Pronunciation /əʊvəˈwɛlm/
verb
[with object]
1 Bury or drown beneath a huge mass of something, especially water.
1.1 Give too much of something to; inundate.
2 Have a strong emotional effect on.
3 Defeat completely.
3.1 Be too strong for; overpower.
==========
Yesterday's heavy mid-day downpour overwhelmed storm drains causing many traffic headaches.

[I was interested to see that the word "whelm" is defined by Lexico: "to engulf, submerge, or bury." I don't recall ever hearing it. Of course, like several of the word encountered here, it is identified as archaic.]