Contents - Previous - Next


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


6. Appendices

Appendix 1: List of participants
Appendix 2: Excursion guide to the cimanuk delta complex, west Java
Appendix 3: Review of the field trip to the Cimanuk Delta

Appendix 1: List of participants

Prof. Dr. E. C. F. Bird
Department of Geography
University of Melbourne
Parkville, Victoria 3052
Australia

Mr. Sujatno Birowo
Assistant Director for Development
National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P.O. Box 580 Dak
Indonesia

Dr. A. C. J. Burgers
Senior Programme Officer
Programme on the Use and Management of Natural
Resources
The United Nations University
29th Floor, Toho Seimei Building
15-1, Shibuya 2-chome, Shibuya-ku
Tokyo 1 50
Japan

Dr. William Collier
Agricultural Development Council
c/o Department of Social Economy
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Prof. Kardono Darmojuwono
Deputy Chairman III
National Mapping Agency (BAKOSURTANAL)
Jalan Raya Jakarta-Bogor Km. 46
Cibinong
Indonesia

Mr. Lukman Effendi
National Institute of Oceanology
Indonesian Institute of Sciences
Jalan Pasir Putih 1, Ancol Timur
Jakarta Utara

Mr. Peter Edward Hehanussa
National Institute of Geology and Mining
Indonesian Institute of Sciences
Jalan Cisitu, Sangkuriang
Bandung
Indonesia

Dr. Fred Hehuwat
Director of the National Institute of Geology and Mining
Indonesian Institute of Sciences
Jalan Cisitu, Sangkuriang
Bandung
Indonesia

Mr. Johannes Hutabarat
Faculty of Animal Husbandry and Fisheries
Diponegoro University
Jalan Imam Barjo SH No. 1
Semarang
Indonesia

Mr. Abdul Gani llahude
Assistant Director for Research
National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P.O. Box 580 Dak
Indonesia

Dr. Shigero Iwakiri
Faculty of Fisheries
Kagoshima University
4-50-20 Shimoarata
Kagoshima 890
Japan

Mr. Koesoebiono
Programme Manager
Coastal Zone Management (CZM)
Centre for Natural Resource Management and Environmental Studies (CNRMES)
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

A. S. Kumanireng, Dr. Sc.
Head of Marine Sciences
University of Hasanuddin
Ujung Pandang
Indonesia

Miss Anna Manuputty
National Institute of Oceanology
Indonesian institute of Sciences
Ambon Station
Poka
Ambon
Indonesia

Mr. G. Missen
Department of Geography
University of Melbourne
Parkville, Victoria 3052
Australia

Mr. Chairul Muluk
Graduate Research Assistant
CZM, CNRMES
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Mr. Ngadiono
Graduate Research Assistant
CZM, CNRMES
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Mr. Otto S. R. Ongkosongo
National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P.O. Box 580 Dak
Indonesia

Prof. Dr. Soeratno Partoatmodjo
Director, Centre for Natural Resource
Management and Environmental Studies
(CNRMES)
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Dr. Nicholas Polunin
World Wildlife Fund
P.O. Box 133
Bogor
Indonesia

Mr. Djoko Prawoto Praseno
Head of Scientific Service Centre
National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P. O. Box 580 Dak
Indonesia

Mr. Suhardjono Prawiroatmodjo
National Biological Institute
Indonesian Institute of Sciences
Jalan Ir. H. Juanda
Bogor
Indonesia

Mr. Jacob Punyanan
Naval Hydro-oceanographic Office
Jl. Gunung Sahari 87
Jakarta
Indonesia

Mr. Neville Rosengren
Department of Geography
University of Melbourne
Parville, Victoria 3052
Australia

Mr. Ruspandi
Space and Aeronautic Agency
Jl. Pemuda Persil No. 1
Jakarta
Indonesia

Mr. Tjahjono Samingan
Department of Botany
Faculty of Agriculture
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Prof. Dr. Didin S. Sastrapradja
Deputy Chairman for Natural Sciences
Indonesian Institute of Sciences
Jalan Teuku Cik Ditiro 43
Jakarta
Indonesia

Dr. Rudolf Sinaga
Department of Social Economy
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Mr. Siregar, M.Sc.
Director, Institute of Ecology
University of Padjadjaran
Jalan Banda 40
Bandung
Indonesia

Dr. Aprilani Soegiarto
Director of the National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P.O. Box 580 Dak
Indonesia

