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Projections of tsunami inundation area coupled with impacts of sea level rise in Banda
Aceh, Indonesia
Tursina, Syamsidik, and Shigeru Kato
Citation: AIP Conference Proceedings 1892, 100003 (2017);
View online: https://doi.org/10.1063/1.5005735
View Table of Contents: http://aip.scitation.org/toc/apc/1892/1
Published by the American Institute of Physics
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Projections of Tsunami Inundation Area Coupled with
Impacts of Sea Level Rise in Banda Aceh, Indonesia
Tursina1, a), Syamsidik2, b) and Shigeru Kato3, c)
1, 2
Tsunami Computation and Visualization Laboratory, Tsunami and Disaster Mitigation Research Center
(TDMRC), Syiah Kuala University, Jl. Prof. Ibrahim Hasan, Gampong Pie, Banda Aceh, 23233, Indonesia
2
Civil Engineering Department, Syiah Kuala University, Jl. Syeh Abdurrauf, No. 7, Banda Aceh, 23111,
Indonesia
3
Department of Architecture and Civil Engineering, Toyohashi University of Technology, 1-1 Tempaku-Cho
441-8580, Aichi Prefecture, Japan
a)
Corresponding author: tursina@tdmrc.org
b)
syamsidik@tdmrc.org
c)
s-kato@ace.tut.ac.jp
Abstract. In a long term, sea level rise is anticipated to give devastating effects on Banda Aceh, as one of the coastal
cities in the northern tip of Sumatra. The growth of the population and buildings in the city has come to the stage where
the coastal area is vulnerable to any coastal hazard. Some public facilities and settlements have been constructed and
keep expanding in the future. According to TOPEX/POSEIDON satellite images, 7 mm/year the sea level has been
risen between 1992 and 2015 in this area. It is estimated that in the next 100 years, there will be 700 mm additional
sea level rise which will give a setback more over to a rather flat area around the coast. This research is aim at
investigating the influence of sea level rise toward the tsunami inundation on the land area particularly the impacts on
Banda Aceh city. Cornell Multigrid Coupled Tsunami Model (COMCOT) simulation numerically generated tsunami
propagation. Topography and bathymetry data were collected from GEBCO and updated with the available nautical
chart (DISHIDROS, JICA, and field measurements). Geological movement of the underwater fault was generated
using Piatanesi and Lorito of 9.15 Mw 2004 multi-fault scenario. The inundation area produced by COMCOT revealed
that the inundation area was expanded to several hundred meters from the shoreline. To investigate the impacts of
tsunami wave on Banda Aceh, the inundation area were digitized and analyzed with Quantum GIS spatial tools. The
Quantum GIS analyzed inundations area affected by the projected tsunami. It will give a new tsunami-prone coastal
area map induced by sea level rise in 100 years.
INTRODUCTION
Banda Aceh, the capital city of Aceh Province, is one of the coastal cities in the northern tip of Sumatra Island,
Indonesia. The growth of coastal communities in the city has come to the stage where the coastal area is vulnerable
to any coastal hazard. During the 2004 Indian Ocean Tsunami, Banda Aceh is one of the worst severely damaged
areas since the location of Banda Aceh is near to the earthquake epic-center (Sunda Megathrust). In addition, the
worst inundated area most probably due to the low-lying of topographic elevation of Banda Aceh itself.
In the last few years, the world gives more attention to the impact of global warming especially on Sea Level
Rise (SLR). It is estimated that the rising global temperature will also rise the sea level as well. In the long term,
SLR is expected to give significant adverse impacts coupled with coastal hazard on the low-lying region such as
retreat of the shoreline, wetland flooding, soil contamination of aquifer and agricultural. As at the present, the
preparedness regarding the sea level rise is rather decent which represented by researches and the study reports
from developed countries [1, 2, 3]. The regional sea level rise in Indonesia region over the period 1992-2015 was
7 mm/year [2]. It means that in 100 years later, the water surface of Indonesia’s seas (in this case Banda Aceh)
will be rising at about 700 mm from the present condition. Although the estimation is a small number, the lowlying coastal area such as Banda Aceh will be among the most vulnerable cities toward impacts of the sea level
rise.
