Fig. 4.
(a) Daily river discharge measured at Pontelagoscuro gauging station compared with monthly climatology for the period 2010–2019. Diamonds represent average Water Turbidity values extracted from satellite maps near Pontelagoscuro station (lockdown period is marked in blue); the three vertical line indicate the Water Turbidity maps on (b) 19 March, (c) 8 April, and (d) 23 April 2020. (e) Scatter plot of the MSI-derived turbidity vs daily river discharge, measured at Pontelagoscuro gauging station. (f) Scatter plot of the spectral slope of MSI-derived Rrs between 665 nm and 704 nm (see Methods) versus daily discharge of Po River, recorded at Pontelagoscuro. NDCI was calculated with Eq. (1) (see Methods). Water turbidity was retrieved according to Dogliotti et al. (2015). Colours indicate the pre-lockdown (yellow), the lockdown (blue), and the post-lockdown (red) periods.