Archive · 12 Sep 2026
Bihar Floods Highlight Need for Basin-Wide River Cooperation
Bihar is facing serious floods even though it received less rain than usual overall.
Some places had very heavy rain in short periods, while rivers also carried large amounts of water from upstream.
Several major rivers rose above their danger levels.
The high Ganga made it harder for the Gandak and Punpun to drain into it.
This caused water to back up into nearby areas.
Embankments can protect land, but they can also make flooding worse when they break.
Experts say Bihar needs better drainage, protected floodplains, restored wetlands and improved warnings.
States sharing the river basin also need to coordinate reservoir water releases.
Bihar received 27% below-normal rainfall from June 1 through the first week of September.
The Ganga, Gandak, Kosi, Budhi Gandak, Punpun and Ghaghra exceeded danger levels in different stretches.
High upstream flows and intense, localised rain contributed to flooding despite an overall rainfall deficit.
The Ganga’s unusually high level caused a backwater effect in the Gandak and Punpun rivers.
The state needs improved drainage, floodplain protection, wetlands restoration, early warnings and greater coordination over reservoir releases.
- Who
- Bihar and other riverine states sharing the basin are affected or involved.
- What
- Large parts of Bihar have flooded as several rivers rose above danger levels.
- When
- During the period from June 1 through the first week of September and the monsoon flood season.
- Where
- Across large parts of Bihar, including stretches of the Ganga, Gandak, Kosi, Budhi Gandak, Punpun and Ghaghra rivers.
- Why
- High upstream flows, localised heavy rainfall, the Ganga’s backwater effect and restricted drainage contributed to the flooding.
- Rainfall
- Bihar received 27% below-normal rainfall between June 1 and the first week of September.
- Rivers above danger levels
- The Ganga, Gandak, Kosi, Budhi Gandak, Punpun and Ghaghra rose above danger levels in different stretches.
- Main weather pattern
- Erratic weather produced localised heavy rainfall despite an overall rainfall deficit.
- Backwater effect
- The Ganga’s unusually high level made it difficult for the Gandak and Punpun to discharge their water.
- Embankment concern
- Embankments can separate rivers from floodplains, while silt deposition can reduce channel capacity.
- Recommended measures
- Suggested measures include restoring drainage channels, protecting floodplains, improving land-use planning, restoring wetlands and deploying early-warning systems.
- Regional coordination
- Greater coordination between riverine states is needed over reservoir releases.