IPA: /haɪˈdrɒlədʒɪkli/
KK: /haɪˈdrɑlədʒɪkli/
In a way that relates to the study of water and its movement on Earth.
The river flows hydrologically, affecting the surrounding ecosystem.
Hydrologically → It is formed from "hydro-" (from Greek "hudor", meaning water) and "-logically" (from Greek "logia", meaning study or science). The word refers to the scientific study of water and its properties.
Think of 'water' ('hydro-') being studied ('-logically') — that's why hydrologically relates to the study of water.