The Ganga Morphology - The Ganga: Water Use in the Indian Subcontinent - page 37

Floods are regular occurrence in this region, which peak in July and August but
they do not make news, because other areas in the Ganga's flood-plain are affected
simultaneously. Human habitation on this flood-plain, particularly in response to
the hazard, has a lot in common with other parts of the country. Historically, the
Gangetic plain has been a marginal preference for permanent human habitation. It
was only a century ago that human habitation began in the flood-prone plains of
the Ganga basin, which intensified after the Partition of the sub-continent in 1947
when hordes of displaced people migrated from Sind and western Punjab in Pakistan
and settled in this region. The less densely populated flood-plains provided new
sites for rehabilitation. Despite lack of experience in tackling occasional floods, the
immigrants availed credit offered by the government and used modern techniques
of farming commercial crops like sugarcane and wheat. The government gave land
too to the refugees and helped them settle in unfamiliar and mostly flood-prone low
land. For instance, the new Hastinapur town came up in this manner. The flood-
plain hummed with noise of tractors, tilling the virgin land and new villages and
growth centres emerged. Small-scale industries, like sugar and flour mills and petty
engineering workshops also came up.
Thus in the upper catchment areas of the Ganga in parts of Uttarkashi, Chamoli,
Pauri, Tehri, Dehradun and Almorah districts, many braided and meandering
streams with swinging courses flowed into the Ganga. Soil erosion and gully forma-
tions took place in steep slopes. Deforestation and faulty farming caused frequent
landslides. Mass rehabilitation encroached on the flood-basin and farming activities
enhanced the silt-load, besides eroding banks, which in turn accelerated morpho-
logical changes in the river. The discharge suddenly increased below the confluence
with Yamuna at Allahabad and caused more flood. Spills during high floods dam-
aged the river and erosion increased near Varanasi, Balia, Mirzapur and Gaighat.
Braiding and meandering also continued with the formation of alluvial fans, point-
bars, swamps and marshy land, following deposition of alluvium, varying the
river-width on the flood-plain from 5 to 15 km.
The Ganga enters Bihar near Buxar and after flowing about 450 km enters West
Bengal near Maniharighat. On this long stretch, it also meandered and braided and
the width on the flood-plain ( khadir , in local parlance) goes up to about 15 km.
Below Mokameh, it swung south from 1957 and eroded the south bank. Further
down of Surajgarh, the river swung between Mungher and Mansi; it flowed in the
vicinity of the former in 1936 but gradually moved north. By 1963, it eroded banks
very fast, threatening the rail-line near Mansi. The peak discharge at Mokamah in
1969 was of the order of 73,620 cumecs. Spurs were put to shift the river south-
ward and occupy the course it did in before 1936. Major sub-Himalayan tributaries,
like Ghagra, Gandak and Kosi also brought huge quantities of silt, which changed
braiding and meandering of the Ganga. It was observed that when the river went
into high spate, the discharges from the tributaries were blocked, flooding the sub-
basins and confluence points. This worsened when there was flood in the river and
its tributaries, simultaneously (Fig. 5.2).
The Ganga's bank erosion in Bihar was primarily due to changes in the mean-
dering courses. The stretch from Mokamah to Rajmahal was very badly erosive.