Pooja, Pamposh and Rita Singh
Abstract
Najafgarh drain is the largest drain in Delhi, which enters Delhi at the Dhansa barrage and joins the river Yamuna at the Wazirabad barrage, contributing about 60% of the cityâs wastewater to the Yamuna River. In present study, the water quality and heavy metal analysis was done from Dhansa barrage to Wazirabad barrage was carried out during 2022-2023. Water quality assessment through WAWQI and HPI, based on CPCB and BIS standards, showed extremely poor conditions of water quality, with WAWQI 917.73 at Dhansa (S1) to 2010.47 at Wazirabad (S10) classifying all sites as unsuitable for drinking. The HPI (189.54 at S1 to 1593.67 at S10) indicating severe heavy metal pollution. Cluster analysis identified different pollution gradients along the drain, with water quality deterioration due to untreated sewage, industrial discharge, and inputs from multiple secondary drains. Results show that pollution originates from multiple sources, with the discharge from associated secondary drains being the major contributor to the deterioration of the drainâs water quality, which affects the Yamuna River. Najafgarh Drain is severely degraded along its entire length within Delhi, with water quality deteriorating progressively from Dhansa Barrage to Wazirabad Barrage. The study emphasizes the immediate necessity for better wastewater treatment and comprehensive management approaches to control pollution.