“Nepal has released water”, “Kosi is angry again”, “heavy rain in the hills”. This time the story doesn’t fit. Bihar got less rain than normal. From June till early September the state recorded about 601 mm, nearly 27 percent short. Still, more than two thousand villages in fourteen districts went under water. The Water Resources Minister said it himself — this year’s flood pattern was different. The Ganga rose first. The rivers that come from Nepal stayed quieter than people expected.

So where did all that water come from?

Bihar sits in a low, almost bowl-shaped stretch of land. Water from a huge area farther west and south has only one way out — through the Ganga. This season the Sone river brought a big surge. At Indrapuri Barrage the discharge crossed five and a half lakh cusecs in early September. That water reached the Ganga near Maner. Around the same time the Gandak near Hajipur and the Punpun near Fatuha were already high. The main Ganga itself was carrying a heavy flow eastward. When all of it arrives together, the river just cannot clear it fast enough. Levels at Gandhi Ghat and Danapur crossed marks not seen in years.

That is when the backwater effect begins. Think of a drain that is already full. Smaller rivers and the lower parts of bigger ones cannot empty into the Ganga because the main river is higher. The water has nowhere to go except sideways across the fields and into the villages. Places that sit near these meeting points start flooding even when the sky above them is only giving light rain. Officials noted that the discharge at Valmikinagar on the Gandak stayed below what they had prepared for, yet the flooding continued. The problem was not fresh water racing down from the north. It was water already inside the system that could not leave.

Silt makes the whole thing worse. Year after year the rivers bring sand and mud. The beds keep rising. Embankments that were built to keep water inside the channel have trapped that silt, so the channel itself is shallower than it used to be. A volume of water that might once have stayed within the banks now spills over more easily. In a season when overall rain is short, a few concentrated pulses from the western and southern catchments are enough to push everything over the edge.

People living along the Ganga in Patna, Bhojpur, Saran and farther east feel this every time the river stays high for days. Crops go under, roads disappear, and the familiar relief work begins. The difference this year is that the usual suspects — the Kosi, Bagmati and the northern barrages — were not the main actors. The Ganga’s own catchment, stretching hundreds of kilometres upstream, did the job.

None of this is new. Bihar has always been the place where water from a much larger area has to pass through a narrow, flat exit. What changes is the timing and the combination of flows. When the northern rivers and the Ganga peak together, the damage is huge. When the Ganga peaks first because of western and southern contributions, the flooding still happens, just from a different direction. Embankments, rising beds and the loss of natural spill areas turn a manageable rise into widespread inundation.

So the next time someone says Bihar floods only because of Nepal, the numbers this season give a clear reply. Local rainfall was short. The northern rivers did not deliver the expected surge. The water that filled the Ganga came from farther west and south, backed up the tributaries, and spread across the plains. That is the quieter, less dramatic, but very real reason the villages went under while the rain gauges stayed low.

Sources:

Civilsdaily report on Bihar’s rainfall deficit and flood pattern, Prabhat Khabar coverage of the minister’s statement, India Today explanation of the Ganga rise at Patna, and Bihar Disaster Management Department bulletins from early September 2026.

@⁨Rohit Manral⁩