as 15 %o ( llahude and Soepangat 1977).

In the various depositional environments in the Cimanuk Delta, Hehanussa etal. found that salinity varies between 22.1 and 38.9 ‰. Most of the values lie between 30.0 and 33.7 ‰.

In the rivers themselves the salinity is usually low. Muluk et al. (1976) found the salinity in the main flow of the Citarum River to be 0 to 0.5‰ during the rainy season and 0 to 31.0 ‰ during the dry season. A. J. van Bennekom and R. de Vries "Personal communication) found salinity values of 3.4 %o for the Ciujung River and 1.8 %o for the Cilontar River.

Seston

Measurements on seston (suspended particulate matter) have also been carried out in the coastal area and in the rivers of West Java. Nontji and Soepangat (1977) found the value of seston in Jakarta Bay to be 13.1 - 186.49 mg/l near the river mouths and 5.0 - 19.4 mg/l in the offshore areas. They found that the value of seston has a high negative correlation with the salinity of the water. The seasonal variation of rainfall on land may also cause variation of the seston concentration in Jakarta Bay.

In the river water, Muluk et al. (1976) reported the values of 95 342 mg/l during the rainy season and 27 - 30 mg/l during the dry season in the Citarum River. A. J. van Bennekom and R. de Vries (personal communication) reported the value of 270 mg/l and 350 mg/l, respectively, for the Ciujung and Cilontar rivers, West Java, during the rainy season (December 1978).

Dissolved Oxygen and pH

Edi Legowo (unpublished) has reported the result of LONLlPl's observation on dissolved oxygen in Jakarta Bay. He found that the oxygen concentration during the northwest monsoon varied between 4.08 and 4.83 ml/l and in the southeast monsoon varied between 3.14 and 5.35 ml/l, the average values being 4.46 and 4.45 ml/l, respectively.

The dissolved oxygen varied between 4.46 and 5.21 ml/l in the northwest monsoon and 4.42 and 4.58 ml/l in the southeast monsoon, with the average values of 4.62 and 4.51 ml/l, respectively. The percentage of oxygen saturation was 96.3 per cent for the northwest monsoon and 98.7 per cent for the southeast monsoon. Supersaturation values from 110 - 120 per cent were usually found during the southeast monsoon.

Muluk et al. (1976) found dissolved oxygen in the Citarum River to vary between 1.4 and 4.8 ml/l with percentage saturation of 19.1 to 61.9 per cent.

The pH in Jakarta Bay was found by Santoso et al. (1977) to be 7.5 - 8.2 near river mouths, and 7.9 - 8.2 in the offshore area, which is considered normal. In the Citarum River the pH value ranges between 6.2 and 7.7 (Muluk et al. 1976).

Trace Elements

Studies of water quality have also been carried out in the coastal region of West Java (Table 1). The results indicate that for certain elements, such as lead, copper, and mercury, the sea water has a larger concentration than the river water.

Santoso et al.., using the criteria of the U.S. Federal Water Pollution Control Administration of 1968, decided that this concentration is larger than the standard set by the Administration. They believe that the high concentration of trace elements in Jakarta Bay is due to the outflow of industrial wastes and that such high concentration can have a deleterious effect on the marine organisms in the region.

Table 1. Values of Trace Elements in the Coastal Region between Jakarta and Cirebon

Elements

Author and Locality

Santosa et al. 1977

Muluk et al. 1976 LON-LIPI*

Jakarta Bay

Citarum River Jakarta Bay
River mouths Offshore
Pb mg/l 0.14 - 0.32 0.14 - 0.26 tr-0.03 -
Cu mg/l 0.02 - 0.10 0.02 - 0.08 tr-0.04 0.36 - 3.00
Fe mg/l - - 0.29 - 1.50  
Zn mg/l - - tr-0.25 0.24 - 0.65
Cd ug/l tr** - 4.00 - tr-6.00 -
Hg ug/l 0.15 - 0.75 0.25 - 4.25 tr -1.00 -
Co ug/l     5.40 - 17.10 -

* LON-LIPI = National Institute of Oceanology, LIPI (unpublished data)
**tr= trace

Table 2. Values of Nutrients in the Coastal Region of West Java

Nutrients

Author and Locality

Santoso et al. 1977 Muluk et al. 1976 van Bennekom & de Vries (personal communication) LON-LIPI
Jakarta Bay, mg/l Citarum River mg/l Ciujung and Cisadane rivers, mg/l Jakarta Bay mg/l
River mouths Offshore
Phosphate 0 - 0.42 0 - 0.49 0.02 - 0.21 0.01 - 0.12 0 - 0.02
Nitrate 0-0.22 0 - 3.10 tr-0.08 0.10 - 0.23 0 - 0.03
Ammonia 0-tr 0-tr tr-0.09 0.02 - 0.06 -
Silicate - - 0.40 - 46.25 15.8 - 21.00 0 - 0.42

 

The Nutrients

The concentration of nutrients of the sea water, consisting of phosphate-phosphorus, nitrate-nitrogen, and silicate-silicon, has been studied by LON-LIPI in various Indonesian waters, including the Jakarta Bay area. The results of this study show that the nutrient values generally vary from 0-0.02 mg/l for phosphate, 0 - 0.03 mg/l for nitrate, and 0 - 0.42 mg/l for silicate (Table 2). The concentration of nutrients is very much affected by the fresh-water drainage from the land, and therefore it varies seasonally, the high concentration usually being found during the rainy season of the northwest monsoon.

