Hydrodynamic Modelling using Software of Mike21 in the Land

Reclamation of Jakarta Bay: Current Condition and Master Plan

Rahmad Agung Saputra

, Rizqi Abdi Perdanawati

and Rudy Akhwadhy

1,2

Faculty of Science and Tecnology Islamic University of Sunan Ampel Surabaya,,Jalan Ahmad Yani 117,Surabaya

Badan riset Sumber Daya Manusia, Kementrian Kelautan dan Perikanan, Jalan Pasir Putih I, Ancol, Jakarta

Keywords: Reclamation, Current, Jakarta Bay, Mike21.

Abstract:

Currently, the land reclamation of Jakarta bay as the manifestation of Presidential Regulation No.

25 of 1995 consists of 4 islands (Named: C (a half), D, G (a half), and N). The land reclamation

may cause effects and changes in water condition, especially in hydrodynamic condition.

Understanding on effects of reclamation is very important as an effort to manage coastal zone. This

research investigates the possible effects in tidal current at two conditions: current condition (4

islands) and master plan (17 islands). The analysis is divided into 3 areas: marine tourism area,

port area, and marine life area. The simulation used mike 21 with hydrodynamic module. The

simulation has shown that current dominantly goes to the west in highest sea level and dominantly

goes to the east in lowest sea level. The fastest current during north-west monsoon occurs in marine

tourism area. The fastest current during south-east monsoon occurs in marine biota area. Current

speed if master plan (17 islands) is implemented will be slower than current condition.

1 INTRODUCTION

Jakarta Bay is a part of Java sea located in the north

of DKI Jakarta, Indonesia. This bay is a shallow water

area with an average depth of 15 meters

(Coordinating Ministry for Coastal Integrated

Economic Development, Capital City, 2014).

Population density in DKI Jakarta is one of the factors

causing land shortages. Therefore, reclamation is

considered by the DKI provincial government to be

one of the choices to overcome this problem.

Reclamation in DKI Jakarta is the addition of 17

islands covering an area of 5,189 Ha (Agus, 2016).

Reclamation in the Jakarta Bay is feared to change

the flow pattern. Ocean currents play an important

role in the processes of biology, physics, and

chemistry that occur in the sea (Ismunarti, 2013). The

problems that occur in Jakarta Bay can be studied

with Mike21 software. In general, this software is

more friendly on graphic interfaces, easy to use /

simple, and able to be undone. It is very different from

similar software such as SMS (Surface

waterModeling System). This software is a collection

of several simulation modules to predict the rate of

sedimentation.

The purpose of this study is to determine the

current pattern before and after reclamation is

finished.

2 METHODS

Research of hydrodynamic modelling in the Jakarta

Bay (figure 1A) was carried out for 6 months, from

January - March (west season) and from July -

September (east season). Modelling used Mike21

software with a Hydrodynamic module.

The monitoring point was based on the area that

entered the quality standard according to KEPMEN

LH No. 51 of 2004 which was then selected based on

field conditions. Based on the minister's decision, the

bay area of Jakarta is divided into 3 parts, namely:

marine tourism area, port area, and water biota area.

Tourist area was with 5 monitoring points, port area

was with 23 monitoring points, and water biota area

was with 25 monitoring points.



Saputra, R., Perdanawati, R. and Akhwadhy, R.

Hydrodynamic Modelling using Software of Mike21 in the Land Reclamation of Jakarta Bay: Current Condition and Master Plan.

DOI: 10.5220/0008907400002481

In Proceedings of the Built Environment, Science and Technology International Conference (BEST ICON 2018), pages 367-377

ISBN: 978-989-758-414-5

367



The monitoring point was based on the area that

entered the quality standard according to KEPMEN

LH No. 51 of 2004 which was then selected based on

field conditions. Based on the minister's decision, the

bay area of Jakarta is divided into 3 parts, namely:

marine tourism area, port area, and water biota area.

Tourist area was with 5 monitoring points, port area

was with 23 monitoring points, and water biota area

was with 25 monitoring points.

2.1 Model Parameter

Model parameters used the Hydrodynamic module.

The hydrodynamic module was carried out in 3

different months, namely during the west season

starting from January to April 2016 and during the

east season starting from July 2016 to October 2016.

The results of the hydrodynamic module will provide

output in the form of current speed, current direction,

and water level elevation.



2.2 Model Design

Model area used was the Jakarta Bay area which

were divided into 2 models namely post reclamation

(figure 2) and master plan (Figure 3). In post

reclamation condition, there are reclaimed islands C

(half), D, G (half), and N. The depth in these

conditions ranges from -2 meters to -28 meters. In

the master plan, there are 17 reclamation islands as

shown above. The depth in this condition ranges

from -2 meters to -35 meters.

