Dreaming of a Tsunami Barrier

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  • TEMPO.CO, Jakarta - On this day last year, Lingu (earthquake), Bomba Talu (tsunami), and liquefaction rocked Central Sulawesi, killing 4,845 people and displacing tens of thousands. Nine Palu journalists, members of the "Disaster Management Accountability" fellowship--a program held by Tempo Institute, International Media Support (Denmark), and AJI Palu, decided to tell the survivors' stories. They investigated projects suspected to be manifested with problems, as well as cover Palu's dream of having a tsunami wall. Here are their three coverages.

    A tsunami roared over the defenseless coast of Palu a year ago. Here is the plan to construct a tsunami barrier to prevent Palu from being easily overrun in the future.

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    Friday, March 11, 2011. An earthquake with a 9.0 magnitude rocked Tohoku, a coastal area in eastern Japan. It triggered a tsunami 10-40 meters high which rolled over the beaches about fifteen minutes later.

    Tohoku had made a lot of preparations to face a tsunami. They even had one of the strongest tsunami barriers in the world: a wave-breaking dyke 1,950 meters long whose foundations extend 67 meters deep into Kamaishi Bay, a tsunami gate, a reinforced-concrete wall along the coast, and evacuation buildings. However, the immense wave made it over the barrier. About 19,000 people died.

    On a different Friday, a year ago, an earthquake with a magnitude of 7.4 shook Palu and vicinity. Centered in Lende, Donggala Regency, about 80 kilometers northwest of the City of Palu, an earthquake triggered a tsunami wave 2-11 meters high.

    There were 1,365 victims in the City of Palu. This was more than in other coastal areas. The cause: the coast in Palu has not sunami protection in place.

    Then came the idea to build a tsunami barrier along the coast of Palu. The proposal initially came from Japan, through the Japan International Cooperation Agency (JICA). This institution founded by the Japanese government to help with construction in developing countries proposed the construction of a tsunami dyke.

    According to that proposal, the tsunami dyke would stretch along 120 meters of coastline. It would be three meters high. Spanning seven kilometers, from the coast of the Silae Sub-District in the west to the coast of the Talise Sub-District in the east, this barrier would look like a giant wall.

    About Rp800 billion to Rp1 trillion was needed. The Japanese Government was willing to lend funds for its construction, through a loan of Rp600 billion and $23.43 million or Rp328 billion from the ADB.

    This proposal immediately drew the attention of residents of Palu. Some of them said that they were not convinced about the claims of the efficacy of the tsunami barrier if it was built. Keep in mind that they knew about the failure of a similar tsunami barrier in Tohoku.

    Concerned about the Palu Koro Fault

    The Pasigala Center, a civil society coalition for the disaster in Palu, Sigi, Donggala, asked the National Development Planning Agency (BAPPENAS) to reconsider JICA’s plan to build that dyke. “That dyke plan needs to be reviewed. For one it is too expensive, and it has a large potential to be a technical failure,” said Pasigala Center Secretary-General Andika, on February 18, 2019.

    There is indeed a good chance that a tsunami barrier could fail in Palu Bay. The thing is, it would cut across the surface of the Palu Koro Fault. As a result, even before the arrival of a tsunami, the barrier could be destroyed by an earthquake, due to the down-lift or uplift of the land surface around the fault line.

    “This means that the tsunami dyke is not the way to reduce the risk of disaster, but to the contrary it raises the risks,” said Gegar S Praseyta, M.Sc, PhD, a tsunami expert from the Indonesian Association of Tsunami Experts, when speaking on a panel of experts for optimal coastal construction planning in Palu, as initiated by the Ministry of National Development Planning (Bappenas) in Palu on Thursday, August 8, 2019.

    Gegar explained that disaster mitigation which depends on physical means sometimes produces a false sense of security. This was seen in the tsunami tragedy in Japan. “At that time, many of the Japanese people living along the coast thought they were protected, and did not immediately evacuate when the tsunami warning sounded,” he said.

