Tide, Tidal Current and Sediment Transport in the Mahakam ... · Tide, Tidal Current and Sediment...

Tide, Tidal Current and Sediment Transport in the Mahakam estuary, y,

East Kalimantan, Indonesia

Idris MandangIdris MandangInterdisciplinary Graduate School of Engineering Science

Department of Earth System Science of Technologyp y gyKyushu University, Japan

Description of Mahakam estuary and domain model

The Mahakam Delta, located on theeast coast of Kalimantan, Indonesia, iseast coast of Kalimantan, Indonesia, isan active delta system which hasformed in humid tropical environmentunder condition of relatively high

MahakamRiver

Kuching High

y gtides, low wave-energy, and largefluvial input.Malaysia

KutaiLakes

MahakamDelta

A

Tidal processes control the sedimentdistribution patterns in the deltamouth and are responsible for the

Sumatera

Makassar

Strait0 50 100

km

Adang Fault

pflaring estuarine-type inlets andnumerous tidal flats.

The Mahakam estuary is influencedby tide and tidal current from MakasarStrait.Strait.

Objectivesj

The thesis aims:To increase the understanding of physical mechanismcontrolling the transport of suspended sediment. Relevant

h i l l d h h d d i dphysical processes related to the hydrodynamics, andsuspended sediment transport are described based onobservation and numerical modeling studiesobservation and numerical modeling studies.

Objectivesj

The specific objectives of this study are:

1. To provide a qualitative description of the generalcirculation pattern, suspended sediment transport in theMahakam estuary.

2. To develop a numerical model of the hydrodynamic,and cohesive sediment transport by incorporating theand cohesive sediment transport by incorporating theinfluences by tides and river discharge at the openboundary and upstream, respectively.y p , p y

The thesis in the Mahakam estuary is ydivided into two part :

Part 1

Tide and Tidal CurrentPart 2

S di t t tSediment transport

Part 1

Tide and Tidal Current

Objective

We will simulate tide and tidal current by aWe will simulate tide and tidal current by anumerical model, and the calculated resultswill be compared with the observation data inwill be compared with the observation data inthe Mahakam estuary.

Observation

Time series of sea surface elevation andc rrent ere obtained b the IMAUcurrent were obtained by the IMAU(Institute for Marine and AtmosphericResearch Utrecht University, theNetherland) which conducted the field Muara JawaNetherland), which conducted the fieldobservation in the Mahakam delta duringthe period of 30 June – 08 July 2003 (thesouth-east monsoon).

Muara Jawa

)

Sea surface elevation and current velocitymeasured by the pressure sensor andeasu ed by t e p essu e se so a dADCP (the Acoustic Doppler CurrentProfiler), manufactured by RDI.

The data were sampled at Muara Jawa atthe depth of 4.0 m from the surface.

Numerical ModellingNumerical Modelling

The development of ECOMSED (EstuarineCoastal and Ocean Modeling System withg ySediment) has its origins in the mid 1980’s withthe creation of the Princeton Ocean Model(Bl b d M ll 1987) d it i f(Blumberg and Mellor, 1987) and its version forshallow water environments – rivers, bays,estuaries the coastal ocean reservoirs andestuaries, the coastal ocean, reservoirs andlakes- named ECOM (Blumberg, 1996).

Hydrodynamic Model• Governing Equations 2D Model

• Continuity equation :

∂∂∂ VDUD η 0=∂∂+

∂∂+

∂∂

tyVD

xUD η

Equation of motion :

(1)

• Equation of motion :

fVUUU b ∆∂∂∂∂ τη2

UADx

gVfyVU

xU

tU

Ho

bx ∆++∂∂−=−

∂∂+

∂∂+

∂∂

ρτη

(2)

VADy

gUfyV

xVU

tV

Ho

by ∆++∂∂−=+

∂∂+

∂∂+

∂∂

ρτη2

(3)

ParametersU and V : the vertically integrated velocities in x and y direction [m/s] D : the total depth (= H + η) H : the depth η : the water of surface elevation τｂｘ and τｂy

:the bottom stress in x and y direction( ( )2220 VUUb += γρ

d ( )222 VUV )and ( )2220 VUVb += γρ )

0ρ : the density of water (=1024.78 kg/m3)

