Please find below the link to a list of important websites and mailing lists to keep up to date with various academic positions (graduate and postdoc opportunities + tenure track jobs) in hydrology and in general earth sciences. We hope it helps! Thanks to Harsh Beria (from the Hydrology Section Student Subcommittee of the American Geophysical Union, AGU H3S)  for compiling such an exhaustive resource!
https://docs.google.com/document/d/1c2k1RV7mogsFAMDOHufciYI65Vi0Sg9rWxdfpxXPJQc/edit