Quantifying human pressure
We quantified human pressure using the human footprint index (HFP), calculated for each year in each river site (https://wcshumanfootprint.org/map/; Venter et al. 2016). Due to insufficient available data, the 2020 and 2021 HFP was not used. The HFP incorporates into a cumulative index eight single human pressures: (1) built environments, (2) crop land, (3) pasture land, (4) human density, (5) nighttime lights, (6) railways, (7) roads and (8) navigable waterways (Venter et al. 2016). This index ranges between 0 and 50 (the cumulative sum of all eight individual human pressures), and the higher the HFP, the higher the human pressure. A full explanation of the HFP calculation is provided in the Supplementary Material .