Bangladesh, India: Monsoon rains trigger widespread flooding and disruptions over parts of northern and eastern Bangladesh and northeastern India as of July 4

Severe flooding continues to cause disruptions across parts of northern and eastern Bangladesh and northeastern India as of July 4. Heavy rainfall associated with the ongoing monsoon season has led to river levels rising to dangerous levels across much of the region, with the worst affected locations primarily in Sylhet Division in Bangladesh and Assam State in India. Further heavy rainfall is forecast across the region over the coming days and will likely exacerbate the flood situation, as well as hamper ongoing recovery efforts. Protracted disruptions will likely linger in flood-affected areas even after weather conditions improve and floodwaters recede due to damage to infrastructure, health concerns, and other flood impacts.

Swollen major river basins have been causing flooding in parts of Sylhet Division in Bangladesh since at least mid-June, with Sylhet and Sunamganj districts the worst affected areas. Around 1.8 million people have been affected in the region, of whom around 260,000 people have been displaced, and many others have been stranded by flooded roads. Authorities have reported at least 10 flood-related fatalities in the affected areas. Heavy rainfall has also caused landslides in the Cox's Bazaar area of Chattogram Division; authorities have reported at least 10 fatalities due to landslides since June 19, primarily amongst the population of refugee camps in the region. Around 50,000 people have been stranded due to flooding in Kurigram District in Rangpur Division. As of July 4, the Bangladesh Meteorological Department has forecast moderately heavy to very heavy rainfall over Chattogram, Sylhet, and Rangpur divisions July 4-6. Rainfall amounts are predicted to begin to decrease from July 7.

Authorities in Assam State have reported at least 56 fatalities due to flooding in recent weeks. More than 1.6 million people have been affected by flooding across 27 districts. Around 25,000 people have been displaced, and around 2,800 villages have been submerged by floodwaters. More than 500 people have been evacuated and around 72,000 others have been affected by flooding across Arunachal Pradesh State. At least nine flood-related fatalities have been reported across Manipur, Mizoram, and Nagaland states in recent days. As of July 4, the India Meteorological Department (IMD) has warned of further very heavy to extremely heavy rainfall across the region through at least July 8. The IMD has issued red rainfall warnings (the highest level on a three-tier scale) across Arunachal Pradesh, Assam, and Meghalaya states and orange rainfall warnings across Manipur, Mizoram, Nanagland and Tripura states July 4-5. Orange and yellow warnings are in place across much of the region July 6-8.

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 or a lack of 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. Disruptions to electricity and telecommunications services are likely where significant flooding, landslides, or strong winds impact utility networks.

Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation. Localized business disruptions may occur in low-lying areas.

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.