Table 1 Exemplary of the effect of COVID-19 lockdown on water quality parameters

India

Ganga river

DO

–

2.3 mg/L

4.8 mg/L

2.5 mg/L

Khan et al. (2021)

Sabarmati River

TUR

24-Feb-2020 to 4-May-20

12.72 mg/L

8.08 mg/L

− 4.64 mg/L

Aman et al. (2020)

Varanasi's Nagwa Nala

DO

March 6 to April 4 2020

3.8 mg/L

6.8 mg/L

3.0 mg/L

Arora et al. (2020)

Vembanad lake

SPM

28th February 2020 to 16th April 2020

14.4 mg/L

12.1 mg/L

− 2.3 mg/L

Yunus et al. (2020)

Turkey

Meriç-Ergene River Basin (Ergene River and Çorlu Stream)

DO

Mid- January 2020 to early June 2020

8.9 mg/L

6.65 mg/L

− 2.25 mg/L

Tokatl and Varol (2021)

pH

,,

8.96

8.32

− 0.64

TUR

,,

22.46NTU

38.82NTU

16.42 NTU

TSS

,,

34.08 mg/L

49.16 mg/L

15.08 mg/L

COD

,,

32.82 mg/L

34.33 mg/L

1.52 mg/L

BOD

,,

8.23 mg/L

9.22 mg/L

0.96 mg/L

Northeast Italy

Venice’s canals

TSM

One month

3 g/m3

1.4 g/m3

− 1.6 mg/L

Niroumand-Jadidi et al. (2020)

China

Yangtze River Delta

WQI

March 2019–April 2020

66.0%

77.4%

11.4%

Liu et al. (2021)

Bhutan-India-Bangladesh Trans-boundary rivers

Mahananda (Siliguri st-1)

pH

Pre-lockdown (December 2019 and January 2020) and lockdown (April and May 2020)

6.85

7.44

0.59

Sarkar et al. (2021)

TUR

,,

17.95 NTU

11.05 NTU

− 6.9 NTU

COD

,,

52 mg/L

26 mg/L

-26 mg/L

BOD

,,

1.5 mg/L

2.05 mg/L

0.55 mg/L

TDS

,,

90 mg/L

96 mg/L

6.0 mg/L

DO

,,

6.85 mg/L

7.15 mg/L

0.3 mg/L

TSS

,,

56 mg/L

56 mg/L

0