Flood History

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  • Topic: Flood, Brahmaputra River, Dam
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  • Published : July 28, 2010
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Flood History

 
1. Introduction:
              Riverbank erosion during high flood period in the valley is a regular annual feature. Over bank flood due to breaches in the embankment render the fertile cultivable land unsuitable for crop production due to deposition of coarse sand on the surface to a variable depth. As per Assam Government Revenue Dept. records, an area of 6116 hectares of land was affected by soil erosion in Upper Brahmaputra Valley and North Bank Plain zone during 1994.                Heavy pressure exerted by high floodwater on the embankment wash away the weaker portions of the embankments and inundates the nearby areas with consequent effect of heavy silt and sand deposition on the fertile cultivated fields.       Before 1950 floods occurred in Assam in 1897,1910, 1911, 1915, 1916, 1931, mainly in the north bank of river Brahmaputra       After 1950, floods occurred in Assam in ’54, ’62, ’66, ’72, ’74, ’77, ’78, ’ 84, ’86, ’87, '88, '89, '90, '91, '92, '93, '94, '95, '96, '97, '98, '99, '2000, and is still continuing. 2. The Indian Scenario - A Glimpse

Flood Damages in India 1953-1994
Item| Average (1953-1994)| Maximum|
Area affected (in Million hectares)| 7.56| 17.5 (1978)|
Population affected (in millions)| 32.0| 70.45 (1978)|
Cropped Area affected (In Million Hectares)| 3.53| 10.15 (1988)| Damage to Houses (in millions)| 1.17| 3.51 (1978)|
Number of Cattle Lost| 96,713| 6,18,248 (1979)|
Number of Human Lives lost| 1504| 11,316 (1977)|
Damage to houses, crops and  public utilities (in Rs. Crores)| 982.1| 4630.3 (1988)| 3. Flood in Assam
A summary of the flood damages in Assam (1953 - 1995)
ITEM| TOTAL| MAXIMUM|
        Area affected (in Million hectares)| 41.66| 3.82 (1988)|         Population affected (in millions)| 98.10| 10.47 (1987)|         Damage to cropsA)    Area (In Million Hectares)B)     Cost (in Rupees Crores)|  5.083288.31|  1.13 (1988)334.10(1988)|         Damage to HousesA)    In numbersB)     Cost (in Rupees Crores)|  33,27,189296.80|  4,99,835(1988)103.92(1988)|         Number of Cattle Lost| 4,31,537| 1,08,913 (1987)|         Number of Human Lives lost| 1724| 226 (1988)|         Damage to  public utilities (in Rupees Crores)| 832.42| 225.82 (1988)| Period I: 1950 to 1980 

Floods have been a regular feature during the period 1950 to 1980. Although all data are not available for the period, the following data that could be collected during the study period helps us appreciate the intensity of the damages caused by floods to Assam during these three decades. In certain cases break-ups of the data are not available and hence the figures are put in the manner in which they are available. During the period 1954-55 to 1968-69,

        Nos. of eroded villages     :                 2534         Nos. of affected families   :                90726         Area affected                   :               294421 acres 1953-1978: - total loss of property amounted to 122 crores

In 1964 a Central team commissioned to evaluate the flood situation in Assam reported 6.5 m. (average) sand deposited in the Brahmaputra river bed after studying the entire reach from Sadiya to Dhubri. Over the years 1970-1979, the loss of property and crop on an average was not less than Rs. 10 crores per annum. In 1972, a significant development was the formation of a "ministers' committee" on flood relief. The year 1978 was relatively flood free. Devastating floods occurred during 1979 & 1980. During 1980, two successive waves of flood occurred, the first in the month of July and the second in August.

Damages caused by floods in Assam (1954 -1970)
 
 |  | 1954| 1958| 1962| 1966| 1970|
1| Area affected (Lakh Hectares)| 29.00| 12.29| 15.95| 15.11| 7.58| 2| Cropped area affected (Lakh Hect.)| 3.05| 0.25| 3.61| 3.69| 2.26| 3| No of villages affected| NA*| NA| NA| NA| NA|

4| Population...
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