“Make room for the river”. Higher you raise the levees or embankment; a river in flood will find the weakest spot and burst through.

Majuli Island is suffering from recurring flood and erosion. Since 1950 earthquake the river bed of Brahmaputra raises which lead to excessive flood and erosion problem in Majuli Island. After 1965 Ahataguri 21-mile have been washed away by river Brahmaputra, now some parts of Ahataguri mauja is present. The total land got washed away by flood and erosion is 308.27 hectare in the year 1998. Salmora Mauja - 116.93 hectors, KamalabariMauja - 30.99 hectors, AhataguriMauja - 156.58 hectors.

The Island suffers from severe bank erosion on its southern side due to the erosive action of Brahmaputra River, and on its northern side due to the Subansiri River. The river island is subjected to severe annual floods under the influence of the South West monsoon. The erosion is mainly attributed to extreme sedimentation and to the main river traversing through a series of deep and narrow throats, and formation of the sand bar in the midst of the river. Along the channel of the Brahmaputra river bank, uneven bank-slumping is a characteristic feature.

Government Measure for Majuli Island:

The problem of the Majuli Island is being tackled by the Government of India on a short term as well as long-term basis. As regards short-term measures, the Brahmaputra Board had constituted a Committee of Experts comprising senior officers from Water Resources Department, Government of Assam, Central Water Commission, Central Water and Power Research Station and Brahmaputra Board to identify and suggest immediate anti-erosion measures to be taken up for protection of Majuli Island. On the recommendations of the Committee, the Brahmaputra Board had formulated a scheme amounting to Rs.6.22crore for taking up immediate anti-erosion measures for Majuli Island for reduction of the problem of flood and erosion to a considerable extent.

As regards long term measures, the Brahmaputra Board prepared DPR amounting to Rs.86.56 crore for Protection of Majuli Island from Flood and Erosion. The scheme is to be implemented in phases. Part of the works is dependent upon model studies of the entire vulnerable reach of the Island. Phase-I works costing Rs.41.28 crore (not depending upon model studies), has been approved by Govt. of India in January 2005 and taken up by Brahmaputra Board. The balance works will be taken up on the recommendation of the model studies.

Important works executed under three phases are:-

(a) The closing of breaches

(b) Raising and strengthening of the embankment

(c) Casting and lying of permeable RCC porcupine screens/spurs/dampeners at various locations.

Embankment failure: There are 12 embankments in Majuli Island out of that 8 embankments have become less preventive capacity to withstand flood as said by Society for Socioeconomic Development in the Region published in daily News Pratidin on 6th December 2013. As said by the Society that 8 embankments have achieved their date of expiration. The date expiration of Kherkhuti embankment was 1991, Tekelifuta Haldi Badi embankment was 1981, Kherkhuti embankment was 1981, Haldibadi– Bessamera embankment was 1978, Kamalabdi- Budha Kalita embankment was 1980, Budhakalita – Kakorikota embankment was 1987, Subansiri from 10 to 21 mile embankment was 1995. Protection of Sonowal Kachari Embankment as it acts as a Life Line of Majuli Island. The figure showing breech took place in Sonowal Kachari Embankment in 2012.

           Fig: SonowalKachari Embankment, 2012 embankment failure

A new embankment has been constructed replacing the old breech area of Sonowal Kachari embankment for flood protection. Therefore protection of this embankment is becoming the prime concern.

Figure: Showing New SonowalKachari Embankment

Bio-Engineering in abating Erosion in embankments and flood plains:

Management strategies for preserving areas affected by Flood and erosion:

Project Implementation in DRR for plantation: 

1. Site Preparation & Construction

2. Planting

3. Monitoring

4. after care

Plantation of trees which are commercially important and herbaceous grass along the bank of the river should be encouraged e.g. C.dactylon, S.spontancum and V. zizaroides and I. cerenae. These plants also have high soil binding capacity. Cynodondactylon and Saccharummunja have a soil binding capacity of 90 to 97% and 92 to 96% respectively and both of these species were found to be very effective in checking erosion in the Ganga and Varuna rivers.

Social Forestry Program:

1.     Sand Bars should be used for social forestry program.

2.     This will helps in stabilizing the sand bars.

3.     Through Social forestry, it will help in providing fodder for cattle, fuel wood etc

4.     Encourage local people in plantation and monitoring trees.

Proper engineering techniques should be adopted to harness the river from flood and erosion. Specific height should be made for the water to spill in and out. High you raise the levees or embankment; a river in flood will find the weakest spot and burst through. Therefore instead to set aside land for flooding — to "make room for the river”.

Restoring rivers also requires recreating old channels and meanders, re-vegetating banks, and reconnecting rivers with their floodplains.

Increase vegetation cover along the flood plain. The main technique is dumping trees in the river. Need large structures — they are very important for slowing down water and trapping organic material," says Johanna Gardestrom, an ecologist at Umea University. "The trees are also food for aquatic insects, which in turn are food for fish." Another benefit of putting trees back is to keep rivers cool. Trees can cut two degrees off water temperatures and up to five degrees if there is a full cover."

1. Improve the habitat of fauna and Avi-fauna.

2. Improve the socio economic condition of people (Employment generation of local people (Plantation and monitoring) and generation of income by the commercialization of plants product.)

Another benefit of putting trees back is to keep rivers cool. Trees can cut two degrees off water temperatures and up to five degrees if there is the full cover."