2bγ : the bottom frictional coefficient (= 0.0025)

g : the gravitational acceleration [m/s2] f : the Coriolis parameter (= 2Ω sin φ; Ω = 7.27 x 10-5/s and φ

is the latitude) η : the surface elevation ∆

: the Laplace Operator for 2 Dimensional (= 2

2

2

2

yx ∂∂+

∂∂

)

AH : the coefficient of horizontal eddy viscosity [m2/s] The horizontal eddy viscosity are given on the basis of Smagorinsky formula [1963],

( ) 2/122 ⎤⎡( ) 2222/ ⎥

⎦

⎤⎢⎣

⎡⎟⎠⎞⎜

⎝⎛

∂∂+⎟

⎠⎞⎜

⎝⎛

∂∂+∂

∂+∂∂∆∆= y

Vy

Uy

Vx

UyxCAH where C is a constant (= 0.20)

Model application to the Mahakam estuaryModel application to the Mahakam estuary

Numerical Experimentu e ca pe e• The computational domain is the Mahakam

estuaryestuary .• Grid sizes are ∆x = ∆y = 200 m. • The time step used in the simulation is 4 s.• The integration was carried out for 15 days

（27 June – 12 July 2003). • The surface wind stress is neglected. g• The water density is considered to be

constantconstant.

Bathymetric map of Mahakam estuaryBathymetric map of Mahakam estuary

Sebulu150

(m)

Tenggarong

Muara Badak

125

150

Tenggarong

SamarindaMuara Kaeli

Mahakam River100

N Pulau NubiMuara Bayur

75

Makassar Strait

Muara Bayur

50

Muara Pegah Maka

0 10 20 km 25

Open boundary

Open boundary 3

Boundary ConditionBoundary Condition• Tidal elevation used in open boundary condition on 4 dominant

h i tit t (M S K O )harmonic constituents (M2, S2, K1, O1)

Constituent Amplitude and

PhSta. 1 Sta. 2 Sta.3 Sta.4 Sta.5

PhaseM2 Amplitude (m) 0.699 0.699 0.699 0.646 0.647

Phase (deg) 276.88 276.04 276.04 278.38 278.37ase (deg) 76.88 76.0 76.0 78.38 78.37

S2 Amplitude (m) 0.465 0.468 0.468 0.478 0.478

Phase(deg) 322.57 322.54 322.54 322.57 322.50

K1 Amplitude (m) 0.221 0.224 0.224 0.211 0.211

Phase (deg) 159.02 160.27 160.27 156.66 156.40

O Amplitude (m) 0 164 0 165 0 165 0 159 0 159O1 Amplitude (m) 0.164 0.165 0.165 0.159 0.159

Phase (deg) 139.36 140.45 140.45 137.22 137.03

Table 1. The Amplitudes and phase (referenced at GMT + 08.00) of the 4 dominant harmonic constituents in open boundary condition from ORITIDE Prediction Model (ORI, Tokyo Univ.)

Boundary ConditionBoundary ConditionRiver discharge in upstream boundary

2 5 0 0

3 0 0 0

1 5 0 0

2 0 0 0

harg

e (m

3 /s)

5 0 0

1 0 0 0

Rive

r dis

ch

J a n F e b M a r A p r M a y J u n J u l A u g S e p O c t N o v D e c0

M o n t h s

The monthly river discharge (m3/s) data of Mahakam river（from Research and Development Irrigation Ministry Public Work, Republic of Indoenesia)

20 0 3/The given river discharge is 2040 m3/s.

Simulation ResultsSimulation ResultsVerification of elevation between the observation data (IMAU Utretch Univ.) and the simulation results at Muara Jawa; for the period of 30 June to 08 July 2003

Tenggarong

Sebulu

Tenggarong

Sebulu

Mahakam River

gg gSamarinda

Muara JawaMahakam RiverMahakam River

gg gSamarinda

Muara JawaThe RMS error for both datasets was 0.15 m

N

0 10 20 km

Muara Pegah

N

0 10 20 km

N

0 10 20 km

Muara Pegah

Open BoundaryOpen Boundary

Simulation ResultsSimulation ResultsVerification of the current velocity component U (x direction, east (+) – west (-)) between the observation data (IMAU Utretch Univ.) and the simulation results at Muara Jawa at depth of 4.0 m from the surface; for period of 30 June to 08 July 200ua a Ja a a dep o 0 o e su ace; o pe od o 30 Ju e o 08 Ju y 00