Mr. Tatang Sujastani
Marine Fisheries Research Institute
Jalan Kerapu 12
Jakarta
Indonesia

Mr. Sukristijono Sukardjo
National Biological Institute
Indonesian Institute of Sciences
Jalan Ir. H. Juanda No. 22
Bogor
Indonesia

Mr. Made Sumatra
Atomic Energy Agency
Pasar Jum'at, Kebayoran Lama
Jakarta
Indonesia

Miss Tuti Susilowati
Marine Fisheries Research Institute
Jalan Krapu 12, Sunda Kelapa
Jakarta
Indonesia

Dr. R. T. M. Sutamihardja
Water Quality Manager, CNRMES
Bogor Agricultural University
Jalan Raya Pajajaran
Bogor
Indonesia

Mrs. Suminarti H. Thayib
National Institute of Oceanology
Indonesian Institute of Sciences
Kompleks Bina Samudra
Jalan Pasir Putih No. 1
Ancol Timur, Jakarta Utara
P.O. Box 580 Dak
Indonesia

Dr. Andrew P. Vayda
Department of Human Ecology & Social Sciences
Rutgers University
New Brunswick, N.J. 08903
USA

Mr. P. J. Wisnusudibyo
National Mapping Agency (BAKOSURTANAL)
Jalan Raya Jakarta-Bogor Km. 46
Cibinong
Indonesia

 

Appendix 2: Excursion guide to the cimanuk delta complex, west Java

P. E. Hehanussa

Introduction

The northern coastal plain of West Java is formed of an alluvial lowland up to 40 km wide and extending from Serang in the west to Cirebon in the east. It consists largely of river deposits and lahars from the volcanoes in the hinterland. Four large delta complexes crown this coastal plain; from west to east these are the Cisadane, Citarum, Cipunegara, and Cimanuk deltas. Eustatic sea level changes and tectonic movements during the Quaternary influenced the development of the geometry and structure of these deposits.

This coastal plain overlies the southern part of the northwest Java oil basin. Onshore, this oil basin consists of several subbasins, i.e., the Ciputat sub-basin approximately south of Jakarta, the Pasir Putih sub-basin south of Karawang, and the Jatibarang sub-basin in the vicinity of Jatibarang. Crude oil and gas have recently been produced from the Jatibarang sub-basin. A collector and marine loading station was completed in 1976, located in Balongan, 10 km southeast of the Cimanuk Delta. Natural gas from an offshore field north of Pamanukan is piped in and utilized by the urea (fertilizer) factory near Cikampek, a cement factory in Cibinong, the city of Jakarta, and the Krakatau steel plant in Cilegon.

Most of the coastal plain is flat with slopes of less than 5 The greatest part is occupied by rice fields with a water supply from the Jatiluhur dam. Some marshes and coastal wetlands are situated near the shoreline. A zone of brackish water and shallow groundwater potentials is situated behind it as shown in Figure 1. Beach ridges developed around the large deltas, nearly all of them being now occupied by roads, villages, or hardwood plantations. An overall view of the area is given in the two LANDSAT photographs (Plates 1 and 2).

Artesian water was produced from the Quaternary sediments which in most cases are the uppermost 300 m of the sedimentary column. The Cilegon artesian basin has a potential of 6.2 million m/year, the Serang-Tangerang basin 15.7 million m/year, the Jakarta basin 42.1 million m/year, and the Karawang-Jatibarang artesian basin 39.3 million m/year. The intake areas of these artesian basins are located on the southern borders of the coastal plain, at the foot of the volcanic belt. Salt-water encroachment is mostly encountered in aquifers with an under-balanced potential-over-production ratio. Water from deeper aquifers is usually mineralized, containing more than 1,300 ppm soluble salts. Annual rainfall in the northern coastal plain of West Java varies between 1,000 and 2,500 mm (Fig. 2).

FIG. 1. Groundwater and main water divide of Java

FIG. 2. Mean annual rainfall in West Java

Table 1. Lengths and Catchment Areas of Rivers in the Northern Part of West Java

Name of River Length
(km)
Catchment area (km)
Cisadane 112 1,479.1
Ciliwung 82 611.4
K. Bekasi 45 1,451.9
Citarum 250 5,969.0
K. Pegadungan 58 628.8
Cilamaya 65 322.4
Ciasem 68 690.9
Cipunegara 98 1,492.9
Cimanuk 182 9,650.2
Ciwaringin 53 485.4

The Cimanuk Delta Complex

The Cimanuk is the second longest river in West Java after the Citarum, but it has the greatest catchment area (Table 1), 9,650 km; the head of the river is located 180 km upstream, south of Garut. It flows through Quaternary volcanics, Miocene and Quaternary sediments, and the alluvial plain of north West Java (Fig. 3).

