Indonesia: Disruptions due to flooding ongoing in parts of North Sumatra Province as of Aug. 18

Event

Disruptions due to flooding are ongoing across parts of Medan City and other areas of North Sumatra Province as of Aug. 18. Heavy rainfall overnight Aug. 17-18 has caused the Deli and Babura rivers to overflow, affecting nearly 700 households across the Medan City area. Over 2,000 people have been affected and at least 30 are being housed in emergency accommodation due to their homes being flooded. Due to flooded roads, traffic congestion has also been reported across parts of the city Aug. 18. Over 100 homes have also been flooded in Dolok Batu Nanggar sub-district in Simalungun Regency of North Sumatra due to the overflowing Sikam River.

As of Aug. 18, the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) has issued yellow (the lowest on a three-tier scale) flood and heavy rainfall warnings across North Sumatra Province Aug. 18-20. Yellow thunderstorm warnings have been issued for the province Aug. 19-20. Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Hazardous Conditions
Further sustained heavy rainfall could trigger additional flooding in low-lying communities near rivers, streams, and creeks. Coastal flooding is also possible during high tides. 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 rainfall has saturated the soil. Power outages could occur throughout the affected area.

Transport
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. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.

Advice

Seek updated information on weather and related disruptions, including road conditions before driving or routing shipments through areas where severe weather is forecast. Plan accordingly for potential freight delivery delays if routing shipments by truck through the affected area. Do not attempt to drive through flooded areas. Charge battery-powered devices if prolonged electricity outages occur.

Resources

Indonesian Agency for Meteorology, Climatology, and Geophysics
Indonesian National Board for Disaster Management