Tenggarong

Sebulu

Tenggarong

Sebulu

Mahakam River

gg gSamarinda

Muara JawaMahakam RiverMahakam River

gg gSamarinda

Muara JawaRMS error = 0.05 ms-1

N

0 10 20 km

Muara Pegah

N

0 10 20 km

N

0 10 20 km

Muara Pegah

Open BoundaryOpen Boundary

Simulation ResultsSpectral analysis of the time series of observed and simulation results

Simulation Results• Spectral analysis of the time series of observed and simulation results

(log 10) (log 10)

Current velocity Elevation

0.1

M4O1 and K1

M2 and S2

( g )

0.01

(log 10)

M2 and S2

M4

1E-3

0.01M4

gnitu

de (c

m)2

1E-4

1E-3O1 and K1

nitu

de (c

m/s

)2

1E-4

mag

Observation dataSimulation Results

1E-5

mag

n

Observation DataSimulation Results

0 5 10 15 20 25 30 35 40 45 50 55 60 651E-5

period (hour)

Simulation Results

0 5 10 15 20 25 30 35 40 45 50 55 60 651E-6

period(hour)

Simulation Results

Simulation ResultsSimulation Results

The temporal variation of elevation along the Mahakam Estuary and open boundary from 2 to 3 July 2003

Simulation Results• The spatial variation tidal amplitudes and cross-sectional area along the axis of the

Mahakam Estuary from the Sebulu to open boundary

Horizontal distance from Sebulu towards open boundary (km) Horizontal distance from Sebulu towards open boundary (km)

Simulation Results• The spatial variation tidal current amplitudes and cross-sectional area along the axis of

the Mahakam Estuary from the Sebulu to open boundary

Horizontal distance from Sebulu towards open boundary (km) Horizontal distance from Sebulu towards open boundary (km)

Simulation Results• The spatial variation of M4/ M2 tidal current amplitudes and cross-sectional area along the axis of

the Mahakam Estuary.

1.85

Tenggarong

Sebulu

Tenggarong

Sebulu

Mahakam River

N

Samarinda

Muara JawaMahakam River

N

Mahakam River

N

Samarinda

Muara Jawa

N

0 10 20 km

Muara Pegah

N

0 10 20 km

N

0 10 20 km

Muara Pegah

Open BoundaryOpen Boundary Horizontal distance from Sebulu towards open boundary (km)

Simulation Results• Spatial variation of mean sea level and the averaged tidal current kinetic energy in the Mahakam

Estuary. I dis

Tenggarong

Sebulu

Tenggarong

Sebulu

Mahakam River

N

Samarinda


N

Mahakam River

N

Samarinda

Muara Jawa

N

0 10 20 km

Muara Pegah

N

0 10 20 km

N

0 10 20 km

Muara Pegah

Open BoundaryOpen Boundary Horizontal distance from Sebulu towards open boundary (km)

Simulation Results

(a) (b)

Tide-driven circulation during for : (a) Maximum flood in spring tide (b) High water in spring tide

Simulation Results

(c) (d)

Tide-driven circulation during for : (c) Maximum ebb in spring tide (d) Low water in spring tide

Conclusions The RMS error in the model elevation and current velocity are 0.15m and 0.05m/s, respectively. The semidiurnal (M S ) tidal amplitude peaks between the open boundaryThe semidiurnal (M2, S2) tidal amplitude peaks between the open boundary and Muara Pegah and then it begins to decrease steadily upstream of the Muara Pegah along main stream of the Mahakam River.The diurnal (K1,O1) tidal amplitude peaks between the open boundary and ( 1, 1) p p p yMuara Pegah. The decrease of amplitude is smaller than that of the semi diurnal.The tidal amplitude distortion (M4/M2) in the Mahakam estuary is less than 0 30.3. The currents in Mahakam Delta waters are mostly affected by tides and river flow.When the flood tide from Makassar Strait occur, the current flows to the delta waters, and vice versa in ebb tide.In this numerical simulation, the results clearly indicate that tide is the main driving force affecting the sea level and current in the Mahakam estuary.

Part 2

Sediment Transportp

Objective

To identify the circulation pattern of the waterand cohesive sediment transport by a 3Dhydrodynamic baroclinic circulation model,y y ,and the calculated results will be comparedwith the observation data in the Mahakamwith the observation data in the Mahakamestuary.

