A synonym starting with d of the word calamity is 'disaster'
intense, inflexible
Deluge
Disaster
disaster
Disaster?
"Disaster" is probably the closest synonym, but "distress" rather close.
One option is the word disaster.
The synonym for stern is strict or severe.
Dazzling is a synonym for beautiful. Delightful is another word for beautiful.
There are many synonyms of happiness like pleasure, satisfaction etc. One that starts with D letter is Delight.
severe, rigid, bitter, rough