The state water resources department has issued a flood alert for north Bihar districts bordering Nepal.
With heavy rainfall in the catchment areas in neighbouring Nepal, water levels of these rivers have been rising for the last 24 hours.
"The Gandak river is near the danger mark at some points in West Champaran district and Kosi is also in spate in Supaul district. Bagmati is showing rise in its water level in Sheohar district. Similarly, water level of Kosi and its tributaries is on rise in Shaharsa and Khagaria districts," an official of the department said.
The rivers have flooded more than 150 villages in Supaul, West Champaran and East Champaran, forcing people to abandon their homes. The river system is threatening hundreds of villages in over half a dozen districts, officials said.
Water level of the Ganga is rising in Patna and other places in Bihar.
Bihar Water Resources Development Minister Lalan Singh said preparations have been made to tackle the flood situation. "There is no need to panic. The state government is alert. All embankments are safe," he said.
Singh said the eastern Kosi embankment, which had breached in 2008, was safe.
In 2008, more than three million people were rendered homeless in Bihar when the Kosi river breached its banks upstream in Nepal and changed course.
According to Bihar Disaster Management Minister Chandrashekhar, the department has put its rescue and relief teams on a standby in flood-prone districts of the Koshi belt.
Official sources said engineers of the water resource department have been directed to keep a vigil on the vulnerable embankments.
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