Observation

Time series of sea surface elevation andcurrent were obtained by the IMAU (Institute

Muara Jaway (

for Marine and Atmospheric Research UtrecthUniversity, the Netherland), which conductedthe field observation in the Mahakam deltaduring the period of 30 June – 08 July 2003during the period of 30 June 08 July 2003(the south-east monsoon).

Sea surface elevation and current velocityd b th d ADCPmeasured by the pressure sensor and ADCP

(the Acoustic Doppler Current Profiler),manufactured by RDI.

The suspended sediment concentration weremeasured by seapoint Optical BackscatterSensor (OBS) was attached to the CTD(Conductivity Temperature and Depth)(Conductivity, Temperature, and Depth)probe.

The time series data were sampled at MuarapJawa at the depth of 4.0 m from the surface.

Numerical ModelingNumerical Modeling

The development of ECOMSED (Estuarine Coastal andO M d li S t ith S di t) h it i i iOcean Modeling System with Sediment) has its origins inthe mid 1980’s with the creation of the Princeton OceanModel (Blumberg and Mellor, 1987) and its version for( g , )shallow water environments – rivers, bays, estuaries, thecoastal ocean, reservoirs and lakes- named ECOM(Blumberg 1996)(Blumberg, 1996).The ECOMSED model is a three-dimensional finitedifference baroclinic model system for hydrodynamic andd e e ce ba oc c ode syste o yd ody a c a dcohesive sediment transport model .

Hydrodynamic Model• Governing Equations for 3D Model

• Continuity Equation :∂∂∂ WVU

• Equation of Motion :

(1)0=∂

∂+∂∂+

∂∂

zW

yV

xU

⎞⎜⎜⎛ ⎞

⎜⎜⎛

∂∂+

∂∂

∂∂+

⎠⎞

⎜⎝⎛

∂∂

∂∂+

⎠⎞

⎜⎝⎛

∂∂

∂∂+

∂∂−=

−∂

∂+∂

∂+∂

∂+∂

∂

VUAUAUAP

fVzUW

yUV

xUU

tU

MMV 21 (2)⎠

⎜⎝ ⎠

⎜⎜⎝ ∂∂∂⎠

⎜⎝ ∂∂⎠

⎜⎝ ∂∂∂ xyyxxzzx MMV

0ρ( )

+∂∂+

∂∂+

∂∂+

∂∂ fU

zVW

yVV

xVU

tV

⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

∂∂+⎟⎟

⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂+

∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂+

∂∂−=

yVA

yxV

yUA

xzUA

zyP

MMV 21

0ρ (3)

∫0

d∫−

+= 00z

dzBgP ρηρ

gB0

0

ρρρ −

=

(4)

(5)0ρ

and, the equations transport of temperature and salinity as follows below,

ρ0ρ

⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂=

∂∂+

∂∂+

∂∂+

∂∂

yTA

yxTA

xzTK

zzTW

yTV

xTU

tT

HHV

⎞⎛ ∂∂⎞⎛ ∂∂⎞⎛ ∂∂∂∂∂∂ SSSSSSS

(8)

⎟⎠

⎞⎜⎜⎝

⎛∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂=

∂∂+

∂∂+

∂∂+

∂∂

ySA

yxSA

xzSK

zzSW

ySV

xSU

tS

HHV (9)

where, U V W : the velocity components along x y z directions respectively [ms-1]U, V, W : the velocity components along x, y, z directions respectively [ms ]T : the temperatureS : the salinityP : the pressureρ0 : the reference density (=1024.78 kg m-3)g : the gravitational acceleration [m s-2]η : the surface elevationB : the buoyancyB : the buoyancyAV : the vertical eddy diffusivity of turbulent momentum mixing[m2/s]KV : the vertical eddy diffusivity for turbulent momentum mixing of

heat and salt [m2/s]

AM : the horizontal eddy viscosity for momentum, [m2/s]AH : the horizontal diffusion coefficient for salinity and temperature [m2/s]

f : th C i li t ( 2Ω i φ Ω 7 27 10 5/ d φ i th l tit d )f : the Coriolis parameter (= 2Ω sin φ; Ω = 7.27 x 10-5/s and φ is the latitude)

The Suspended Sediment Transport ModelThe transport of suspended sediment is described by the following advection –dispersion equations

( )−∂+∂+∂+∂ CWWVCUCC s( )

