Identification of foam susceptible locations in the Delhi Reach of the Yamuna River

Recently, the occurrence of foam formation across many rivers has been a cause of concern for the global scientific community. The primary reasons behind foam formation include anionic surfactants, nutrients, organic and inorganic substances, and pathogens, which have been widely studied in the past. However, the issue of foam formation on water surfaces and identifying foam-susceptible locations has not been addressed comprehensively in the past literature. To address this, the present study, for the first time in river management literature, proposes a unified framework to investigate the foam formation issue and identify foam-susceptible locations over Delhi’s reach of the Yamuna River, a stretch known for witnessing extensive pollution and excessive foam formation. The foam-related parameters were initially identified, and efficiency scores for four locations—Wazirabad Barrage (u/s), ITO Bridge, Nizamuddin Bridge, and Okhla Barrage (d/s)—were evaluated using the data envelopment analysis model. It was observed that three locations demonstrated low-efficiency scores in comparison to Wazirabad (u/s), indicating a high susceptibility to foam formation, which is critical from an environmental perspective, characterized by elevated levels of nutrients, surfactants, and organic pollutants. The reduced freshwater availability, lack of dissolved oxygen, discharge of untreated or partially treated effluents from multiple drains, and high concentrations of surfactants were noticed, which necessitate focused interventions in this area. In response, the study recommends remedial measures, including ensuring adequate environmental flow, pollutant oxidation, phytoremediation, stringent regulations, and public awareness to address foam formation issues in the Yamuna River.