    However, this does not mean that physical construction is not needed. However, said Rahman Hidayat, another tsunami expert, the most important infrastructure to build is vertical evacuation along the coast.

    Dr. Abdul Muhari, S.Si, MT, head of the Disaster Mitigation Section at the Ministry of Fisheries and Maritime Affairs, agreed with building evacuation routes to move away from the coast. Accessibility in coastal regions in Indonesia, he said, is different than in Japan. “In Japan, the people do not always have activity taking place in coastal regions, unlike Indonesia, where the culture of coastal communities includes activity on the beaches,” he said.

    This could be seen with Bachtiar (67) and his only son, Anhar (38). The daily life of this fisherman in the Lere Sub-District, West Palu District, is connected with the beach and the sea. These two said that they disagree with the plan to build a barrier. They are worried that the dyke will put an end to their livelihood. “Hopefully the construction of this dyke will provide a location for our boats to dock,” said Akbar.

    Murni (63), who was selling salt at his simple wooden shack in front of Abadi Talise Field, and Usman (39), a salt farmer in Palu, have similar hopes.

    Nevertheless, at that time the government was unmoved by those concerns. On April 10, 2019, Governor of Central Sulawesi Longki Djanggola asked that the plan to build the tsunami dyke in Palu Bay not be obstructed for the good of the people, especially those who live near the coast. “Construction of the sea wall along Palu Bay has been planned, and the funds are ready, so let’s not have any more obstructions,” he said.

    He believes that the wall will be able to withstand a tsunami. The combination of mangrove trees and sea wall will likely increase the beauty of Palu Bay. “If this works, just imagine how beautiful Palu Bay will be,” he said.

    In the same vein, on April 25, 2019, Central Sulawesi Regional Secretary Hidayat Lamakarate said that the provincial government is targeting completion of a barrier along the coast of Palu Bay by 2020, even though opinions for and against this construction continue to be heard. The construction of this dyke, he said, also needs to done as soon as possible in order to prevent abrasion.

    The Palu Municipal Government even sent officials in the Regional Development Planning (Bappeda) Office and the City of Palu Zoning Office to take part in training in Japan for two weeks in May 2019, related to that dyke. Ibnu Mundzir, Head of Data and Information at the City of Palu Bappeda Office, who made that trip, explained that he was educated about the tsunami barrier. They also learned how Japan carries out post-disaster relief efforts, especially regarding zoning management, relocation, and infrastructure.

    On June 18, 2019, the City of Palu Public Works (PU) Office accompanied a team from Japan to survey the location of the sea wall and construction of the Palu IV Bridge, which replaces the Ponulele Bridge which was destroyed by the tsunami.

    From a Dyke to an Elevated Road

    Construction of that tsunami dyke appeared to be the way to go. However, on Thursday, August 8, 2019, in a meeting of a panel of experts initiated by the Ministry of National Development Planning (Bappenas) in Palu, there was further discussion about what construction approach to use in developing the coastal area around Palu Bay. At this third meeting of a panel of experts, JICA, through JICS expert in disaster prevention Naoto Tada, was no longer talking about a tsunami dyke, but proposed a new approach, an elevated road.

    As it turned out, the concept of a tsunami dyke failed to persevere after being tested by a panel of experts. One of the panel members, Dr. Ing. Ir. Widjo Kongko, M.Eng, a researcher from the Agency for the Assessment and Application of Technology (BPPT), said JICA changed the proposal after their first meeting on January 16. “I forget exactly (in which meeting). But there were three meetings,” he said. Whereas, he said, the elevated road idea was not mentioned in the previous planning. “In the planning signed by the Vice President, the term tsunami dyke was used,” he said.

    The same story was told by Iskandar Arsyad, Head of the Public Works Office of the City of Palu. The allure of the tsunami dyke, according to him, had faded during the second meeting of the panel, on June 26, 2019, in Jakarta.