Molengraaf postulated in 1919 that during the Pleistocene ice age, the Sunda shelf was dry and the Cimanuk was a tributary of a big Sunda river. This big river flowed to the east towards the Makassar strait. The conspicuous Cape Ujung, between Indramayu and Cirebon, according to PurboHadiwidjojo (1964) is a remnant of an ancient delta which developed after the rise in sea level which drowned the big Sunda river. Tjia (1965) and the author have reconstructed the development of shorelines as shown in Figure 4. These paleo-shorelines are derived from studies on topographic maps, aerial photographs, and field investigations. A marked change in the river course is observed near Kertasmaya. Westward deflection is also observed in other large rivers in north West Java as the result of waves generated by the dominant east wind around the year.

FIG. 3. Geologic map of the Cimanuk River Basin

FIG. 4. Coastal changes on the Cimanuk Delta

FIG. 5. Development of the Cimanuk Delta

FIG. 6. Coastal accretion on the Cimanuk Delta

The dynamics of the shoreline in the last century around the Cimanuk River mouth are shown in Figure 5. Shorelines in 1857 and 1917 were documented from old topographic maps. The Cimanuk had three major distributaries which diverged in the vicinity of Sindang. Comparing maps of 1946 and 1974, one can demonstrate a shifting of the river channel course from northwest to northeast. This change in direction was the result of erosion of the river bank near the village of Pabean Udik. After this crevasse formed, most of the water flowed through the river channel from Sindang to Indramayu and very little through the Kali Anyar. Coarse grain sedimentation is very active in the Kali Anyar, while sedimentation in the Cimanuk is otherwise mostly around the river mouth.

Monitoring the accretion of the new Cimanuk Delta resulted in the map shown in Figure 6. At first the Cimanuk developed only one channel, Pancer Song, but sedimentation was very active, and this river became too shallow. Outflowing water then cut a new channel, flowing to the north, and produced other distributaries, Pancer Payang and Pancer Balok. Several triangulation points were constructed along the river mouth by LGPN-LIPI as a reference for their field measurements.

The height of points in these triangulations is based on a system called IVP or "Indramayu vloed peil." There now exist several systems for height measurement: IVP, NWP or "Nauwkeurigheids water passing peil," and MSL or mean sea level. The relation between these systems is that IVP is 0.262 m above MSL and 1.138 m below NWP, or NWP is 1.4 m above MSL (Table 2).

Sea-level calculations by NEDECO, based on short-period observations in Tegal and Rentang, together with Tide Tables for Indonesia, resulted in these figures:

HHSL = IVP + 0.45 m
HSL = IVP - 0.06 m
MSL = IVP - 0.26 m
LSL = IVP - 0.49 m
LLSL = iVP - 0.85 m

Floods are frequent in the coastal plain around the Cimanuk. This is not surprising for the river is shallowing downstream and its bed is approaching the surrounding topography. In many cases the floods are caused by undermining of the dykes bordering the river. In most cases the undermining of these dykes coincides with intersections of the river channel and the paleo-shorelines as shown in Figure 5. Differences in the water yield from the Cimanuk in the dry and rainy seasons are enormous. Monthly maximum and minimum measurements from 1970 to 1974 are presented in Table 3.

Salt-water encroachment has affected a wide area around me Cimanuk River. In the dry season, sea water was detected in the Cimanuk River, near Bangkir at a distance of 7 km from the coast. Groundwater has been affected further inland. At Jatibarang the quality of the groundwater fluctuates with the season. In the rainy season the chloride content is below 250 ppm while in the dry season it exceeds 1,000 ppm. In beach ridges and paleo-river-channels the chloride content does not change much during the year. The greatest seasonal changes are observed in the alluvial plain, which seems to have been strongly affected by the wandering of the river mouth. Field measurements made in 1976 are presented in Table 4.

