Indonesia: Flooding across parts of West Sumatra Province, May 12

Flood-related disruptions are ongoing across parts of Agam and Tanah Datar districts, West Sumatra Province, as of May 12. Heavy rainfall has been ongoing in the region since May 11, triggering widespread flooding and cold lava flow from volcano-hit area. Authorities have reported at least 28 fatalities, with 84 housing units and 16 bridges affected by the floods across the region. The Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) has forecast further showers across the West Sumatra Province through at least May 14. The BMKG is maintaining an early warning for moderate-to-heavy rainfall, which may be accompanied by lightning and strong winds across much of South Sumatra Province May 12-14.

Further sustained heavy rainfall could trigger additional flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil. Power outages could occur throughout the affected area.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could also cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

The disruptive weather may cause delays and cancellations at regional airports. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. Repair or reconstruction efforts may result in residual disruptions if there is severe damage to infrastructure.

Flooding could heighten the threat of disease outbreaks. Backflow from drains mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become a breeding ground for mosquitoes and bacteria, increasing the incidence of insect- and water-borne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.