In the initial stages of modelling, the most

important part is the mesh editing process. Mesh

elements are automatically formed based on

predetermined coastline data and boundary

conditions. In this study, editing mesh (Figure 4) used

triangular meshing model with a minimum angle of

28 °. The area where meshing reclamation island will

be built is made increasingly tight so that the level of

accuracy is higher.

Figure 1: A. Research Location map

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Figure 2. post reclamation of Jakarta Bay

Figure 3. post reclamation of Jakarta Bay

Figure 4. Meshing Model

3. RESULT

3.1 Wind

Wind data is needed to determine the distribution of

wind direction from the wind speed that occurs at the

research location. Wind data used were wind data

from 2013 to 2017 obtained from the Jakarta

Meteorology and Geophysics Agency (BMKG).

Wind speed and direction in Jakarta Bay from 2013

to 2017 predominantly came from the east with a

speed of 3.45 m / s. Wind speed and direction in

Jakarta Bay during western season were

predominantly originated from the east and northeast

with a speed of 3.85 m / s. Whereas during the east

season, the wind speed and direction in the Jakarta

bay predominantly came from the southeast with a

speed of 3.65 m/s.

3.2 Tide

Tidal predictions used NAOTIDE software and were

compared with observational data in the Jakarta Bay.

Tides in the Jakarta Bay are single daily type with

Formzahl number 5.97. The highest elevation is

0.45185 m, while the lowest elevation is -0.44238 m.

The validation and the tide observation resulted in an

RMSE value 0.00286. Small RMSE value indicates

that the tidal prediction value has a relatively small

error rate (Syahputra, 2016). This means that tidal

prediction data can be used.

3.3 Current

Current data used were measurement data from

BRSDM-KP which use ADCP (Acoustic Doppler

Current Profiler). Data were taken in June 2015 with

coordinates of -6.043011 ° LS and 106.734212 ° BT.

The current at the observation point was dominantly

from the northwest, which is consistent with the

research conducted by Aprilia (2017). The maximum

speed reached 12.07 m / s and the minimum speed

was 0.1 m / s, while the average speed was 4.843 m /

s. As for current speed validation, Jason-2 altimetry

satellite data was used (Aprilia, 2017). The RMSE

value of 0.023 was obtained. According to Syahputra

(2016), small RMSE value indicates that the value of

the model results has a relatively small error rate. This

means that the current model data from the Mike21

software can be used.

3.4 River Discharge

River discharge data used for input in this study were

data of average river discharge into the Bay of

Jakarta. Estuaries used included estuary BKT, Muara

Ancol, Muara Waduk Pluit, Muara Angke, and Muara

Cengkareng Drain. The biggest river debit was the

discharge from Angke estuary which was 26.71 m3 /

s, while the lowest estuary discharge was the BKT

estuary with 3.37 m

/s.



3.5 Hydrodynamic Modelling from

Post-Reclamation and Master Plan

Hydrodynamic modelling results were obtained from

the overview in the current pattern of Jakarta bay.

Hydrodynamic Modelling using Software of Mike21 in the Land Reclamation of Jakarta Bay: Current Condition and Master Plan

369

General description of the current condition after

recent reclamation at the highest tide in the bay of

Jakarta is dominantly towards the east and the

northeast (Figure 5.a). The smallest current velocity

is between 0 m / s - 0.098 m / s, while the biggest

speed is between 0.361 m / s - 0.427 m / s. Whereas

the current conditions if master plan is fully

implemented in the Jakarta bay are dominantly to the

eastward (figure 5.b). According to Bakrie (2017),

current patterns are influenced by wind direction and

wind speed, besides bathymetry profiles also affect

current patterns. The minimum current velocity is

between 0 m / s - 0.120 m / s, while the maximum

current is between 0.240 m / s - 0.360 m / s General

description of the post-reclamation condition when

the lowest ebb of the flow in the Jakarta bay

predominantly headed west can be seen in Figure 6.b.



