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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

3. Flood in Assam

A summary of the flood damages in Assam (1953 - 1995)

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)

(Source: Directorate of Economics and Statistics; Assam)

Damages caused by floods in Assam (1973-1980)

(Source: Revenue Department, Govt. of Assam.)

1981 floods: In 1981 a total of three waves of floods occurred.

1984 floods: As many as five successive waves of high flood occurred in the state in the year 1984, which resulted in tremendous loss in terms of lives, property, standing crops, etc. The first flood wave during the year 1984 occurred in the month of May, the second in June, and the third and fourth in July. These waves of flood affected almost the entire plain districts of the state. From the second half of September 1984, another wave of flood of unprecedented magnitude occurred in the state, which badly affected ten districts of the Brahmaputra Valley.

1985 floods: The state suffered another series of floods during 1985. In the Brahmaputra Valley the first wave of flood occurred during June 1985, and the second occurred during July 1985, the first wave of floods affected six districts of the valley while the second wave affected as many as eight districts of the Valley.

Damages caused by floods in Assam (1981-1985)

 (Source: Revenue Department, Govt. of Assam.)

1986 floods: In 1986, the flood situation again was very grim with the water level staying above the Danger Level for 26 days - 6 days in June, 3 days in July, 4 days in August and 9 days in September. Some of the highlights of this year's flood were:

§         On 25^th August the water level was 87.09 m.

§         On 15^th Sept. the water level was 105.14m (D.L. 104.24 m.) at Dibrugarh.

§         At Jorhat (Neamati) the water level was above the danger level for 26 days.

§         On 16^th September at Jorhat (Neamati) the water level was 86.04m (D.L. 85.04m.).

1987 and 1988 floods: Analysis of flood data indicates that the intensity of floods is increasing year after year. The floods occurring in 1987 was so intense that many termed this flood as unprecedented. This year’s flood affected 90 Lakh people in Assam. The floods in 1988 turned out to be even more devastating. This year the water level reached 2.20 m. above the danger level. As much as 4.22 million hectares of land estimating about 28.05% of the total area of the state was affected by flood in 1988 damaging a record cropped area of 1.13 million hectares. As the geographical area of Assam is 754 million hectares, the flood prone area averaged about 40% until 1988, but with the largest flood in 1988, the flood area went up to 62%. However, if the two hill districts, Karbi Anglong and North Cachar are excluded to get approximation of the extent of flood in the plains area of Assam, 77% or over three-fourth of the plains of Assam is flood prone and went under water in 1988.

Damages caused by floods in Assam (1986-1993)

 (Source: Girin Chetia: Magnitude of the problem of flood in Assam and its trend. In: PLAVAN, Vol IV, June, 1999.)

1997 Floods: As usual Assam experienced a series of devastating floods during the year under report from the first week of June 1997 which continued till September 1997. Available information relating to flood damage reveals that altogether 5408 Nos. of villages of the state covering an area of about 7.53 Lakh Hectares were affected by the Floods during 1997. The cropped area affected was 1.03 Lakh Hectares while population affected numbered 27.51 Lakhs. It also claimed 28 human lives and 1961 Nos. of livestock. Houses damaged was reported to be 18104 Nos. The value of crops lost and houses damaged by the flood during 1997 has been estimated at Rs. 19.46 crores and Rs. 9.98 crores respectively. The damages to public utilities have been estimated at Rs. 6.92 crores. Moreover the floods also caused heavy soil erosion in the riverine areas of different districts of the Brahmaputra Valley. The worst affected areas due to soil erosion were North Lakhimpur (31235 Hectares), Darrang (9877 Hectares), Hailakandi (3404 Hectares), Nalbari (1402 Hectares), Cachar (1818 Hectares), Dhubri (599 Hectares), Bokakhat (404 Hectares), Dhemaji (206 Hectares), Hatsingimari (189 Hectares), Kamrup (133 Hectares), Goalpara (69 Hectares) and Majuli (15 Hectares).

1998 Floods: During the year the flood situation in Assam further aggravated the economy, throwing lives out of gear in as many as 21 districts of the state starting from 10^th June 1998, the devastation of floods continued upto 15^th September 1998 without any respite. Except the two hill districts of the state almost all districts of both the Brahmaputra and the Barak Valleys were subjected to heavy floods during the year. The available information relating to flood damage reveals that altogether 7740 Nos. of villages of the state covering an area of about 13.2 Lakh Hectares were affected by the floods during 1998. The floods of 1998 also caused heavy soil erosion and the total area eroded during 1998 was estimated at 5634.22 Hectares of land. The worst affected areas due to soil erosion were Sonitpur (1109 Hectares), South Solmara (511 Hectares), North Lakhimpur (368 Hectares), Barpeta (257 Hectares), Kamrup (489 Hectares), Morigaon (995 Hectares), Bilasipara (167 Hectares), Jonai (72 Hectares), Bijni (57 Hectares), Tinsukia (Hectares) and Goalpara (46 Hectares).

Damages caused by floods in Assam in 1994-1999:

(Source: Flood Control Department of Assam, Ghy.)