⎟⎠⎞

⎜⎝⎛

∂∂

∂∂+⎟⎟

⎠

⎞⎜⎜⎝

⎛∂∂

∂∂+⎟

⎠⎞

⎜⎝⎛

∂∂

∂∂=

∂+

∂+

∂+

∂

zCK

zyCA

yxCA

x

zyxt

VHH

s

(6)

⎠⎝⎠⎝⎠⎝ yyBoundary Condition

zzCK V →=

∂∂ ,0 η (7)

Where

HzDEzCK kkV −→−=

∂∂ ,

C : Cohesive sediment concentration [mg l-1]

(8)

Where, C : Cohesive sediment concentration [mg l ]

U, V, W : the velocity components along x, y, z directions respectively [ms-1]

KV : the vertical eddy diffusivity [m2/s]

AH : the horizontal diffusivity [m2/s]

Ek and Dk : the resuspension and deposition flux of cohesive sediment

η : the water surface elevation [m]

H : the bathymetric depth below the datum

Model ApplicationPhysical setting• The computational domain is the Mahakam estuaryThe computational domain is the Mahakam estuary .• Grid sizes are ∆x = ∆y = 200 m. • 3 vertical σ- levels3 vertical σ levels

Temporal setting

• The time step used in the simulation are : • ∆tE (external mode, 2-D) = 4 s, and ∆tI (internal mode,

3-D) = 40 sTh d l i i ll t t i l t th i d• The model was originally set up to simulate the periods June 27, 2003 – July 12, 2003 (15 days)

Model Parameters

Bottom friction coefficient = 0.009Bottom roughness coefficient = 0.0014 mHorizontal mixing is used in Smagorinsky ‘s formula for mixing :for mixing :

( )2/1222

2/ ⎥⎦

⎤⎢⎣

⎡⎟⎠⎞⎜

⎝⎛

∂∂+⎟

⎠⎞⎜

⎝⎛

∂∂+∂

∂+∂∂∆∆== y

Vy

Uy

Vx

UyxAA HM α

where α = 0.22Vertical mixing are obtained through the 2 5 level turbulence closure

⎦⎣ ⎠⎝⎠⎝

Vertical mixing are obtained through the 2.5 level turbulence closurescheme developed by Mellor and Yamada (1982)

The Forcing Data

Open Boundary ConditionTidal elevation used in open boundary condition on 4 dominant harmonic

tit t (M S K O )constituents (M2, S2, K1, O1)

Constituent Amplitude and Sta. 1 Sta. 2 Sta. 3 Sta. 4 Sta. 5Phase

Sta. 1 Sta. 2 Sta. 3 Sta. 4 Sta. 5

M2 Amplitude (m) 0.699 0.699 0.699 0.646 0.647

Phase (deg) 276 88 276 04 276 04 278 38 278 37 Phase (deg) 276.88 276.04 276.04 278.38 278.37

S2 Amplitude (m) 0.465 0.468 0.468 0.478 0.478

Phase(deg) 322.57 322.54 322.54 322.57 322.50

K1 Amplitude (m) 0.221 0.224 0.224 0.211 0.211

Phase (deg) 159.02 160.27 160.27 156.66 156.40

O1 Amplitude (m) 0.164 0.165 0.165 0.159 0.159

The Amplitudes and phase (referenced at GMT + 08.00) of the 4 dominant harmonic constituents in open boundary condition from ORITIDE Prediction Model

p ( )

Phase (deg) 139.36 140.45 140.45 137.22 137.03

open boundary condition from ORITIDE Prediction Model (ORI, Tokyo Univ.)

The Forcing Data (Continued)

Open Boundary ConditionTemperature and Salinity Boundary Conditionp y y

Station Temperature (0C) Salinity (PSU) Station

∆σ1 ∆σ2 ∆σ3 ∆σ1 ∆σ2 ∆σ3

Sta. 1 28.14 27.03 24.11 32.04 32.05 34.33

Sta. 2 28.04 27.21 23.64 33.55 33.94 35.00

Sta. 3 28.04 27.23 23.32 33.05 33.07 33.08

Sta. 4 28.06 27.12 24.20 33.25 33.61 33.97

Sta. 5 28.16 27.05 23.88 21.01 21.01 21.02

∆σ1 = ∆σ2 = ∆σ3 = the sigma level


Upstream BoundaryFreshwater Inflow = 2040 m3S-1

2 0 0 0

2 5 0 0

3 0 0 0

s)

