Identifying the Pollution Sources of River Yamuna through Field Observations and Participatory Approach

Abstract: River Yamuna, flowing through the National Capital Territory (NCT) of Delhi, is considered as one of the worst polluted river stretches in the world. The river is primarily polluted through untreated sewage discharge from various point and non-point pollution sources that find their way through storm drains and join the river Yamuna. One of the major requirements to address urban water quality is to identify the potential sources of contamination in a large drainage basin, which is challenging as the basin area is so big that it is difficult to pinpoint the source of pollution. Invariably, as the pollutants move into the drains under gravity, it is possible to identify the drains and their corresponding catchment areas that have higher pollution load. Thus, the study aims to find the sources of pollution in a larger river basin by integrating field observation, GIS approach, and qualitative interviews. Water samples from 43 monitoring locations are collected in the various storm drains of the Barapullah drainage basin, in various primary, secondary, and tertiary drains, and analyzed the water quality parameters in the Delhi Jal Board (DJB) water quality laboratory. The locality-wise spatial contribution of pollution is mapped in the context of the Barapullah basin. The study results found excessive BOD values ranging from 37 to 430 mg/L, and six major pollution hotspots were identified. The qualitative interview conducted in the six major pollution hotspots regarding the source of pollution and results indicated that the discharge of domestic sewage from planned colonies, unauthorized colonies, and JJCs, as well as market waste disposal, are the potential reasons for pollution in the six major pollution hotspots. This pilot-level study provides a useful and effective approach to investigating and identifying pollution sources, mitigating the pollution at the source, and ultimately reducing the pollution level at river Yamuna. Research Highlights: Water quality assessment is performed for different storm drains in the Barapullah basin of NCT Delhi. All the monitoring locations recorded an excessively high amount of BOD against the CPCB standard. Sub-catchment areas contributing to higher pollution are identified and mapped using GIS, for the Barapullah basin. Major pollution hotspots are located through Citizen Science approach.