Massive Landslide in Arunachal Pradesh Blocks Siji River, Triggers Flood Alert

A massive landslide triggered by relentless monsoon rainfall has struck Lower Siang district in Arunachal Pradesh, blocking the flow of the Siji River (Gai Nadi) and creating a temporary natural dam. Authorities have issued flood alerts for downstream areas, warning that if the debris barrier suddenly gives way, it could trigger flash floods affecting villages in both Arunachal Pradesh and neighbouring Assam.

The landslide occurred near Siji Block Point, where a large section of a hillside collapsed into the river. Dramatic videos circulating online show rocks, mud, and trees crashing into the valley, completely obstructing the river's natural course. Officials are closely monitoring the site as water continues to accumulate behind the debris, increasing pressure on the temporary dam.

The disaster is part of a broader monsoon emergency across Arunachal Pradesh. Heavy rainfall has caused widespread flooding and landslides in at least 12 districts, damaging roads, bridges, and homes while disrupting transport and communication networks. Search and rescue operations are underway, with state disaster response teams and the Indian Air Force assisting affected communities. Authorities have also reported casualties and several missing persons as rescue efforts continue.

Experts warn that natural dams formed by landslides are highly unstable. If the accumulated water breaches the blockage suddenly, it can unleash powerful flash floods downstream with little warning. Residents living near the Siji River have therefore been advised to stay alert, avoid riverbanks, and follow evacuation instructions issued by local authorities.

The incident highlights the growing impact of extreme weather in the Himalayan region. Environmental experts believe that intense rainfall, fragile mountain terrain, and climate change are increasing the frequency of such disasters. As rescue operations continue, the Arunachal landslide serves as another reminder of the urgent need for stronger disaster preparedness, resilient infrastructure, and early warning systems in India's vulnerable hill states.