Are River Embankments the Best Solution for Flood Control?

In December 2016, Robert James Wasson and colleagues from the Institute of Water Policy, Lee Kuan Yew School of Public Policy, National University of Singapore, Dibrugarh University, and TERI University travelled to Dibrugarh in Assam (India) to research the effectiveness of embankments as a flood management strategy.

 

The mighty Brahmaputra

The Brahmaputra is one of the world’s greatest rivers. On the basis of the annual average runoff, the Brahmaputra is ranked first and eighth in the Indian sub-continent and the world, respectively (510,000 million m3).

This trans-Himalayan river is approximately 2,900 km in length and drains an area of 580,000 km2 in Tibet, India and Bangladesh. Some segments of the river can be as wide as 10 km.

 

The annual flood of the Brahmaputra – Son of Brahma, the God of Creation – is a lifeline of millions. The flood delivers rich and vital nutrients to the Assam Valley between the foothills of the Himalayas to the north and the Khasi and Garo hills to the south.

 

On the flip side, these floods can also be a cause of death and destruction. In the latter half of the 20th century, an estimated 42 million hectares of land and a population of over 98 million have been affected in the state of Assam. Some 5 million hectares of agricultural lands have been destroyed and over 1,700 human lives have been lost.

 

River embankments as a flood management strategy 

One of the main flood management strategies adopted by the government of India following the launch of the National Policy on Floods (1954) is the building of embankments. Between 1954 and 1990, the length of embankments more than doubled nationwide. Today, more than 5,000 km of embankments have been built in the Brahmaputra Valley.

 

Stone spurs were built as energy dissipators to protect embankments from scouring and erosion.

 

These embankments have afforded some form of flood protection to the rural and urban dwellers and villages have mushroomed around the embankments, such as this village school. But they are also susceptible to breaches.

 

The research trip investigated specifically questions and concerns such as: what impacts do embankments have on river dynamics? Do embankments reduce perceived flood risk? What is the narrative content of the ‘public pressure for action’? What are the costs and benefits of river embankments from the perspectives of different stakeholders? What are the reforms and institutional changes required to strengthen embankment governance? How can non-traditional sources of flood data help flood risk estimation?

The fieldwork is part of a research project titled River Embankments: Reality and Perception in a Systems Approach

Photo credit: Joon Chuah

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