BMKG: Atmospheric Dynamics Trigger Flooding During Dry Season
The Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) has stated that atmospheric dynamics, such as the Equatorial Rossby wave phenomenon, alongside human interference, are triggering floods amidst the national dry season period.
Speaking at the ANTARA Heritage Centre in Jakarta on Thursday, the Head of BMKG, Teuku Faisal Fathani, noted that weather conditions during the transition towards the dry season are highly complex due to various daily variations. “There are also elements related to the Equatorial Rossby wave, Kelvin waves, the Madden-Julian Oscillation (MJO), and so on, which can cause daily variations,” he said.
Fathani explained that these indicators mean rainfall still has the potential to occur in several maritime and land regions of Indonesia, even though the climatology directorate has announced the commencement of this year’s dry season. As of the end of May, BMKG’s monitoring system recorded that only about 24 per cent of the total 699 Seasonal Zones (ZOM) across the country had officially entered the dry season, with the remainder expected to follow in June.
Furthermore, Fathani elaborated that the impact of reduced rainfall intensity influenced by the El Niño phenomenon does not affect all regions equally, but is generally concentrated south of the equator.
In addition to atmospheric dynamics, BMKG highlighted the significant role of local factors and human interference, such as the massive development of residential areas and the siltation of river structures in various regions. Such land-use changes and environmental degradation have created new vulnerabilities; according to him, moderate rainfall that previously caused no issues is now directly triggering flash floods and landslides.
This explanation aligns with reports from the National Disaster Management Agency (BNPB), which recorded several areas hit by floods and landslides due to high rainfall intensity in recent weeks. These events occurred while other parts of the country faced decreasing rainfall, leading to an increased risk of forest and land fires.
The BNPB Operations Control Centre (Pusdalops) reported, among other incidents, flooding in Manado, North Sulawesi, on Friday (28/5). Approximately 747 people were forced to evacuate to safer locations following floods that submerged residential areas. The flooding was triggered by overflowing rivers and drainage systems that were unable to contain the high intensity of the rainfall.