IPA: /ˌhaɪ.drəʊˈdʒiː.ə.lɪst/
KK: /haɪˌdroʊˈdʒiː.ə.lɪst/
A person who studies the distribution and movement of groundwater in the soil and rocks of the Earth's crust.
The hydrogeologist conducted tests to determine the water quality in the area.
Hydrogeologist → It is formed from "hydro-" (from Greek "hydor", meaning water) and "geologist" (from Greek "geōlogia", meaning study of the earth). The word refers to a scientist who studies the distribution and movement of groundwater in the earth.
Think of 'water' ('hydro-') and 'study of the earth' ('geologist') to remember that a hydrogeologist studies water in the earth.