Intensity of Disasters Increasing

KOMPAS/HERU SRI KUMORO

Heavy equipment is used to help clear landslide debris at Pesona Kalisari housing complex, Kalisari village, Pasar Rebo, East Jakarta, on Tuesday, Nov. 27. Landslides occurred after heavy rains in the area on Monday.

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JAKARTA, KOMPAS — The intensity of hydrometeorological disasters is rising as the monsoon season sets in, triggering atmospheric instability in Indonesia. Consequently, floods, landslides and tornados hit regions across the country, especially in Java, early this week.

Heavy rain over the past week in Southeast Aceh led to flooding in eight villages on Monday, Nov. 26, at around 8:30 p.m. Mud and wooden debris flowed freely from the hilltop and into local homes. Consequently, six houses were heavily damaged and another 27 were inundated by mud.

“One house was carried away. We are still making a list of affected residents. All of them have now taken refuge at their relatives’ homes,” Aceh Disaster Management Agency (BPBD) head Teuku Ahmad Dadek said on Tuesday, Nov 27.

The flash flood also cut off the only bridge that connected several villages in Leuser district. These villages are now effectively isolated. Several village roads in Leuser also collapsed.

Flash floods also hit Bubulan and Gondang districts in Bojonegoro regency, East Java, on Sunday, Nov. 25. Some 54 households are now isolated.

National Disaster Mitigation Agency (BNPB) spokesman Sutopo Purwo Nugroho said in Jakarta that flooding also occurred in Ngoro district, Mojokerto regency, East Java, on Sunday.

In West Java, more than 100 homes were inundated in Cibadak subdistrict, Astanaanyar district, Bandung, Central Java, on Monday. Heavy rains led to the Citepus River rising 1.5 meters and bursting its banks. Stretches of Jl. Pagarsih became impassable, leading to traffic jams.

Floods also hit Cilegon in Banten, amid heavy rainfall, while water reservoirs were still under construction. Fifteen homes in Sukmajaya subdistrict, Jombang district, were inundated by 20 centimeters of water for 1.5 hours on Monday.

“The flood was triggered by overflowing of the Tumpang River that flows through several districts in Cilegon, including Cibeber and Cilegon,” the Sukmajaya subdistrict head said.

Moreover, heavy rain and strong winds also brought down trees in Cilegon. Tornados hit Serut village, Panti district, Jember regency, East Java, causing one fatality. Tornados in Masamba district, North Luwu regency, South Sulawesi, damaged seven homes.

Rainclouds increasing

The high intensity of hydrometeorological disasters followed the early warning given by deputy head of meteorology Mulyono R Prabowo of the Meteorology, Climatology and Geophysics Agency (BMKG). He said that a closed wind circulation had formed over the Java Sea, leading to the formation of wind convergence zones above Java, Bali, West Nusa Tenggara (NTB) and East Nusa Tenggara (NTT). Such weather conditions led to heavy rainfall in these areas.

Meanwhile, the inflow of a wet air mass from the Indian Ocean also contributed to the development of rainclouds in southern Sumatra, Java, Bali, Nusa Tenggara, South Kalimantan, South Sulawesi, Southeast Sulawesi and Maluku. This could lead to thunderstorms especially between Java and NTT until Nov. 30.

Data and information section head Zakaria Ahmad of BMKG’s Blang BIntang meteorology station in Aceh said the province would see the peak of the rainy season in November and December. In this period, flash floods and landslides may occur due to extreme rainfall.

Monsoon transition

BMKG’s head of air quality and climate information production subdivision, Siswanto, said that Indonesia was experiencing a transitional period from the Australian monsoon to the Asian monsoon that carried more water vapor mass due to evaporation on the South China Sea, the western Pacific Ocean and the Indian Ocean.

“Due to this shift in monsoon circulation systems, many wind convergence zones and instances of local air turbulence may appear, triggering atmospheric instability. This may lead to the creation of tall clouds that can trigger extreme rainfall,” Siswanto said.

BMKG monitoring shows that 60.7 percent of Indonesia has entered the rainy season. Regions that will see extremely high rainfall of more than 300 millimeters in 10 days include Pidie Jaya, Nias Islands, Riau, Bengkulu, Banyuasin, Pontianak, Sintang, Kapuas Hulu, West Kotawaringin, Murung Raya, Nunukan, Sorong, Nabire and Pegunungan Bintang. Regions that will see high rainfall of 90-300 millimeters in 10 days include Sumatra’s southern coast, most of West Java and Central Java.

Regions prone to floods due to forecast heavy rainfall include most of Sumatra, Banten, most of West Java, parts of Central Java, parts of Kalimantan, West Sulawesi, Central Sulawesi and small parts of Papua.

(AIK/AIN/BAY/RTG)