Floods in Jabodetabek are an Inevitability

Flood disasters in the Greater Jakarta area are an inevitability. The high population density and the low absorption capacity of the environment for overflowing water make the risk of flooding relatively very high in the Jakarta Province and its surrounding areas. The lack of green open spaces (RTH) makes the Greater Jakarta area perpetually vulnerable to becoming a flood-prone region every year.

Based on data from the National Disaster Management Agency (BNPB), in 2024, the number of flood events in Greater Jakarta reached at least 33 incidents. These floods submerged approximately 12,700 housing units, affecting around 50,800 residents living in the disaster-affected areas. About 1,000 of them were forced to evacuate due to the inundation caused by the floods.

The disaster will continue to escalate in line with the increasing intensity of rainfall. For instance, in 2021, the number of flood events across Greater Jakarta reached 99 incidents. The disaster claimed 16 lives, left 1 person missing, injured 269 others, and affected approximately 566,000 people. It even forced around 54,200 people to temporarily evacuate.

In 2021, the flood disaster submerged approximately 84,000 housing units across Greater Jakarta, causing severe damage to at least 60 units. The high intensity of disasters in 2021 was closely linked to the prolonged La Nina phenomenon during the 2021-2022 period, which resulted in a longer rainy season than usual.

In 2022, the La Nina phenomenon persisted and reached its peak phase during the period of August to November. This resulted in a high intensity of flood occurrences, with as many as 84 incidents across the Greater Jakarta area. Furthermore, the 2022 floods had an even broader impact, affecting up to 223,000 people and inundating 45,000 housing units.

Entering the period of 2023-2024, rainfall tends to decrease due to the presence of the El Niño phenomenon. This has also influenced the intensity of flood disasters, which have tended to recede in the Jabodetabek area during 2023-2024. In 2023, the number of flood incidents decreased from the previous year to 55 events. The extent of the impact also diminished, affecting approximately 71 thousand people and resulting in "only" 2 fatalities. In 2024, the frequency of floods further decreased to 33 events, with one fatality recorded.

From the data presented, it is evident that floods will consistently affect certain areas of Jabodetabek at any time. Every year, floods will occur with varying intensities and impacts. However, reflecting on the data from 2021-2024, flood disasters will invariably impact at least 50,000 people annually and result in loss of life.

Whether it is rainfall influenced by the El Nino phenomenon which tends to be dry or La Nina which tends to be wet, it will still cause flooding in the Jabodetabek area. However, relatively low rainfall generally results in fewer flood disasters.

In addition to rainfall, the factor that causes flooding in the Jabodetabek area is the minimal area of green open space. There is not a single area in Jabodetabek whose green open space area is in accordance with the regulations set by the government, which is 30 percent of the total area.

From a number of data collected from the National Waste Management Information System, Ministry of Environment and Forestry (SISPN KLHK) and from other sources, it shows that the area of green open space in Jabodetabek is on average no more than 9 percent of the area of each region.

The area with a relatively high green open space area in Jabodetabek is South Tangerang City with a percentage reaching 8.5 percent. Next, followed by Bekasi City with a green open space area of 7.68 percent; Jakarta Province 6.04 percent; and Bekasi Regency at 4.32 percent. For other areas such as Bogor City, Bogor Regency, Depok City, Tangerang City, and Tangerang Regency, the average green open space area is less than one percent, except for Bogor City which has a green open space area of around 2.6 percent.

With the minimal area of green open space, all environmental risks, especially flooding, are very high in Jabodetabek. Even low-intensity rain will risk triggering waterlogging on several roads. Moreover, high rainfall that lasts for a long time and evenly spreads from upstream to downstream. Certainly, flooding will be an event that will hit some areas of Jabodetabek.

In fact, specifically in the Jakarta Province, the flooding incident was not only due to high rainfall, but also triggered by environmental management that had relatively difficulty absorbing water runoff. According to BRIN's study, the condition of the land in Jakarta can no longer absorb water so that local rain that occurs in Jakarta makes the land and streets of Jakarta easily flooded. This is in line with the Walhi report which shows that around 52 percent of flooding incidents in Jakarta are not due to water runoff from upstream areas in the surrounding Bogor area.

The difficulty of water absorption in the Jakarta area is partly due to the high increase in the proportion of built-up land so that almost all land is covered by materials, cement, and buildings. More than 95 percent of land in Jakarta has changed its form to built-up land. This triggers land subsidence due to the heavy burden of infrastructure and the extraction of large amounts of groundwater, thus accelerating the rate of land subsidence.

Ironically, the area of green open space in Jakarta is only about 6 percent so that the absorption capacity of the soil is very minimal. As a result, puddles and floods will be inevitable when it rains.

The phenomenon is likely similar to other Jabodetabek areas that have massive infrastructure development. For example, in the Bekasi area which is densely populated for industrial development and also residential areas. This area is also very vulnerable to flooding every year. In fact, from every flood that occurs in the Jabodetabek area, a large proportion of the impact occurs in the Bekasi area, both Bekasi City and Bekasi Regency.

For example, in 2021, when rainfall was relatively very high, the area affected by flooding in Jabodetabek, around 69 percent of which was centered in the Bekasi area. Of the 566 thousand people affected, around 390 thousand were in the Bekasi area. Likewise, with the number of houses submerged in floods, the proportion of inundation in Bekasi reached 77 percent of all Jabodetabek. This of course caused the fatalities in Bekasi to be very high, namely 10 people or around 62 percent of all fatalities in Jabodetabek.

Uniquely, the high impact of flood damage in 2021, the frequency of flooding in Bekasi was only 17 events or only contributed less than 18 percent throughout Jabodetabek. This indicates that the environmental use in Bekasi is relatively minimal in water absorption. As a result, the flood disaster that hit caused the worst scale among other areas in Jabodetabek. So, the major flood incident like now in Bekasi is actually no different from the history that has been recorded so far. Bekasi is one of the centers of major flood events in Jabodetabek.

Flood mitigation efforts in Jabodetabek require a number of comprehensive steps from upstream to downstream. One thing that needs to be done immediately in the Jabodetabek urban area is to fulfill the RTH requirements required by regulations.

In Law No. 30/2007 on Spatial Planning, it is stated that the proportion of green open space in the city area is at least 30 percent of the city area. The proportion of public green open space in the city area is at least 20 percent of the city area.

The regulation specifically mandates the need for the provision and utilization of green open spaces, the proportion of which is set at least 30 percent of the city area. Where this green open space is filled with plants, both those that grow naturally and those that are intentionally planted.

The next regulation that regulates green open space is the Regulation of the Minister of Agrarian Affairs and Spatial Planning/Head of the National Land Agency Number 14 of 2022 concerning the Provision and Utilization of Green Open Space. The regulation mandates that public green open space is at least 20 percent and private green open space is at least 10 percent of the city area.

The regulation also mentions the provision and utilization of green open space by considering several functional aspects. For example, related to ecological functions, water absorption, economy, socio-culture, aesthetics, and disaster management.

Specifically related to flooding, RTH is intended to have a function to control flooding as well as a water catchment area and also a provider of groundwater recharge. With optimal functioning, it is hoped that RTH can play a role in reducing the risk of disasters, especially related to flooding. In addition, it becomes a space for disaster evacuation and post-disaster recovery.

With the large function of green open space for disaster mitigation efforts, it is only natural that local governments make maximum efforts to increase the proportion of green open space in their respective regions. By being more concerned about providing space for water to seep into the ground, it is hoped that there will not be many negative impacts on water that overflows due to rain. The environment will continue to maintain its natural balance as long as humans care about maintaining its ecosystem. (LITBANG KOMPAS)