After a mega earthquake on December 26, 2004, Banda Aceh was hit severely by a tsunami and since then,
the city has been stated as one of disaster-prone cities [4]. It means that Banda Aceh is vulnerable to coastal
Proceedings of the International Conference of Global Network for Innovative Technology and AWAM International Conference in Civil Engineering (IGNITE-AICCE’17)
AIP Conf. Proc. 1892, 100003-1–100003-8; https://doi.org/10.1063/1.5005735
Published by AIP Publishing. 978-0-7354-1574-4/$30.00
100003-1
hazards such as tsunami and sea level rise. In 2009, [5] conducted a similar research about re-mapping the 2004
tsunami inundation combined with probable sea level rise within the next 100 years. The result of this research
shows that the inundation paths of the tsunami with SLR 100 years propagate 0.5 to 1.8 kilometers farther inland
than tsunami event in 2004. Therefore, this research is aim at investigating the influence of sea level rise towards
tsunami inundation of a future tsunami event on the land area and the direct impacts on Banda Aceh.
THE STUDY AREA
Banda Aceh is selected as the study area in this research that was severely affected by the 2004 Indian Ocean
Tsunami [6]. It is located on the northern tip of Sumatra. Banda Aceh administrative area is approximately 61.36
km2 in area. Topography condition in Banda Aceh relatively flat with the highest elevation is not more than 8 m
AMSL (Above Mean Sea Level). There are three main rivers which flow across to the city namely Krueng Neng
River, Krueng Aceh River, and floodway Krueng Aceh. Floodway Krueng Aceh is the flood canal which divides
the river discharge from Krueng Aceh River into two outlets (river mouths). Besides, there are also many small
rivers and retention basins which also connect their outlets to Banda Aceh Coast. The city had massively damaged
by the waves after Indian Ocean Tsunami in 2004. Through the Abasiyah Foundation, the Japanese government
had built 85 tsunami poles as tsunami memorial. Among the tsunami memorial poles, 67 of them located in Banda
Aceh and contain the information about the coordinate and the tsunami wave height based on local witnesses and
watermarks [7]. The study area is shown in Fig 1.
FIGURE 1. Study Area with Tsunami Pole in Banda Aceh City
METHOD
This study utilized tsunami numerical hydrodynamic model called Cornell Multi-grid Coupled Tsunami
(COMCOT) to simulate tsunami propagation on the effect of sea level rise. The COMCOT model was also used
by [8] in proving the effect of tsunami waves that caused the Ujong Seudeun land separation from the Sumatra
mainland. In the tsunami numerical simulation, a fault model is required to generate the tsunami wave from the
source. This study used the multi-fault model by that proposed by Piatanesi and Lorito [9]. Previous researchers
also used the same fault model for their 2004 tsunami numerical model [10, 11]. The initial surface from seafloor
deformation from the multi-fault can be seen in Fig. 2. The topography and bathymetry data were collected from
General Bathymetric Chart of the Oceans (GEBCO) and updated with the available nautical chart (DISHIDROS,
JICA, and field measurements). The data were interpolated into 15.5 m x 15.5 m of grid size. A time step of 1.0 s
was used for tsunami simulation. In our simulations, sediment transport process on study area was not included.
The input parameter on each layer can be seen in Table 1 and simulation layers can be seen in Fig 3.
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Scenario 1 was simulated the existing 2004 tsunami event using multi-fault scenario. The tsunami wave height
that produced from COMCOT simulation was compared with the tsunami pole at the same position. As a
comparison for the reference to use the model, the simulation result and the available tsunami pole were compared
at the same position. By comparing the resuls, it shows whether the results are agreable to the tsunami pole data
or not. Based on that, the second scenario was simulated which involved the sea level rise (SLR) within 100 years
that applied into the Piatanesi and Lorito fault model. The sea level rise scenario was added by changing the
AMSL into raised sea level which is 0.7 m. This scenario resulted the existing elevation to be submerged within
0.7 m. The new bathymetric data also became 0.7 m deeper. Furthermore, this new topography and bathymetry
data became the input for simulation domain in 100 years SLR scenario.