    However, according to Widjo, from the very first time JICA proposed a tsunami dyke, he and some of his colleagues on the team of experts immediately objected. “With the typology of a medium-sized tsunami, mangrove trees and vegetation can reduce a tsunami wave by 20-30 percent,” he explained. “Vegetation is also good for the environment, is inexpensive, and brings added economic value for fishermen,” he added (See also: Under the Protection of the Mangrove).

    However, Dr. Abdul Muhari said that mangrove trees and coastal vegetation are only suitable for the coastal regions west of the Palu River, because the typology or the coast there is sloping and can be used for construction which retains sediment as a place for growing mangrove trees. “The same cannot be done on the coast of Palu Bay east of the Palu River, because of the steep coastal typology, which makes it unsuitable for planting mangroves,” he said.

    There is another problem on the eastern coast. If this stretch of land is to be used for planting coastal vegetation, the region must be cleared out at least 600 meters in from the shoreline. “It is no easy matter to relocate the people living in this area,” said Abdul Muhari.

    Widjo agreed. Based on a survey, he said, not all of the coastline provides enough space for planting vegetation. Consequently, according to Dr. Widjo, the concept being put forward by JICA then changed to an elevated road at a lower height. This elevated road would act as a ring road, zoning demarcation, limit of the green area, and a dyke in regions which have little or no space to plant vegetation.

    The plan was to make an elevated road about 6.5 meters above sea level and 4-5 meters above the surrounding land. However, after conducting an additional survey, the planned height of the elevated road was reduced 1.0-1.5 meters. This was done to reduce the depth of tsunami waters inside the City of Palu. In the end, the height of this roadway became less than 5 meters above sea level and 2.5-3.5 meters above the surface of the surrounding land.

    Later on this elevated road will have two segments. The first will be about 3.5 kilometers long, stretching from the coast west of the mouth of the Palu River, from the coastal area of the Silae Sub-District to the Lere Sub-District. The second segment will stretch 1.6 kilometers from the coast east of the mouth of the Palu River, from the coast in West Besusu to Talise.

    Mangroves Still Play a Role

    Along with the elevated road to be built, there will also be the construction of mangrove-based coastal protection. This will be done to withstand storm waves and coastal erosion. This coastal protection is to stretch 2.35 kilometers along the western coast of Palu Bay and 4.9 km along its eastern coast. Construction will cover the coastal area of the Silae Sub-District, Ulujadi District, to the coast of the Tondo Sub-District, Mantikulore District.

    The Emergency Assistance for Rehabilitation and Reconstruction (EARR): Project Administration Manual for Component I document issued by the Asian Development Bank (ADB) estimated the cost of this protective construction work at US$23.43 million. It includes a water resource infrastructure rehabilitation program. The document noted 2023 as the time limit to complete construction.

    In order to build this coastal protection, the ADB is ready to provide financial assistance. Vijay Padmanabhan, Director of the Urban Development and Water Division of the ADB in Southeast Asia, said in his press release on June 26, 2019, that the ADB has approved US$297.75 million of assistance for rehabilitation and reconstruction of public works and transportation infrastructure in Central Sulawesi. This figure includes the construction of coastal protection.

    Funding the tsunami barrier through debt-led Gegar S. Prasetya to warn the government to be cautious with each hard structure construction being planned. The thing is, this could happen not only in Palu, but in other areas which have a tsunami risk. With estimated financing of Rp800 billion to Rp1 trillion for each barrier constructed through loans, there will be a debt burden.

    However, it is not yet known if this elevated road concept will be applied in Palu. “The team of experts has given some proposals. If it is sounded out with other experts the results will not be much different,” he said.

    According to Widjo, there are two tasks to handle along the coast of Palu Bay, namely securing the coast from waves and flash flooding, and securing the coast from a tsunami. In his opinion, for the coastal area west of the mouth of the Palu River, securing the beach from a tsunami with a combination with vegetation is recommended, if there is sufficient room. For the coast east of the river, due to minimal space available for planting vegetation, there is the possibility of combining it with an elevated road.

    “To secure the coast from waves and flash flooding, I don’t know the details. Those running the project should be asked. Our concern has been that the design should be integrated so that people are not working separately resulting in duplicate work or budget overlap,” he said. Regarding the plan to construct an elevated road, said Widjo, their side is still proposing a design for further study.

