1. To drive oil through a reservoir by injecting water or another fluid under pressure into the reservoir formation. 2. To drown out a well with water. 3. To make the velocity the same everywhere below some given surface as a step in depth-migrating data; see depth-migration. For example, in migrating subsalt data, one often assumes that the sediment velocity function applies everywhere (sediment velocity flood) while migrating the top of the salt, then assumes salt velocity everywhere below the top salt (salt flood) to migrate the base of the salt, and finally one assumes a sediment velocity function below the base salt. Hopefully produces a clear sharp image of subsalt reflections.