Figure 5. Current pattern at the highest tide in the west season: a) post reclamation b) master plan

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Figure 5. Currentpatternatthehighesttideinthewestseason:a)postreclamationb)masterplan



Figure6.Currentpatternatthelowesttideinthewestseason:a)postreclamationb)masterplan

This is directly proportional to the wind pattern

during the west season that is dominantly from east to

west. According to Bakrie (2017), current patterns are

influenced by wind direction and wind speed, besides

bathymetry profiles also affect current patterns. The

smallest current velocity is between 0 m / s - 0.096 m

/ s, while maximum current velocity was between

0.386 m / s - 0.483 m / s. The current pattern at the

lowest ebb tide in the Jakarta bay was dominantly to

the northwest - west (figure 6.b). This is because the

geographical location of the Jakarta Bay, between the

east end and the west end, is not parallel with the west

end and is slightly down south. The minimum current

velocity was between 0 m / s - 0.120 m / s, while the

maximum current was between 0.120 m/s - 0.240 m/s.

General description of post-reclamation flows

during the east season when the highest tides in the

Jakarta bay predominate towards the west and

northwest can be seen in Figure 7.b. This is due to the

wind coming from the southeast. According to Bakrie

(2017), current patterns are influenced by wind

direction and wind speed, besides bathymetry profiles

also affect current patterns. The smallest current

velocity was between 0 m / s - 0.151 m / s, while the

biggest speed was between 0.151 m / s - 0.302 m / s.

Figure 7 b is a general description of the

master plan condition during the east season when the

highest tide in the bay of Jakarta is dominantly

towards the west and the northwest. This is due to the

wind coming from the southeast. The smallest current

Hydrodynamic Modelling using Software of Mike21 in the Land Reclamation of Jakarta Bay: Current Condition and Master Plan

371

velocity was between 0 m / s- 0.149 m / s, while the

largest speed was between 0.148 m / s - 0.297 m / s.

Figure 7. Current pattern at the highest tide during the east season: a) post reclamation b) master plan

Figure 8.a shows general description of post-

reclamation current conditions in the east season

when the highest tide flows in the Jakarta Bay

predominantly head towards the east and the

northeast. This is due to the wind coming from the

southeast. The smallest current velocity was between

0 m / s - 0.151 m / s, while the biggest speed was

between 0.452 m / s - 0.603 m / s. Whereas Figure 8.b

is a general description of the current during the east

season when the lowest ebb flows in the bay of

Jakarta are dominantly towards the east and the

northeast.

This is due to the wind coming from the

southeast. According to Bakrie (2017), current

patterns are influenced by wind direction and wind

speed, besides bathymetry profiles also affect current

patterns.

The smallest current velocity was between 0 m / s

- 0.140 m / s, while the largest speed was between

0.560 m / s - 0.700 m / s.

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During the west season, the current dominantly

goes to the east, while when it recedes, the current is

dominantly to the west. This is due to the wind during

the dominant western season heading east. During the

east season, the current is dominantly towards the

west, while when it recedes, the current is dominantly

to the east. This is due to the wind during the east

season heading west. According to Bakrie (2017),

current patterns are influenced by wind direction and

wind speed, besides bathymetry profiles also affect

current patterns.

3.6

Hydrodynamic in The Marine Tourism

Area

The maritime tourism zone includes Ancol Beach

area and Pantai Indah Kapuk. Figure 7 shows that

during the west season, the average current velocity

in the master plan condition experienced an

insignificant decrease compared to in the post

reclamation condition. This is because the point of

monitoring, that is in the marine tourism area, is far

from the reclamation island plan. Whereas during the

east season, the average speed in the aster plan

experienced an insignificant decrease compared to in

the post reclamation condition. However, at the

observation point 27, there was a significant

decreaseincurrentvelocity.

This is because the observation point 27 is between

the reclamation islands J and L and the distance

between reclamation islands J and L is relatively

narrow, so that the current speed slows down.

According to Kurniawati (2017), in the vicinity of

Figure 8.

Current pattern at the lowest tide during the east season: a) post reclamation b) master plan

Hydrodynamic Modelling using Software of Mike21 in the Land Reclamation of Jakarta Bay: Current Condition and Master Plan

373

reclamation islands there was a flow of currents

because of the obstructed landscape of the island and

because the area blocked by the reclamation island

had a small tendency.

Figure 9.

Currentconditioninthemarinetourism

are

3.7 Hydrodynamic in The Port Area

The Port Zone includes Tanjung Priok Port, Nizam

Zaman Port, Muara Baru, and Muara Kamal Port.