In general we can explain the coastal forms as the result of the interaction between rates of sedimentation (Rs) and rates of erosion (Re). The form of the Cimanuk Delta demonstrates that in the last decade Rs has been greater than Re, as shown in Figure 7. The three excursion sites, Tiris, Song, and Balongan, represent three different coast dynamics. Tiris is a place where Rs is in balance with Re, while at Song we see that Rs is much greater than Re. In Balongan we see an erosional feature, with Rs smaller than Re.

Table 2. Relative Depths of Several Base Levels in the Cimanuk Area

Table 3. Discharge of the Cimanuk River Measured near Rentang, in m per Second

  1970
min/max
1971
min/max
1972
min/max
1973
min/max
1974
min/max
January 801300 1001425 1401570 601580 551680
February 651315 75/380 90/290 651540 851685
March 1051560 551420 1451570 901585 901480
April 551520 751255 751255 801600 851790
May 551300 1001330 50/385 100/890 50/550
June 30/465 351315 20125 551490 20/100
July 10/200 15/130 15/20 35/330 151175
August 5155 15135 15120 201100 251520
September 5155 5/30 - 130 251490 251230
October 251150 5/190 5/5 351175 501685
November 101315 50/220 101100 701515 651400
December 1701390 1401540 251440 851450 1301950

Table 4. Salinity Measurements in the Cimanuk Delta Complex (1976)

Location Nature of deposit Cl in ppm.    
Balongan back swamp 3,801    
Penganjang alluvial 2,605 1,132 518
Sindang paleo-channel 97 111  
  alluvial 1,030 862  
Lohbenar alluvial 1,072    
Jatibarang alluvial 258 174  
Mundu alluvial 967 808  
Karangampel beach ridge 307    
Pabean Udik alluvial 518    
Indramayu alluvial 1,030    

Sedimentary environments in an active delta are marked by thick sand deposits and a rapid alternation among clays, silt, and fine sand. The geometry of the sand bodies in many cases is lenslike, depending on the environment of deposition. Five marine depositional environments are shown in Figure 8, three of which have a grain size of sand. It is of economic importance to differentiate among these three kinds of sand, which in many cases is difficult. The three sand bodies are barrier sands of the interdistributary area, barrier sands of the interdeltaic zone, and river mouth bar sands. Silt is deposited further seaward and pro-delta clays are usually the outermost part of the marine deltaic sedimentation. Fluviatile sediments are concentrated in and near the river channel. They usually alternate with carbonaceous material from plants growing on the substratum.

FIG. 7. Bathymetric map of the Cimanuk Delta (1974) and excursion sites

FIG. 8. Depositional environments in the Cimanuk Delta

Excursion Sites

Three excursion sites have been chosen to represent the Cimanuk Delta, each with different physical and chemical environments. Tiris is a small village on the ancient Cimanuk Delta, Song is a distributary on the active Cimanuk, and Balongan is a place where beach ridges characterize the coastal zone.

The coastal plain surrounding the Cimanuk shows gradual changes from the sea toward the land. Near the coast it is characterized by swamp vegetation consisting mostly of mangroves. The species change landward, becoming taller and having bigger trunks. In most cases this mangrove zone is the area affected by tidal fluctuations. Farther inland we see the fish ponds or tambak, which seem to be a buffer zone. Swamps with nipah trees usually border the tambak. And then we can see rice fields which have a typical drainage pattern as shown in Plates 3,4, and 5. Villages and hardwood plantations are usually associated with the river bank or paleochannel and beach ridges. These places are chosen because they are relatively free from floods, because of their height, and because of their potential as fresh-water reservoirs.

The growth of the Cimanuk Delta complex as shown in Figure 5 with coastal succession from line 1 to 5 leaves its signature in the rural development. A rather high complex consisting of conglomerates near Jatitujuh was developed into sugar cane plantations. Paleo-channels and beach ridges became village sites, and in many places roads are built on this natural higher land. In many cases, floods are the result of undermining the dykes that were built alongside the Cimanuk River. Surprisingly the points of dyke failure are often at intersections between ancient shorelines and the present river.

A complex of salt-drying ponds can be observed near Losarang. This particular place seems to have been a stable coastline in terms of the historical interpretation made from aerial photos. Production is limited to the dry season because several rivers notorious for their floods border this area.