    On a separate occasion, Ewin Sofian Winata, Head of the Water Resource Infrastructure Institutions Sub-Directorate at Bappenas, said that, based on the outcome of the meeting of the panel of experts from August 7-9, the team of experts agreed that there is a need to build a road to guarantee the flow of goods and services in Central Sulawesi. For that reason, according to Bappenas, the construction of coastal protection and an elevation road are a part of the planned loans from the ADB and JICA. Construction work is set to begin in 2020.

    For the vegetation approach, according to Ewin Sofian Winata, it has been agreed that coastal protection and an elevated road will be used in conjunction with vegetation, particularly in the western area of Palu Bay. “Because the topography there makes it possible,” said Ewin.

    Ewin said that the design of the coastal protection and elevated road has not been finalized, because it is going to be reintegrated by the Ministry of Public Works and Public Housing. The thing is, there are several points where these two types of work are adjacent. 

    However, it seems that the government is speeding up the work. Even though the design of the coastal protection and elevated road is not final, construction of the coastal protection has entered the auction stage. The ADB, on July 21, issued an invitation bid containing an announcement for the opening of bidding for one construction job for coastal protection, namely a water resource network implementation with a work package budget ceiling of Rp100 million of the total project package of Rp328 billion.

    In that invitation bid, the Sulawesi River Area Center III as the employer, opened online bidding/tender for ADB providing countries which meet the conditions. This auction uses a one-envelope open competitive offer procedure. The deadline for submitting offers ends on August 14, 2019, at 10 a.m. Central Indonesian Time.

    Bappenas verified that the construction of coastal protection using ADB loan funds has entered the bidding stage. The elevated road has been agreed upon by the experts according to a letter of the Ministry of National Development Planning (Bappenas) dated August 29, 2019.

    A letter signed by Abdul Malik Sadat Idris, Director of Waterworks and Irrigation at Bappenas, listed ten recommendations from national experts regarding tsunami dangers and five recommendations regarding the threat of earthquakes and land liquefaction.

    Construction of an elevated road was mentioned in the fourth recommendation. The panel of experts recommended building one as the primary logistics route in the Province of Central Sulawesi, to be used to control zoning in the red zone, and to reduce the energy of a tsunami.

    This elevated road concept was modeled on the recent disaster, when the incoming tsunami wave was 3-5 meters high over a four-minute period. In this way, the road’s design will match its new function to reduce a tsunami’s energy and to protect the coast from high waves.

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    Protected by the Mangrove

    ERNI took a fish from a thermos and place a line from a coconut leaf in the fish’s mouth. She then hung it up on some wood in a shack near her house. This 46-year-old woman then sat and waited for buyers, while watching the traffic passing the Trans Palu–Donggala Road.

    From behind her house, the blue sea and foamy waves could be seen between the lush mangrove trees. Roots resembling thorns poked out around the trees. These mangroves neatly lined hundreds of meters along the coast, right behind local residences.

    “It’s a good thing the mangroves are here. If not, maybe not only my kitchen would have been destroyed,” she said on Thursday, August 22, 2019, while pointing to her kitchen walls which were being renovated.

    Ermi’s home is just fifteen meters from the coast. The only thing separating them are a row of mangrove trees stretching from the coast to her backyard. “Praised be God, those whose homes were behind these trees were not damaged as badly as those whose homes are not obstructed by the mangroves,” Ermi continued.

    Ermi lives in Pangga Hamlet, which is located in the Kabonga Besar Sub-District, Banawa District, Donggala Regency, one of the areas affected by the tsunami on September 28, 2018.

    Asir, Chairman of Neighborhood Association (RT) 02/Block Association (RW) 01 in Pangga Hamlet, said that the tsunami damaged 36 houses in the hamlet.

    “Conditions were the worst in RT 01/RW 01, because no mangroves grow on the coast there. In RT 02, even though there was some damage, it was not as bad as in RT 01,” he said.

