Indonesia: Casualties and damage reported due to flooding and landslides across parts of North Sumatra Province as of Nov. 25

Response operations are ongoing following flooding and landslides across parts of North Sumatra Province as of Nov. 25. Heavy rainfall Nov. 22-24 triggered flash flooding and several landslides in hilly areas of the region. At least 16 people have been killed, dozens injured, and several others are missing across affected parts of the province. Several homes have been damaged by landslides or submerged by flooding. Protracted disruptions are likely in affected areas over the coming days as response and recovery operations continue.

Authorities have confirmed at least six fatalities, nine people injured, and four others missing after a landslide struck three buildings in Semangat Gunung village in Karo Regency late Nov. 24. At least four people were killed, nine injured, and two others are missing following flash flooding near the Martelu village in Deli Serdang Regency late Nov. 23. Response operations are ongoing in Harang Julu village in Padang Lawas Regency after a landslide struck several homes Nov. 23; at least four people are dead and several others missing. Flash flooding early Nov. 23 killed at least two people and damaged several homes across three villages in South Tapanuli Regency.

The Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) has forecast further rainfall of varying intensity across the region over the coming days. As of Nov. 25, an early warning for heavy rainfall accompanied by lightning and strong winds is in place across much of North Sumatra.

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 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.