Critical appraisal of water quality model parameters for an urban city in lower Ganga basin during pre- and post-COVID19 Lockdown in India

Objectives: To assess the impact of urban city Patna on water quality river Ganga during pre and post COVID-19 lockdown. Method: A study is done to point nonpoint source pollution at different reaches for years 2017 2020 (at a stretch 40 km in lower plains). total 450 datasets have been collected from eight locations two major drains. The equations deoxygenation reaeration coefficient used modelling tested their applicability area. Findings: Analysis data 8 2-drains year 2017-2020 shows significant improvement variables observed due reduction influx non-point including floating population COVID19 lockdown (March- June 2020). use BOD-DO developed by Streeter-Phelps (1925) as Oxygen-Sag curve still valid, if input are limited. However, Camp (1963) Jha et al. (2007) may be effectively comprehensive sets. Moreover, refined model predicting has dissolved oxygen (DO) biochemical demand (BOD) pre- individually. maps using satellite (Landsat-8) provides turbidity levels countrywide period resulted improvement. Novelty: unique analysis its comparison with previous data. coefficients values established pre-and COVID period. Also Landsat-8 assessing post-COVID19. Keywords: pollution; 19; BODDO modelling;