Coastal Cities Facing Threat of Inundation

Name: Coastal Cities Facing Threat of Inundation
Uploaded: 2021-08-20T04:46:16Z
Duration: 20 min 32 s
Description: Overall, out of the 21 cities, there will be about 118,000 hectares of inundated areas, affecting 8.6 million people. The total economic losses are estimated at Rp 1.576 quadrillion.

Overall, out of the 21 cities, there will be about 118,000 hectares of inundated areas, affecting 8.6 million people. The total economic losses are estimated at Rp 1.576 quadrillion.

kompas team

· 6 minutes read

A total of 199 coastal regencies/cities in Indonesia are at great risk of experiencing annual tidal flooding by 2050, with around 118,000 hectares prone to seawater inundation, 8.6 million people likely to be effected and losses estimated at Rp 1.576 quadrillion.

Kompas has looked into the potential impact of rising sea level in 21 provincial capitals based on sea level rise simulation data from non-profit research institute Climate Central by combining spatial analysis, demographic and economic data, and local government policies.

From that analysis, the vulnerability index of each region was obtained. Using the Climate Central simulation, Kompas identified 199 out of 514 regencies/cities in Indonesia, including 21 provincial capitals, as facing exposure to annual high-tide flooding that would cause more than 2 percent of their areas to be submerged. Some of these areas are below sea level.

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The global sea level has been rising for the last 100 years with the impact expected to get worse in 2050. Overall, out of the 21 cities, there will be about 118,000 hectares of inundated areas, affecting 8.6 million people. The total economic losses are estimated at Rp 1.576 quadrillion.

Climate Central’s simulation uses the coastal digital elevation model (CoastalDEM) with varying accuracy in different regions.

The simulation uses a climate scenario with the assumption that the world commits to intensive greenhouse emission reduction, referred to by the Intergovernmental Panel on Climate Change (IPCC) as the representative concentration pathway (RCP) 2.6.

In addition to the RCP 2.6, Climate Central also adopts sea level rise projections from a study by United States researcher and climatologist Robert E. Kopp and his colleagues (2014). The Kopp projection is one of the most cited studies of sea level rise, including by the IPCC in its report.

Kopp projects that the global mean sea level could increase by 18-33 cm by 2050 and 29-82 cm by 2100. This means that, in the worst-case scenario, the sea level could reach 82 cm in coastal areas.

The simulated inland water elevation by Climate Central does not incorporate potential defense infrastructure, such as seawalls or levees. The estimated extent of the annual tidal flooding takes into account the effects of extreme weather and sea level rise, the latter being exacerbated by land subsidence in a number of areas.

Vulnerability index

The vulnerability index is determined by four parameters, namely the extent of area below sea level and its exposure to inundation by tidal flooding by 2050, the number of affected people, economic loss and local government risk reduction measures.

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The estimated submerged area is calculated by overlaying a flood map onto an administrative boundaries and settlement map from the Geospatial Information Agency (BIG). The number of people to be affected is based on the 2015 population raster data provided by the Global Human Settlement Layer (GHSL).

To estimate the value of economic losses, the calculation uses data on Gross Regional Domestic Product (GRDP) per capita and the number of affected people. The readiness of local governments is measured by how they prepare the risk mitigation measures over the impact of rising sea level.

The combined score of the four parameters is used to determine the level of vulnerability of 21 provincial capital cities in coastal areas.

The four parameters each give a vulnerability score ranging from 1 to 3. A score of 3 refers to a condition that has the most potential of contributing to the vulnerability of a city to tidal flooding. The combined score of the four parameters is used to determine the level of vulnerability of 21 provincial capital cities in coastal areas.

As a result, seven cities are categorized as being at a high level of vulnerability, nine cities at a medium level and five cities at a low level. The higher the estimated floodwater level in more extensive land, the more vulnerable the area is, which will also affect more people. This leads to more severe economic losses. Unprepared local governments over risk mitigation strategies are expected to suffer more.

Heightened severity

Banjarmasin is the city with the highest vulnerability in Indonesia. The area of tidal flooding in Banjarmasin is estimated to span 85.5 percent of the territory. The large portion of the inundated area, which is 86.6 percent, is settlement area.

It is estimated that 543,998 people or 83.6 percent will be displaced, with potential economic losses reaching up to Rp 24.8 trillion. Although Jakarta has committed to a number of mitigation measures to address the rising sea level, the city remains in the category of high vulnerability. Almost half the area is predicted to be undermined by tidal flooding by 2050.

That area is home to about 4.5 million people (46 percent of the population), while the economic losses are estimated at Rp 1.186 quadrillion, which is the highest among the other low-lying coastal cities.

The big cities in Indonesia categorized as being moderately vulnerable include Surabaya, Denpasar, Mataram, Semarang and Medan, with the estimated affected area constituting 17 to 37 percent. The majority of them have begun mitigation efforts even though it is still in the stage of the development process.

Mandalika is expected to attract more tourists now that an international MotoGP circuit is being constructed.

In addition to the provincial capitals, the special economic zone (SEZ) Mandalika in West Nusa Tenggara, is also exposed to tidal flooding by 2050 with the estimated affected area covering 940.4 hectares, or 70 percent of the SEZ area. Mandalika is expected to attract more tourists now that an international MotoGP circuit is being constructed.

Some of the 21 low-lying coastal cities are facing more severe tidal flooding due to land subsidence. According to Heri Andreas, a geodesy expert at the Bandung Institute of Technology (ITB), a number of big cities on the northern coast of Java that are built on alluvial soil or sediments, such as Jakarta and Semarang, are experiencing massive land subsidence of more than 10 cm per year.

This is due to the nature of the alluvial soil which continues to experience compaction because of on-ground loads and groundwater extraction. Land subsidence makes settlement areas more prone to tidal flooding.

Awareness

Rukuh Setiadi, an expert of spatial urban planning at Diponegoro University, said local governments and residents were not yet aware of the rising sea level threat in their area. The gradual nature of the rise makes the the threat unperceivable by the community as a lurking danger.

According to Parid Ridwanuddin, a deputy campaigner for public awareness with the People\'s Coalition for Fisheries Justice (Kiara), local governments need to research the potential impact of rising sea levels for the next 10 to 20 years. (PUT/SPW/XNA/HLN/OKA/DIT/ESA/JOL/NDU/RAM)

(This article was translated by Musthofid).

Editor:

naranasrullah

mandalika kompascetak Coastal Cities Climate Central simulation CoastalDEM Gross Regional Domestic Product GRDP Rukuh Setiadi