The weather patterns across the country are showing contrasting conditions. Some regions are seeing an increase in the intensity of rainfall that has caused a hydro-meteorological disaster, but other areas are witnessing continued drought.
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JAKARTA, KOMPAS — The weather patterns across the country are showing contrasting conditions. Some regions are seeing an increase in the intensity of rainfall that has caused a hydro-meteorological disaster, but other areas are witnessing continued drought.
Monitoring data on the transition from the dry to the rainy season shows that 39.3 percent of the country continues to experience drought, which is afflicting the majority of Lampung, most parts of Java, Bali, West Nusa Tenggara (NTB), East Nusa Tenggara (NTT) and Maluku, and small areas in Kalimantan, Sulawesi and Papua.
"Rainfall has been above the normal level in some areas, but [other areas] are still experiencing extreme drought," Siswanto, the head of climate and air quality information at the Meteorology, Climatology and Geophysics Agency (BMKG), said on Wednesday (28/11/2018).
Several regions have recorded meteorological drought categorized as “extreme”, with no rainfall for more than 61 days. Eleven regions in East Java have not seen rain for 61 to 225 days. These regions are Sumberbulu, Kaliklatak, Krasak, Paiton, Kalor Koran, Pasewaran, Bajulmati, Liwung, Dander, Lumbang and Grati.
Eight regions in Bali – Pengotan, Toya Bungkah, Celukan Bawang, Kintamani, Sukadana, Tianyar, Tejakula, dan Sambirenteng – have not seen rain for 76 to 235 days. The areas in NTB that have not had any rain include Sape (91 days), Sape 2 (246 days) and Rensing/West Sakra (106 days). Seven regions in NTT have had no rains for 82 to 255 days: Melolo, Biudukfoho, Daieko, Kawangu, Temu/Kanatang, Rambangaru and Danga. Benungan Kelara in South Sulawesi has had no rain for 139 days and Okaba in Papua has had no rain for 133 days.
The areas experiencing prolonged drought without rain for 31 to 60 days are Besuki and Wringinanom in East Java, Tukad Mungga in Bali, and Saumlaki in Maluku.
El Niño effect
The weather in Indonesia, Siswanto said, would be affected by a weak El Niño phenomenon that would last from December 2018 to February 2019. “There is a small possibility that El Niño will increase in intensity," he said.
A weak El Niño has occurred nine times since 1950, most recently in 2014-2015. These weak El Niño formations have generally been of short duration, ranging from five to six months.
According to an analysis of weak El Niño events in the past, a decline in monthly rainfall ranging from 5 to 50 percent compared to previous years has been recorded up to November. This effect has been seen in southern Sumatra, Java, Bali, East and West Nusa Tenggara, Sulawesi, Maluku and parts of Papua. Meanwhile, central and northern Sumatra, western and southern Kalimantan, and North Sulawesi and West Papua are experiencing a positive anomaly of increased rainfall.
December is forecast to see anomalous rainfall patterns from El Niño similar to November. However, northern Sumatra, eastern Kalimantan and West Papua are expected to see a shift from positive to negative anomalies.
Landslide and flood risks
Meanwhile, landslides and floods have occurred in some areas that have seen extended periods of heavy rain. In Bogor, heavy rain on Wednesday caused cracks in along roads near the recent landslide in Riung Gunung, Tugu Selatan village, Jl. Raya Puncak, Cisarua, Bogor. Half of the roads in the area are unpassable.
"People and motorists heading to Cianjur or Bandung are encouraged to use alternative routes through Jonggol, Cariu, [and] Sukabumi," said Bogor Police traffic unit chief Adj. Com. Hasby Ristama.
Heavy rain in Purwakarta, West Java, caused a landslide on Tuesday night, when a 5-meter cliff collapsed in Salam Jaya village, Pondok Salam subdistrict. Four people were killed and five others were seriously injured in the incident.
The Center for Volcanology and Geological Disaster Hazards Mitigation’s (CVGHM) November map on potential ground movement shows that landslides occurred in 17 Purwakarta subdistricts with a medium to high level of risk. "People are expected to watch actively for landslide warning signs such as cracks in cliffs or hills," said Wahyu Wibisono, the head of the Purwakarta Fire and Disaster Control Agency.
The South Sumatra regional disaster management agency has mapped 10 flood-prone areas and seven landslide-prone areas in the province. Flood-prone areas are generally located in daerah aliran sungai (DAS), or watershed areas.
In Bandung, Environment and Forestry Minister Siti Nurbaya Bakar asked all parties to be aware of potential landslide hazards in the rainy season in 15 watershed areas. The vulnerable areas were located near several large rivers: the Asahan Toba, Moyo, Serayu, Limboto, Solo, Brantas, Musi, Siak, Kapuas, Saddang, Jeneberang, Way Sekampung, Cisadane, Ciliwung and the Citarum. Deforestation of upstream areas is believed to be the main cause.