浩 is extremely popular in Chinese male names (e.g. 浩然, 浩宇, 子浩). It conveys grandeur and strength. It also appears in literary compounds like 浩瀚 (vast) and 浩劫 (catastrophe).
氵 is the water radical 水 in left-side form. It places 浩 in the water family alongside 河海洋, hinting at vastness and flow, fitting for a word that came to mean grand and boundless.
告 (gào) supplies the sound, drifted in tone to hào in 浩. The same phonetic appears in 皓浩鹄, all sharing the gao/hao sound family. Faint semantic flavor of proclamation suits the imagery of vast announcing waters.