1 0 0 0

1 5 0 0

2 0 0 0

ver d

isch

arge

(m3 /s

J a n F e b M a r A p r M a y J u n J u l A u g S e p O c t N o v D e c0

5 0 0

Riv

The monthly river discharge (m3/s) data of Mahakam river（from Research and Development Irrigation Ministry Public Work,

Republic of Indoenesia)

T t 29 C

M o n t h s

Temperature = 29oCSalinity = 0.01 psu


Sediment Parameters

Settling velocity Ws = 35 (C.τ )0.20 µm s-1

Critical shear stress for deposition τcd = 1 dyne cm-2

Thickness of sediment bed = 10 cmThickness of sediment bed 10 cm

Critical shear stress for erosion τce = 1 dyne cm-2

Initial condition = 8 mg L-1

Open boundary condition = 1 mg L-1

Upstream boundary condition = 170 mg L-1 (Allen, 1985)

Erosion potential

, τb > τce⎟⎠

⎞⎜⎜⎝

⎛ −= cb

mTa

τττε 0

where, a0 = 2.5 , m = 0.5 , n = 2.5 , Td= the time of consolidation, 1 – 7 days

⎠⎜⎝ c

mdT τ

Td the time of consolidation, 1 7 days τb = bed shear stress

Simulation ResultsSimulation ResultsVerification of elevation between the observation data (IMAU Utrecht Univ.) and the simulation results at Muara Jawa; for the period of 30 June to 08 July 2003

Sebulu

Muara Badak

Tenggarong


Mahakam River Muara Jawa

Strait


The RMS error is 0.15 m

Muara Pegah

Makassar St

0 10 20 km

The location of transect

Open boundary


Simulation ResultsSimulation ResultsVerification of the current velocity component U (x direction, east (+) – west (-)) between the observation data (IMAU Utrecht Univ.) and the simulation results at Muara Jawa at depth of 4.0 m from the surface; for period of 30 June to 08 July 200ua a Ja a a dep o 0 o e su ace; o pe od o 30 Ju e o 08 Ju y 00

Sebulu

Muara Badak

Tenggarong



Strait

N Pulau NubiMuara BayurRMS error = 0.04 ms-1

Muara Pegah

Makassar St

0 10 20 km


Open boundary


Simulation ResultsSimulation ResultsVerification of suspended sediment concentration (SSC) between the observation data (IMAU Utrecht Univ.) and the simulation results at Muara Jawa at depth of 4.0 m from the surface for the period of 30 June to 08 July 2003.o e su ace o e pe od o 30 Ju e o 08 Ju y 003

Sebulu

Muara Badak

Tenggarong



Strait

N Pulau NubiMuara BayurRMS error = 33.11 mgL-1

Muara Pegah

Makassar St

0 10 20 km


Open boundary


Simulation ResultsThe spatial distribution of temperature on an along Muara Jawa to Muara Pegah outer transect during in neaptid dititide condition

0 29.00

Observation data on July 6, 2003(IMAU Utrecht Univ.)

-2

-4

Depth (m)

27.50

28.00

28.50 Temperature ( oC)

-6

454030201550 10 25 35horizontal distance (km)

27.00

Simulation results (neap condition)Sebulu

Tenggarong


Mahakam River

Muara Badak

Simulation results (neap condition)

28 00

28.50

29.00

Tempera

0

-2

h (m)

Muara Pegah

Mahakam River

kassar Strait


Muara Jawa

27.00

27.50

28.00 ature ( oC)

-6

-4

Depth

4030200 10

(b) Simulated

Open boundary

Muara Pegah

Makass

0 10 20 km


horizontal distance (km)

4030200 10

Simulation ResultsThe spatial distribution of salinity on an along Muara Jawa to Muara Pegah outer transect during in neaptid dititide condition

0

30.00


-2

-410.00

15.00

20.00

25.00 Salinity (PSU)Depth (m)


-6

454030201550 10 25 35

5.00


Sebulu

Tenggarong


Mahakam River

Muara Badak

Muara Jawa

Simulation results (neap condition)0

-2

(m) 20.00

25.00

30.00

Salini

Muara Pegah

Makassar Strait

N

0 10 20 km

Pulau NubiMuara Bayur

Muara Jawa

-6

-4

Depth

5.00

10.00

15.00

ity (PSU)

4030200 10

(b) Simulated

Open boundary

Maka0 10 20 km


4030200horizontal distance (km)

