IIT Guwahati researchers develop BRAHMA-2D model to understand flow of large braided rivers

Guwahati: The IIT Guwahati has said that a research team has developed a mathematical model to gauge the flow of large braided rivers like the Brahmaputra and help engineers while taking river bank protection measures.

The institute on Thursday said the indigenous river model named BRAHMA-2D (Braided River Aid: Hydro-Morphological Analyzer) may be helpful in the design of sustainable hydraulic structures like spurs, reverent and other river bank protection measures in order to check river bank erosion.

"Predicting river flow variations across depth is crucial for flood and erosion control, agriculture and water supply intake design, and zero head energy production. Traditional measurement methods of flow velocity in deep, large rivers during high monsoons is risky and extremely difficult, prompting the use of mathematical models. However, existing models provide only average velocity, underestimating undercurrents at different depths. In braided rivers, the presence of sandbars further complicates accurate three-dimensional velocity computation," said a statement issued by the IIT Guwahati.

River bank erosion is a serious issue in a flood-prone state like Assam, where the Brahmaputra and its tributaries create havoc during floods almost every year. Erosion has left thousands of families homeless and eroded agricultural land over the years. Research team said the model can be used in other large braided rivers too.

"With this quasi-3D river flow model, we can understand how fast the water moves at different depths inside a river and its circulation around a structure like a spur installed to prevent river bank erosion," said Arup Kumar Sarma, a professor of civil engineering department at IIT Guwahati. Sarma headed the research team.

The model was developed with the help of the Brahmaputra Board. It was successfully validated on the Brahmaputra river near Majuli Island, the second largest freshwater river Island in the world, in Assam, which is prone to river bank erosion.

BRAHMA-2D integrates a two-dimensional model of water movement with a theory about entropy, a measure of disorder or randomness. The research also delves into how features like river banks, spurs, and sandbars affect the way water moves. Specifically, it observes a dip phenomenon near spurs where the flow of water underneath increases, a phenomenon absent in points away from these structures, said the IITG statement.

The novel findings were published in the ISH Journal of Hydraulic Engineering, earning the paper the prestigious 'ISH Jal Vigyan Puraskar' (Best Paper in ISH Journal) 2023. The paper has been co-authored by professor Sarma and his former research scholar Anupal Barua, said the statement.