Figure 10 shows that during the west and east

seasons, average velocity in the master plan is smaller

than the current in the time of post reclamation. This

is because there were several monitoring points in the

port area which experienced a significant decline. At

the observation point 8 during the east and west

seasons, there was a significant change in current

patterns. This happened because in the pre and post

reclamation conditions, there was no reclamation

island, while in the condition of the master plan, the

current pattern changes because of the islands E and

At the observation point 17 during the east and

west seasons, there was a significant change in

current patterns. This was because point 17 is

between the P and Q reclamation islands where the

distance between the two reclaimed islands is

relatively narrow so that it forms something like a

canal. At observation point 22 during the east and

west seasons, there was a significant change in

current velocity. This was because observation of

point 22 is at the end between N and O reclamation

islands. At observation point 29 during the east and

west seasons, there was a significant change in

current velocity. Meanwhile in the condition of the

master plan, the current tended to be slower than in

the post-reclamation condition. This happens because

point 29 affects the reclamation island F. At the

observation point 30 during the east and west seasons,

there was a change in the flow velocity due to the

reclamation island H.

In the port area, the current has been weakening

since the reclamation started. This is because the

Figure 10.

Currentconditionintheportarea

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currents that hit the reclamation island cause small

currents. According to Kurniawati (2017), in the

vicinity of reclamation islands there was a flow of

currents because of the obstructed landscape of the

island and because the area blocked by the

reclamation island had a small tendency.

3.8

HydrodynamicinTheMarineBiotaArea

Marine biota zones cover zones where the marine

biota lives. Figure 11 shows that during the west and

east seasons, average velocity in the master plan

condition is smaller than the current at the time of post

reclamation. This was because there are several

monitoring points in the port area which experienced

a significant decline. At the observation point 33

during the east and west seasons, there was a

significant change in speed and current pattern. This

is because the observation point 33 is at the end

between reclaimed islands D and E. At the

observation point 35 during the east and west seasons,

there was a change in the current pattern. This

happened because of the reclamation islands B and C.

At the observation point 36 during the east and

west seasons, there was a change in the flow velocity

due to the reclamation of islands A and B so that the

current velocity becomes weak.

3.9 Hydrodynamic in Any Area

Figure 12 shows during the west season, the velocity

of currents in the maritime tourism zone is greater

than it is in the port area and marine biota area.

Whereas during the east season, the current velocity

in the marine biota area is greater than it is in the

marine tourism area and port area.

At the observation point 37 during the east and

west seasons, there was a change in the flow pattern

due to the reclamation islands A and B. At the

observation point 38 during the east and west seasons,

there was a change in the current pattern. This

happened because of the reclamation island A, the

current speed at point 38 becomes slower because the

point is along the coast and adjacent to the

reclamation island A.

In the area of marine biota, the current has been

weakening since the reclamation process started. This

is because the currents that hit the reclamation island

cause small currents. According to Kurniawati

(2017), in the vicinity of reclamation islands there is

a flow of currents due to blocked islands and the area

blocked by reclaimed islands that has a small

tendency.

The decrease in current velocity occurs along with

the reclamation island. According to Kurniawati

(2017), in the vicinity of reclamation islands there is

a deflection of the flow because it is blocked by the

Figure 11. Current condition in the marine

iota area

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span of the island and the area blocked by the

reclamation island has a small tendency.



Figure 12. Current condition any area



3.10 Impact of Changes on Current

Patterns



The impact of changes on current patterns caused by

reclamation is very influential to the physical,

chemical and biological activities that occur at sea.

According to Ismunarti (2013), ocean currents play

an important role in the processes of biology, physics,

and chemistry that occur at sea. In addition, the

weakening of the current will also result in high

sedimentation rates. According to Miftachurraazaq

(2017), if the flow is faster, the sediment

concentration will decrease, whereas if the current is

weak, the sediment concentration will increase.

4 CONCLUSIONS

Current modelling results of marine tourism areas

current velocity in post-reclamation conditions

during the western season is greater than it is in

master plan conditions. The current velocity in port

area in post-reclamation conditions is greater than it

is in the master plan conditions, while in the marine

biota area, the current velocity in post-reclamation

conditions is greater than it is in the master plan

condition. Whereas during the eastern season, the

current velocity of the marine tourism area in the

post-reclamation condition is greater than it is in the

master plan condition. Current velocity of the port

area in the post-reclamation condition is greater than

it is in the master plan condition, and in the marine

biota area, the current velocity in the post-reclamation

condition is greater than it is in master plan condition.

This is caused by the bending of the current due to the

reclamation island so that the current becomes small.

During the west season, current speed of the

marine tourism area is faster than those of the port

area and marine biota, while during the east season,

the current Speed in the marine biota area is greater

than it is in the marine tourism area and port area.

ACKNOWLEDGEMENTS

I would like to thank BRSDM-KP for supplying data

and making software mike21. I also want to show my

gratitude to BMKG Jakarta for supplying data, and to

Islamic University of Sunan Ampel Surabaya for

permission to use laboratory of computer to run this

software.

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