Question

to prevent bihar from the curse of flooding. answer plzz

Answer 1

A number of structural measures can be taken up in the state to prevent bihar from the curse of flooding:

Detention Basins: The state area has a number of depressions locally called chaurs which act as detention basins. These chaurs absorb a considerable amount of water of the first flood of the season. No man made detention basins or improvements in natural chaurs has been done.Embankments: All the rivers have been embanked in the state. River Kosi is embanked on both the sides. But there are few gaps in these embankments which reduce its effectiveness. The maintenance and repair of these embankments must be taken into account.Channel Improvement: is not a usual practice which can be improved. also broadning of rivers is also an good measure to prevent water to overflow from it.

Answer 2

To keep the river channel deep and free from siIt, and the course of the river straight—this is the only acceptable aim of river graining which dams and revetments do not secure. Dead and dying rivers are a curse; silking and rising river beds aggravate instead of preventing floods. Bengal engineers, therefore, have very good reasons for fighting shy of embankments. 'This docs not mean that they are prepared to resign themselves to the ravages of Hoods, Modern engineering can improve upon indigenous methods for dcepening river beds and keeping them silt free. Flood damages from rivers in Bihar, North Bengal and Assam can be prevented by parallel works of permeable screens constructed with materials that are available locally and the work can be done by local labour, under local supervision, as bandalling is well known on North Indian rivers. It will not be necessary to have foreign experts, nor much foreign exchange. The author who had been intiamately connected with rivers in Assam and Bihar, as Special Officer, Rivers, in the Assam PWD and Member, Development Hoard, Bihar, argues persuasively for the adoption of permeable screens. A summary of the principal findings and conclusions precedes the. article. Summary H E floods have affected 30,000 square miles in Bihar, North Bengal and Assam, where 10 million people live, the damage being Rs 100 crores. Only flood-stricken people can realise what a calamity it is. Excessive precipitation is beyond the control of man. Attempts have been made by man to reduce the ill effects of excessive precipitation, the methods adopted being: (1) Embankments to confine the waters within the river. (2) Afforestation to reduce the run-off from a river catch-ment. (3) Dams and reservoirs to reduce river flow. (4) Channel improvement to in-crease the discharging capacity. The evils of embankments are well known. In China, embank-ments have caused a gradual rise in river bed and flood heights, neces-sitating rise in embankment heights, so that the Yellow River now flows high on a ridge of the alluvial plain. A breach in its banks causes sudden submergence, and in 1897 led to the death of a million people. EMBANKMENTS CONDEMNED In the USA, between 1777 and 1927, embankments along the Missis sippi had to be raised 17 feet higher. Yet the 1927 floods caused breaches and 350 people died. Embankments arc destroyed by river erosion. 'Thus in the Yazoo Embank-ment District, 305 miles of new embankments have been constructed on successive retired alignments, to maintain the 178 miles originally constructed. In India, embankments have gene-rally been condemned. A Chief Engineer, Bihar, considers that embankments are " in no small mea-sure responsible for the present troubles ". Embankments cost large sums of money, are unremunerative and do not provide protection against major floods. Afforestation, terracing, or con torn bunding, has little effect on the volume of water that runs off a river catchment, during periods of pro-longed heavy precipitation, when rivers break into flood. Dams and reservoirs can effect a reduction in the volume of flow, thus lowering flood heights in the lower river. But as an alluvial river automatically adjusts its channel to correspond to its flow requirement, reduction in flow leads to deteriora-tion, and in a few years the lowering effect of flood heights in the lower river is vitiated, That a reduction in the volume of flow deteriorates a river channel is evident from the example of the Bhagirathi after the diversion of Ganga water through the Padma, and that of the Ganga after diver-sion of its water through the irriga-tion canals. Floods have occasionally readied great heights, causing immense damage, even when a river is carry-ing a comparatively low discharge. 'Ibis happened in July 3943 in the Damodar, when it was carrying a discharge of only 300.000 cusees or less than half that of 640,000 cusecs, which it drained away without flood damages in 1041. Similarly flood occurred in the Kosi in 1953, when it carried a discharge of only 2.30,000 cusecs, less than half that of 470,442 cusecs, which it drained away