The Yamuna is notorious for its iceberg-like clusters of white foam that drift across the water’s surface, especially in Delhi’s Okhla Barrage.
But what causes this phenomenon that stays on even during the monsoon?
According to a study by the Delhi government, foam formation in the Yamuna is not solely due to synthetic ‘surfactants’ but may also be influenced by biogenic inputs, especially from invasive aquatic species like Eichhornia crassipes (water hyacinth).
Eutrophication-induced plankton blooms, longchain fatty acids, nitrogen gases, and even proteins enhance foam stability.
According to the study, turbulence caused by the Okhla Barrage also plays a physical role in promoting foam generation by injecting gas bubbles into the surfactant-laden water column.
“Despite policy-level interventions under the Yamuna Action Plan and Namami Gange Programme, gaps remain in enforcement and integrated watershed management,” the report concludes.
The froth is one of Delhi’s most visible environmental challenges and is yet to be vanquished.