Here "flow away" represents being taken away from him. Alternate translation: "his goods will be taken away from him, like goods that float away in a flood, on" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here "wrath" represents punishment. The abstract noun "wrath" can be expressed with the verb punish. Alternate translation: "the day when God punishes people" (See: [[rc://en/ta/man/translate/figs-metonymy]])