    In RT 01 the tsunami wave reached across the road and swept away some objects, such as motorcycles. Asir added that one person died, a child who was swept off the road by the tsunami, while returning home from a religious study meeting in a neighboring village.

    Pangga Hamlet is the first hamlet in the Kabonga Besar Sub-District from the direction of the City of Palu. It is about 25 km from the City of Palu.

    On Thursday, August 22, 2019, Rahmatriyadi, Head of the Kabonga Besar Sub-District, said that of the four RW in his sub-district, only one RW—including Pangga Hamlet—was damaged by the tsunami. This was because in that hamlet the mangrove trees were not thick and dense.

    The other three RW on the coast survived because of the thick and dense patch of mangrove trees. “They were only affected by the earthquake,” said Rahmatriyadi.

    Whereas, according to Widjo Kongko, a researcher at BPPT, the tsunami wave which hit the Kabonga Besar Sub-District was 3-5 meters high. However, he said, after the wave encountered the belt of mangroves 3 kilometers long and 50-75 meters wide, it shrunk to 1-1.5 meters.

    In the City of Palu, which has an unobstructed coastline, a wave this high is deadly.

    Dr. Bau Toknok, a researcher in Forest Resource Conservation at the Forestry Faculty of the Tadulako University (Untad), explained that in order to mitigate a tsunami, the density and thickness of the mangrove ecosystem needs to be noted. He said that there should be more than 10,000 mangrove trees per hectare.

    Yurianto, Chairman of the Gonenggati Jaya Forest Farming Community, who also runs a mangrove tourism area in the sub-district, said that thanks to those trees the tsunami wave only looked like high tide. “The floor of this shack was flooded, but thank God the water did not make it to the road,” he said.

    The Gonenggati Jaya Community has managed this mangrove tourism area since 2017, supported by the Banawa Lalundu Forest Management Unit (KPH). It covers about two hectares of the total ten hectares of the Kabonga mangrove forest. “The idea for it came in 2015,” he said.

    In this area, we can find a dense mangrove belt. The mangrove’s dense branches, which grow more than five meters high and deep roots, are a comfortable home for shrimp, crab, and coastal birds.

    Yuryanto said that six species of mangrove have been growing naturally for decades in the Gonenggatii Forest: rhizophora Apiculata, avicennia Lanata, nypa Fruticana, rhizophora Mucronata, rhizophora Stylosa and sonneratia Alba.

    The Gonenggati Jaya Community, said Yuryanto, developed the mangrove tourism area based on the idea to capitalize on the potential for nature tourism in the village, as well as an effort to improve the local economy. The most important thing, he said, is that this tourism area was built and is managed by a group consisting mostly of youths.

    Yuryanto said that the idea to create a Forest Farming Community came about when he saw that the mangrove forest in their area was becoming endangered. At that time many people were cutting down mangroves just to hunt for worms to use the wood for building things. However, the mangroves are important for fishermen as a place for fish, shrimp and crabs to spawn. “The mangrove forest used to be much larger than it is now,” he said.

    One effort being carried out by this group to stop the damage to the mangrove forest is to ban cutting down trees. To restore the ecosystem, they also plant mangrove seedlings on their own by using maturing seeds.

    Those seeds are initially grown as seedlings. After growing for about two months, the seedlings are planted in areas where the mangroves are damaged or bare. Yuryanto claims that the Forest Farming Community has planted thousands of seedlings along the Kabonga Besar coast.

    So that the mangrove forest benefits the residents, the Gonenggati Community initiated tourism education. They recruited fifteen residents from around the forest to work in this tourism area.

    The Forest Farming Community then improved the mangrove forest by building bamboo footbridges, so that visitors can reach inside the forest; building wooden cottages and decks for relaxing, with enticing views of Palu Bay; and recycling plastic drink bottles, painting them, and arranging them into displays for taking selfies. In this way, the Gonenggati Community has been able to attract many visitors, in addition to protecting the neighborhoods behind it from tsunami waves.

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