Drainage and promotion in the context of online marketing or business can be referred to as traffic diversion and promotion、However, this is not a standard term in English、A more commonly used phrase might be traffic redirection and promotion or simply traffic diversion for promotion、If you have a specific context or industry in mind, please provide more details so I can give a more accurate translation or equivalent expression、

For instance:
Traffic Diversion:引流 (yǐn liú)
Promotion: 推广 (tuī guǎng)

In English, it could be translated as Traffic Diversion for Promotion or Redirecting Traffic for Promotion、

If you're referring to a different concept, please clarify!