Countries irrigated by an adequate river system are in many ways blessed. These rivers not only help agriculture, but they provide a cheap and efficient transport system for the development of internal trade. The saying goes—land divides, seas unite. But waterways bring also a good deal of misery to the people by causing devastating seasonal floods In India, for example, the sub-Himalayan regions of Uttar Pradesh, Bihar, Bengal and Assam are heavily flooded by the rivers of the Gengetic basin and the Brahmaputra, almost every rainy season.
It brings untold sufferings to the people of these low-lying plains. Millions are rendered homeless; men and cattle die in large numbers; the damage to property including standing crops is incalculable. Besides, floods affect the health of the locality and increase the incidence of cholera, typhoid and other water-borne diseases. In 1922 and 1998 flood in North Bengal left a trail of devastation, essentially in Malda, Murshidabad areas. Floods are caused by an excessive flow of water in rivers during the rainy seasons, due mainly to torrential rain in catchment areas.
This may be due to two natural causes. First, the melting of ice in glacier on the mountains may thus supply a river with volumes of water much in excess of its containing and carrying capacity. Secondly, heavy rains on the mountains cause an excess of water supply. In either case, the excess water overflows the embankments and submerges the low-lying plains. Bursting of dams and also Bridges in protective embankments lead to inundation. This causes large-scale deforestation. As for example, in the Terai regions during the war, floods destroyed the natural embankments of a river.
Occasionally earthquakes, by changing the course of a river, or by raising its basin or choking and silting the riverbed cause flood Another contributory cause is the construction of railway bridges without leaving provision for the natural outflow of flood-water. Of course, floods in an agricultural country have often been looked upon as a blessing in disguise. Floods leave behind on the submerged areas a rich alluvial or silt-deposit, which greatly increases the fertility of the soil.
This soil on either side of the Nile owes its fertility to the annual flooding of the area, which submerges large regions, even after the construction of Aswan Dam in Egypt. Nehru used to say—give unto the river what naturally belongs to her, i. e. homesteads should not be built on riversides or on temporary char lands. That is a sure preventive measure, better than steps to resist after-effects. Men have tried from the earliest times to build protective embankments against the incidence of floods. Ordinarily these can be made sufficiently strong to resist the usual type of floods.
A system of canals to irrigate the low-lying plains affords considerable escape route for the excess water caused by a normal rainfall. But these embankments should have to be maintained properly. Modern river engineering and hydro-dynamics, however, have led to a fundamental change in the principle. It is now realised that effective control of flood should begin at the source. Flood control, therefore, in these days has moved upstream. This includes the building of adequate reservoirs in the head stream area and the application of the principle of multipurpose river control.
The building of a sufficient number of reservoirs is a long-drawn and costly process. Public sentiment may not take kindly to it; for it necessarily causes large-scale displacement of population as has been noticed in the Narmada Banchao movement of Sm. Patakar. For taming the turbulent Damodar, the age-long ‘river of sorrow’, by constructing the Tilaya, Mython and other dams across her, many Bihar villagers had to be shifted, and this was not liked by the local population. The future, no doubt, belongs to successful working of multi-purpose schemes.
So petty objections, raised by individual or local interest, must give way before the larger needs of the people. In recent years, the rainy season has brought heavy floods all along the sub-Himalayan plains. The overflow of the tributaries of the Ganges and the Bramhaputra has caused untold sufferings to the people of these localities. Embankments have been broken, bridges have been washed away; villages have been waterlogged, cutting off all communications for days together.
The utmost damage has been caused to the towns and villages of Assam by the Brahmaputra floods. The government must put up protective embankments; help the easy drainage of water by removing artificial obstructions, and by adopting local remedies for particular regions. It has been rightly said, “Rivers that overtop their banks and flood the adjacent lowlands offer a challenge to the people who must be ready to protect their fields from inundation. “