Tiris (Fig. 9) is a small village located in the interdistributary area, west of the new Cimanuk Delta. In the sedimentary environment, it was classified as a barrier sand of the interdistributary area. Two reference points have been set up by LGPN-LIPI in the area. TP2 is +0.58 IVP and TP3 is +0.28 IVP. There is a diminishing mangrove area due to the larger tambak development, especially southeast of Tiris. North of TP2, a new land area has developed in the last two years. In Tiris we can observe different mangrove species developing landward. New tambak have been constructed which we will visit. A zone of swamps and sawah is located in the hinterland. A paleo-channel to be passed during the trip to Tiris is characterized by a hardwood plantation. A rain-water collector is located at the edge of this paleo-channel.

Song is the oldest distributary of the new Cimanuk Delta which developed in 1947. In the dry season the water is too shallow for transportation. Two reference points, i.e., TP7, +0.48 IVP, and TP8, +0.31 IVP, are located near the river mouth. This accreting shoreline is indicated by sand which was concentrated by the last wind. In the southern part tambak have been developed, with mangrove plantations facing the sea. Rice fields observed along the river channel depend heavily on the discharge of the river, for salt-water encroachment starts as soon as the discharge diminishes.

Balongan is located southeast of the new Cimanuk Delta. It consists of several beach ridges and back swamps (Plate 6). An oil collecting and marine loading station is located nearby. The shoreline shows erosional features which can be observed in the field. Mangroves along the shore have been destroyed and the tambak are facing erosion by the sea. Nipah grows in swamps bordering the tambak, and the beach ridges are characterized by coconut trees. In this area geo-electric and seismic measurements will be demonstrated in the field.

Conclusion

The Cimanuk Delta complex in West Java is an excellent model to study coastal processes. Coastal dynamics, and vegetation evolution can be observed and monitored. Changes due to manmade structures have also affected parts of this delta complex.

The three excursion sites represent three different sedimentation environments, with differences in soil development, differences in faunal and floral associations, and differences in coastal processes, stable, depositional, and erosional.

References

Allen, J. R. L., 1965. Late Quaternary Niger delta and adjacent areas: Sedimentary environment and Lotho facies. Bull. AAPG Vol. 49, pp. 547 - 800.

Hadiwisastra, S., 1978. Kumpulan Ostrakoda Resen dari Delta Cimanuk. Riset Geologi den Pertambangan j. 1, no. 2, p. 9820.

Hehanussa, P. E., 1978. Potensi den kualitas air tanah di daerah Lemahduhur, Jawa Barat. LGRN-LIPI Bandung.

___________1979, The Cimanuk Delta Complex, West Java, Indonesia. Workshop on Coastal Geomorphology, Singapore and Malaysia.

___________; F. H. A. Hehuwat; Hadiwisastra; St. Djuhanah; and

Suwijanto 1975. The formation of the northern coastal plane of West Java and its effect to the production of ground water. Seminar Air Tanah Untuk Irigasi, Surabaya.

___________S. Hadiwisastra; and St. Djuhanah 1975. Sedimentasi Delta Baru Cimanuk. Geologi Indonesia j. 3, no.1, pp 21 - 35,

Hehuwat, F. H. A., 1972. The significance of zircon and rutile distribution patterns in the Sunda Shelf. CCOP Ninth Session, 1972.

Katili, J. A,, and H. D. Tjia 1969. Outline of Quaternary tectonics of Indonesia. Bull. Nat Inst. Geol. and Min, vol. 2, no. 1, pp 1 - 10.

Patty, E. J., 1978. Penyelidikan air tanah den permasalahannya. Direktorat Geologi, Bandung.

Purbo-Hadiwidjojo M. M.,1964. On the Cimanuk River Delta, West

Java. Bull. Geol Survey of Indonesia, vol.1, no. 2, pp. 35 - 38.

Smit Sibinga 1948. Pleistocene eustacy and glacial chronology in Java and Sumatra. Nerh. Ned. Geol. Mijnb. Gen. Geol. Serie 15, pp.1 -31.

Tjia, H. D.,1964. On the Cimanuk River Delta. Bull. Geol. Survey of Indonesia, Vol. 1, no. 1, pp. 17 - 19,

___________1965. Course changes in the lower Cimanuk River, West Java. Inst. Tech. Bandung, Contr. Dept.. Geol., no. 62, pp. 77 - 82.

___________; Sukendar Asikin; and R. Soeriaatmadja 1968; Coastal accretion in western Indonesia. Bull. Nat. Inst. Geol. and Min., pp. 15-46.