Source: Assam Govt. Annual Report on Flood Hazard)

The per annum area affected by flood and annual average cropped area affected shows an increasing trend from 1950. During 1988-89, it was as high as 98% of the total flood damages. Analysis of data on the extent of area affected by flood in Assam further reveals (1952-1993) three yearly cycles, indicating the severity of flood after the third year.

2000 floods: In the year 2000 too, as in previous years, the state had to incur the wrath of the floodwaters. A detailed description of the scenario is given below:

First spate of flood (11^th June):

Damage in Arunachal Pradesh:

¨      15 people died in Siang, Pasighat and Yinkiong of Arunachal Pradesh

¨      3000 families heavily affected

¨      5000 families rendered homeless in Upper Siang, East Siang, Pasighat, Yinkiong, Panggin, Sakopo

¨      Bridge washed away at Nabagiri (Upper Siang, Diet Dime (Siang), East Siang

Damage in Assam:

¨      Erosion started along Brahmaputra Right bank from Oiramguri Ghat to Jonaimukh about 30 Km. in length. Villages affected: Mazgaon, Nalanipam, Kerker, Bogoritoli, Bholukaguri, Kutumgaon, Bera Mazgaon, Mechgaon, Tinmileghat, Luitpur Deuri, Tarimazgaon, Raibasti, Berachapori, Machowa camp, Pova, Haripur Mishing, Haripur Deuri, Roktebogori, etc.

Second spate of flood (23^rd June):

Damage in Assam:

¨      From Government sources in newspaper:

Ø      447000 people affected in 12 districts

Ø      27608 hectare land affected

Ø      11200 hectare cropped area affected 

Total 26 GPs, 226 villages, 6288 families, 38118 persons, 6217 livestocks were affected.

¨      Breaches:

Ø      Kathalguri: 1Km.

Ø      Bhangidiya: 300 m

Ø      Borchapori: 1Km.

¨      Gai-Brahmaputra flood:

Ø      Affected GPs: Sissiborgaon, Ujoni Sissi tongani, Madhya Sissi tongani, Namoni Sissi Tongani, Borlung, Muktiyar and Akajan GP (Total = 120 villages)

¨      Jiadhal, Kumotiya flood:

Ø      Affected GPs: Moridhal, Jiadhal, Samarajan, Narua Than, Ajuha, Ghaguha, (Total = 31 villages)

¨      Gai-Korha-Brahmaputra flood:

Ø      Affected GPs: Jorkata, Sissimukh and Benganagora (Total = 25 villages)

¨      Subansiri flood:

Ø      2000 persons in 22 villages affected

¨      2^nd July 2000: Dhemaji district authorities declared that 172998 persons of 380 villages were affected, the break up being 105335 persons in 205 villages of Jonai Sub-division and 67663 persons in 175 villages of Dhemaji sub-division.

Third spate of flood (5^th August):

Ø      8 people died – Bijoy Chutiya in Bhebeligaon

Ø      20 Lakh people affected

Ø      65 villages in Dhemaji sub-division.

¨      Damage in Jonai Sub-division:

Ø      Agriculture: Rs. 1.5 crores

o 2237 hectares Ahu o 529 hectares Sali o 19.8 hectares Jute o 2.5 hectares Sugarcane o 104 hectares vegetables o 14 hectares horticulture

Ø      Road and Bridges (PWD): Rs. 44 Lakhs

Ø      Road and Bridges (National Highway 52): Rs. 30 Lakhs

Ø      Livestock: Rs. 8 Lakh (6000 Nos.)

o 2868 cows o 1104 buffaloes o 500 goats o 270 pigs o 1172 poultry o 595 ducks

Total estimated damage: 2 crores and 32 Lakhs.

Flood level in the Brahmaputra River at different dates and places in 2000

Maximum damage caused by floods in Assam

(Source: Patra and Kalita; Flood of Upper Brahmaputra Basin is an International Problem. In: PLAVAN, Vol-IV, June, 1999)

Average values of damages caused by floods in Assam

(Source: Patra and Kalita, Flood of Upper Brahmaputra Basin is an International Problem. In: PLAVAN, Vol-IV, June, 1999)

4. DISTRICT-WISE DATA FOR FEW YEARS                                                                            

Flood Damage in different districts of Assam (1974)

Flood Damage in different districts of Assam (1997 - 1999)       

District-wise damage data for the year 2000

(Source: Revenue Department, Govt. of Assam)

Damages in North Lakhimpur sub-div. (in undivided Lakhimpur district) due to flood: (A)

*Damage in the N. Lakhimpur sub-div. in the year was negligible – only the riverine areas of river Brahmaputra were affected.

 (B)  

* I maund = 40 kg.

 (C)  

(Source: District Gazetteer of Lakhimpur District 1971.)

5. BLOCK-WISE DATA IN DHEMAJI COLLECTED OVER A FEW YEARS            

Achievements

Work undertaken by Brahmaputra F.C. Commission in Brahmaputra Valley (1976-2000):

 (Source: Flood Control Department, Assam, Guwahati)

The following table gives some details of Dhemaji Flood Control Department schemes