10

Simulation ResultsThe spatial distribution of σt (Sigma-t) on an along Muara Jawa to Muara Pegah outer transect during in neaptid dititide condition

0.02000Muara Jawa Muara Pegah


-2

-4 (a) Observed

Depth (m) Sigma-t

0.0125

0.0050


-6

( )

0.00254030200


10

Sebulu

Tenggarong


Muara Badak

Simulation results (neap condition)0

-2

(m) Sig

0.0200

0.0125

Mahakam River

ssar Strait


Muara Jawa

-6

-4

Depth

4030200 10

gma-t

0.0050

0.0025

(b) Simulated

Open boundary

Muara Pegah

Makassar

0 10 20 km



10

Simulation ResultsThe spatial distribution of suspended sediment concntration on an along Muara Jawa to Muara Pegah outert t d i i tid dititransect during in neap tide condition

0

-2

h (m)

Suspended Sedimen50

60

70

80

90

100Muara Jawa Muara Pegah


(a) Observation data(IMAU Utrecht Univ.)

-6

-4

Depth

nt Consentration (mg/l)0

10

20

30

40

50


10

(a) Observed

0 S100

-2

-4Depth (m)

Suspended Sediment Consentrat20

30

40

50

60

70

80

90

(b) Si l t d ( d )

Sebulu

TenggarongMuara Kaeli

Muara Badak

-64030200


10

tion (mg/l)0

10

20(b) Simulated (neap cond.)


Mahakam River

it

N Pulau Nubi

Muara Jawa

Muara Pegah

Makassar Strait

0 10 20 km

Pulau NubiMuara Bayur

Open boundary

M


Profile of cohesive sediment transport during neap tide conditionSimulation Results

Profile of cohesive sediment transport during neap tide condition

Sebulu

Tenggarong


Mahakam River

Muara Badak


ar Strait


Muara Jawa

Muara Pegah

Makassar

0 10 20 km


Open boundary

Simulation ResultsFlood condition Ebb condition

Simulation Results= 0.001 - 0.01378 g/m2/sec = 0.001 - 0.01378 g/m2/sec

/ 2/= 0.0001 - 0.001 g/m2/sec

= 0.0 - 0.0001 g/m2/sec

= 0.0001 - 0.001 g/m2/sec

= 0.0 - 0.0001 g/m2/sec

ＮＮ

0 10 20 km 0 10 20 km

The horizontal transport in neap tide condition

Simulation ResultsSimulation ResultsAverage condition

= 0.001 - 0.01378 g/m2/sec

= 0 0001 - 0 001 g/m2/sec

Average Condition

= 0.0001 - 0.001 g/m2/sec

= 0.0 - 0.0001 g/m2/sec

Ｎ

0 10 20 km

The horizontal transport in neap tide condition

ConclusionsConclusions During the flood tidal condition, the tidal current advected the higher salinity water into the estuary, resulting in a relatively large along estuary salinity gradient inside the estuarysalinity gradient inside the estuary.During the ebb tidal condition, the combined gravitational and tidal flows moved the low salinity water seaward from the upstream, leading to a rapid d f li i h h f hdecrease of salinity near the mouth of the estuary.Suspended sediment, transported to the delta from the upland, may be carried upstream when it settles into the lower layer, finally being deposited p y , y g pat the tip of the salt wedge.The tip of the salt wedge is located in the main river channel between 30 and 35 km from Muara Jawaand 35 km from Muara Jawa.The sediment from Mahakam river are mainly transported toward Muara Jawa and Muara Pegah rather than Muara Berau and Muara Bayur.

General ConclusionsGeneral ConclusionsThe tides in the Mahakam estuary are influenced by the complex delta f i b h i di h h h id lformation, bottom topography, river discharge when the tidal waves propagate from offshore area into the shallow estuary.The currents in the Mahakam delta waters are mostly affected by tides and y yriver flow. During the flood tide the current flows to the delta waters, and vice versa in the ebb tide.Sediment from the Mahakam river is transported downstream and becauseSediment from the Mahakam river is transported downstream, and because of settlement they reach in the lower layer and are transported back to the upstream by the flow in the lower layer to the convergence point.The delta is not developed eastward but is mainly developed northward and southward from the results of numerical experiment. Such information is very important for the integrated coastal area management in the Mahakam y p g gestuary.

Thank you very much for your kind attention

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