FIG. 9. Tiris, Excursion site I

FIG. 10. Pancer Song, Excursion site 11

FIG. 11. Balongan, Excursion site III

 

Appendix 3: Review of the field trip to the Cimanuk Delta

Eric C. F. Bird

Introducing the review, the project co-ordinator (Eric Bird) congratulated the organizers of the field trip, Peter E. Hehanussa and Otto S. R. Ongkosongo, on their achievement in arranging so complicated an excursion over so short a period. It had been extremely useful to have on-site discussions, and the participants had now gained a clear impression of the Cimanuk Delta and its physical and human environments.

However, during such a trip it is inevitable that people form into small groups to discuss features and problems as they are encountered en route, and it is difficult for everyone to know all that has been seen and said. At one point (Tiris) there were no less than six small groups simultaneously holding animated discussions: one on the muddy shore, another in the mangroves, a third on the sandy ridge, a fourth at the inlet to the tambak, a fifth in the midst of the tambak, and a sixth at the edge of the rice fields. Usually an evening session enables participants to distill all the information and discussion, but we had no time for such a session in Indramayu, and so we must review it all now.

In addition we must try to resolve three questions:

  1. What techniques are to be included in the training course?
  2. What research can be done during the next field trip to the Cimanuk Delta?
  3. What are the important gaps in our knowledge of the Cimanuk Delta?

Hehanussa commented on the difficulty of discovering who the decision makers were on the Cimanuk Delta, and how they can be involved in field studies and acquainted with the results of the research. He also remarked that the field trip had been in fine dry weather, and that there was an accessibility problem in the wet season. Some attention should be given to the plants of economic value that could be introduced, for example at the mouth of Pancer Song.

Sukristijono mentioned some problems of plant ecology, notably the importance of areas of seed dispersal in determining the available species. At the mouth of the Song distributary the pioneer vegetation was Cyperus marsh, not mangroves, although these formed the seaward zone on the delta flanks. Grasses may grow better on sandier sediment, mangroves on muddier sediment. Some interesting transplanting experiments could be run here.

The river levees appeared to have a higher sand content than the shores south of the river mouth, and offshore, waves were re-working the sand-silt-clay mixture and sorting a sand bar that could be moving onshore.

Muluk remarked that the boundary between tambak and rice fields was a salt-intrusion zone, and suggested it should be a buffer zone of some other land use.

It was noted that the tambak develop hypersalinity unless a constant flow of sea water can be maintained through them. In the dry season many of them are empty and desiccated, and there is a risk of upward movement of salt from the subsoil in addition to that derived from sea-water evaporation. One answer might be to pump river and sea water up into reservoirs from which a managed flow could maintain water of correct salinity in the tambak, enabling them to be productive most, or all, of the year. Windmills could be used to provide power for pumping.

There was much interest in the construction of tambak on the mudflats along the shores of growing deltas even before the vegetation colonized. Investigation of ownership of this new land was necessary: Who allocated the areas for tambak construction? Hazards of tambak development here include a high erosion risk, especially if the river mouth migrates.

Missen was interested in the evidence that outside owners were recruiting outside labour to dig the tambak-an amazing "labour shortage" situation in such a densely populated region. There was discussion on who designs the tambaks, and especially the pattern of inlet and outlet channels, the size and location of which are critical in determining the water supply to the tambak and their salinity regime. It was noted that tambak have been in use on the north coast of East Java for several centuries, but there is a need for historical studies of this traditional brackish-water fish culture, of the innovations that have modified it over time.

More broadly, there is a need for socio-economic studies of each of the land-use elements in the Cimanuk Delta coastal region, not only tambak, mangrove use, and rice fields, but also dry-land farming, kitchen gardens, and brick making.

In general discussion it was acknowledged that during a project of just under one year it would be possible to study only short-term dynamics, but that conditions in the dry season and at the beginning and end of the wet season could be sampled. it will be necessary to consider in review how typical the Year 1979 - 80 has been, and what ongoing studies are necessary to build up a knowledge of longerterm trends. The session closed with practical discussions on how tides could be monitored in the delta region, what patterns of sediment, water, and vegetation sampling were necessary, and what kinds of detailed field mapping were required. The project co-ordinator then handed over to Mr. Rosengren the task of initiating the training course that followed the programmatic workshop.


Contents - Previous - Next