FIGURE 2. Initial surface elevation
TABLE 1. Information on the setup of the five layer for COMCOT simulations
Layer
1
2
3
4
5
Longitude(qq)
Latitude (qq)
From 88.1 to
102.8
From 92.05
to 97.98
From 94.51
to 95.99
From 95.14
to 95.39
From 95.23
to 95.390
From 0.1 to
14.93
From 4.08 to
8.98
From 5.2708
to 6.695
From 5.415
to 5.69
From 5.502
to 5.628
Grid Size
(m)
(min)
Grid
Ratio
Coordinate
system
Type
SWE
1856
1
1
Spherical
Linear
928
0.5
2
Spherical
Linear
309.3
0.166667
3
Spherical
Linear
77.333
0.041667
4
Spherical
Linear
15.46667
0.008333
5
Spherical
Nonlinear
The NSWEs (Nonlinear Shallow Water Equation) in COMCOT are given by
߲ߟ ߲݄‫ݒ݄߲ ݑ‬
൅
൅
ൌ Ͳሺͳሻ
߲‫ݐ‬
߲‫ݔ‬
߲‫ݕ‬
߲‫ݑ‬
߲‫݊݃ ݑ‬ଶ
߲ߟ
߲‫ݑ‬
൅‫ݑ‬
൅‫ݒ‬
൅
‫ݑ‬ඥ‫ݑ‬ଶ ൅ ‫ ݒ‬ଶ ൌ െ݃ ሺʹሻ
߲‫ݔ‬
߲‫݄ ݕ‬ସൗଷ
߲‫ݔ‬
߲‫ݐ‬
߲‫ݒ‬
߲‫݊݃ ݒ‬ଶ
߲ߟ
߲‫ݒ‬
൅‫ݑ‬
൅‫ݒ‬
൅
‫ ݒ‬ඥ‫ݑ‬ଶ ൅ ‫ ݒ‬ଶ ൌ െ݃ ሺ͵ሻ
߲‫ݔ‬
߲‫݄ ݕ‬ସൗଷ
߲‫ݕ‬
߲‫ݐ‬
Where ߟ = surface elevation (m); h = the total water depth (m); u and v = the depth average velocities in the x
dan y directions, respectively (m/s); U = the water density (kg/m3); g = the gravitational acceleration (m/s2); n =
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the Manning’s coefficient for bottom roughness. We used a uniform value for the bottom roughness of land and
sea area with Manning’s coefficient n = 0.02.
FIGURE 3. Layer domain in COMCOT
RESULTS
The results of these simulations are reported below. This study result shows the impacts of the sea level rise
toward the tsunami on Banda Aceh area. The numerical result represented the comparison in visual maps and
graphic of tsunami propagation between the existing 2004 tsunami event and projected future tsunami in the next
100 years. Spatial analysis of the impact on future 100 years tsunami projection was also observed to give the
future tsunami-prone coastal area map induced by 100 years SLR in Banda Aceh territory.
Tsunami and Tsunami+SLR 100 Wave Run-up
The tsunami waves produced by 2004 Indian Ocean Tsunami [9] couple with a 100 years sea level rise had
been simulated. The tsunami that generated from the Indian Ocean propagated toward the Banda Aceh land area.
The addition of 0.7 m water level boost the tsunami waves compare to the 2004 condition. The waves went through
the low-lying area and the available channel and overtopped to the most populated area. As shown in Fig 4, the
first wave reached the land about the 34th minute after the earthquake. This value is relatively similar to the results
of the research about Estimated Time of Arrival (ETA) of the tsunami with ETA for Banda Aceh is 35 minutes
[4]. However, for the scenario of tsunami + SLR100, ETA becomes 3 minutes shorter, giving 32 minutes time to
evacuate (5.88 % faster). By increasing sea level, the tsunami wave came only 3 minutes faster on the wet area.
After reaching about 4 km inland from the coastline, the tsunami flow was forced to inundate from the river
channel because it cannot hold the water volume anymore. The change of the topography and bathymetry
including the river meandering position also contribute onto this anomaly.
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A1.
A2.
T= 34 min
B1.
B2.
T= 50 min
C1.
C2.
T= 90 min
n D2.
D1.