Measurements of nutrients in the river water indicate that the rivers have higher concentrations of nutrients than the sea. For example Santoso et al. (1977) reported values of 0 - 0.42 mg/l and 0 - 0.22 mg/l for phosphate and nitrate, respectively, for the river mouths in Jakarta Bay. Muluk et al. (1976) found the concentration of 0.02 - 0.21 mg/l, trace-0.08 mg/l, and 0.40 - 46.25 mg/l for phosphate, nitrate, and silicate, respectively in the Citarum River, while van Bennekom and de Vries (personal communication) found the values to be 0.01 0.12 mg/l, 0.10 - 0.23 mg/l, and 15.8 - 21.00 mg/l for phosphate, nitrate, and silicate, respectively, in the Ciujung and Cisadane rivers (Table 2).

 

References

Anonymous 1972. Kepanduan bahari untuk Djawa, Direktorat Hidrografi Angkatan Laut Rl. Djakarta. 537 p.

_________1975. Laporan hasil penelitian terhadap arus, gelombang, sedimentasi den pasang surut di perairan pantai Marunda. Lembaga Oseanologi Nasional, 63 P.

_________1979. Daftar arus pasang surut. Jawatan Hidro-Oseanografi Angkatan Laut Rl,Jakarta: 1 - 130.

Arief, D., Keadaan suhu permukaan air laut den suhu udara di perairan Teluk Jakarta. Teluk Jakarta: pengajian fisika, kimia, biologi den geologi, 1975 - 1979. (In preparation for publication.|

Ilahude, A. G.; D. P. Praseno; O. H. Arinardi; den A. Nontji 1975. Peta oseanografi hasil pelayaran selama Pelita I 11969 - 1974). In A. Soegiarto den S. Birowo (eds.), Atlas oseanologi perairan Indonesia den sekitarnya. Lembaga Oseanologi Nasional-LIPI Jakarta Buku No. 2:1 - 32,483 charts.

Ilahude, A. G., and 1. Soepangat 1977. Pengamatan hidrologi di Teluk Jakarta, Januari 1977. Monitoring Teluk Jakarta, Laporan Pelayaran No. 6 Lembaga Oseanologi Nasional-LIPI, Jakarta 9 - 41.

Ilahude, A.G.; I Soepangat; den P. Sianipar 1978. Pengamatan hidrologi Teluk Jakarta, Januari 1978. Monitoring Teluk Jakarta, Laporan Pelayaran No. 10. Lembaga Oseanologi Nasional-LIPI Jakarta: 6 - 43.

Legowo, Edi, Oksigen di permakaan perairan Teluk Jakarta. Teluk Jakarta: pengajian fisika, kimia, biologi den geologi, 1975- 1 979. (In preparation for publication.)

Muluk, C.; Koesoebiono; S. T. H. Wardojo; D. R. O. Monintja; M. I. Effendie; and S. Sosromarsono 1976. Study penentuan kriteria kualitas lingkungan perairan den biotis. Proyek Pend. Penel. Lingkungan IPB: 1 - 174.

Nontji, A., and 1. Sopangat 1977. Seston di Teluk Jakarta. In Teluk Jakarta: sumber daya, sifat-sifat oseanologis serta permasalahannya. Lembaga Oseanologi Nasional-LIPI, Jakarta, pp. 219 - 231.

Santoso; W. Aboejoewono; J. Bilal; and I. Bachtiar 1977. Inventarisasi kualitas air permukaan daerah Teluk Jakarta timur. In Teluk Jakarta: sumber daya, sifat-sifat oseanologis serta permasalahannya. Lembaga Oseanologi Nasional-LIPI, Jakarta, pp.197 - 217.

Sjarif, S., 1959. Seasonal fluctuations in the surface salinity along the coast of the southern part of Kalimantan. Mar Res. Indonesia 4:1 25.

Soerisatmadja, R. E., 1956. Seasonal fluctuations in the surface salinity off the north coast of Java. Mar. Res. Indonesia 1 :1 - 19.

Wyrtki, K., 1957. Precipitation, evaporation and energy exchange at the surface of the Southeast Asian Waters. Mar. Res. Indonesia 3:7 - 26.

_________1961. Physical oceanography of the Southeast Asian Waters. Scripps Institution of Oceanography, Naga Report 2:1 - 95.


Contents - Previous - Next