T= 126 min
FIGURE 4. The Comparison of The Existing Tsunami Wave Run-up (Left) and The Wave Run-up of
Tsunami+SLR100 (Right)
Several observation points were deployed to record the wave’s height and velocity. One of them represented
the comparison between the wave height of the 2004 Indian Ocean Tsunami scenario and the additional 100 years
sea level rise. In the first wave struck with 0.36 m height while the second wave followed with a higher wave,
1.50 m. The wave had massively destroyed the city as proven on December 26, 2004. Combining the 2004 tsunami
scenario with the increase of 0.7 sea level rise in 2004, it revealed that the SLR gave a significant impact on the
tsunami wave’s height. The comparison between the actual event (tsunami pole) and the 2004 model was
presented which gave a good agreement. In addition, the comparison between 2004 model and the 100 years SLR
projection model can be seen in Table 2.
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TABLE 2. The comparison data recorded and model simulation
Observation
Point
Distance
from the
shoreline
(km)
The height tsunami
wave recorded in
Tsunami Pole
(m)
1
2
3
4
5
2.7
3.5
3.5
3.8
3.2
3.4
3.2
2.45
1.4
3.4
Maximum tsunami wave height from
COMCOT simulation (m)
Tsunami+SLR100
Tsunami 2004
years
3.140
4.027
2.811
3.607
3.104
3.318
1.523
3.028
3.230
3.496
The Percent of
Amplification
(%)
128.251
128.336
106.908
198.831
108.235
A more detail visualization of the amplification caused by 100 years SLR in a time series format can be seen
in Fig. 5. The comparison is based on one of the available observation points (observation point 4).
FIGURE 5. Tsunami wave height (from Mean Sea Level) at Observation Point 4 (3.80 km from shoreline)
Tsunami and Tsunami+SLR 100 Years Maximum Inundation
The maximum tsunami wave height in Banda Aceh is shown in Fig. 6 and Fig. 7. In 2004 scenario, the tsunami
had inundated far inland reaching 3.65 km as describe in 2005 satellite image. The real recorded of 2004 tsunami
shows that 3.5 km distance from the shoreline had been passed by the wave run-up. The addition of the 0.7 m sea
level rise had amplified the wave run up from 2004 even 1.7 times in distance. Almost 6 km distance had passed
by 100 years after sea level rise. The tsunami wave height at the Baiturrahman Grand Mosque as the center of
Banda Aceh could reach about 3.230 m in 2004 tsunami event. Compared to the 2004, 100 year SLR will amplify
tsunami wave height about 8.24% in height or become 3.496 m at observation point 5.
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FIGURE 6. Maximum Inundation of Tsunami 2004
FIGURE 7. Maximum Inundation of Tsunami + SLR100
CONCLUSIONS
The COMCOT model was used to investigate the projection of tsunami inundation area coupled with the
impact of Sea Level Rise (SLR) in Banda Aceh. The numerical simulation results indicate the SLR 100 years later
will exacerbate the impact of the tsunami inundation limit extent of approximately 2.5 km inland. Although some
limitation of this research, such as the sediment transport process, the influence of land cover and land subsidence
that is not included, the authors believe that future tsunami-related SLR worsen the impacts of possible or future
tsunami in Banda Aceh. In addition, the SLR could amplify the inundation distance and resulted in faster arrival
of tsunami waves for about 3 minutes faster than without SLR. The accelarated 3 minutes of tsunami waves arrival
could mean alot for saving people and the region.
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ACKNOWLEDGMENTS
We are grateful to the Partnership Enhanced Engagement in Research (PEER) Cycle 5 funded by USAID and
the National Academy of Sciences (NAS) with the research title: ‘‘Incorporating Climate Change Induced Sea
Level Rise Information into Coastal Cities’ Preparedness towards Coastal Hazards’’ under Federal Award
Identification Number (FAIN): AID-OAA-A-11-00012 (sub-award Number 2000007546). Authors are
immensely grateful to BAPPEDA Banda Aceh for willingness to provide the detail topographical data. Also, we
are thank you to Musa Al‘ala, Teuku Muhammad Rasyif, Fachrurrazi, Sri Hartuti and all member of Coastal
Research Group (CRG) Unsyiah for their contribution in some part of this research.
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