What is the Roman Catholic position on literally reading the Flood account in Genesis?

Again the Church has no official position on whether it covered the whole earth http://www.newadvent.org/cathen/04702a.htm but since the Council of Trent declared Catholics must follow the unanimous consent of the Fathers, i think that we must believe that the Flood wiped out all humans except the 8 in the ark, some New Testament passages which talk about this seem to require the flood was anthropogenically universal. As to whether the flood covered the whole Earth the Fathers showed some reservations about this but it seems to have been the unanimous opinion of nearly everyone till the 17th century. BTW this source was written in 1917 I think.

Regarding the interpretation of the narratives in the book of Genesis, Roman Catholics are required to hold the following propositions:

• God created the universe ex nihilo a finite time ago. (This is consistent with current established sience as it can say nothing about the time before inflation.)

• God creates the spiritual soul of each human person ex nihilo at the moment of its infusion to that person's body, with that moment currently understood to be the time of conception.

• God started to create and infuse spiritual souls with two and only two human persons, a first man "biblical Adam" and a first woman "biblical Eve", and continued to do that with all patrilineal descendants of biblical Adam and only with them (except Jesus, Who according to his human nature is not a patrilineal descendant of biblical Adam or of any other man).

• As a corollary of the previous point, all past, present and future human persons, except for the first two, are patrilineal descendants from biblical Adam. (This is consistent with current genetic genealogy if biblical Adam is Y-Chromosomal Adam or a patrilineal ancestor thereof.)

• Biblical Adam and Eve were constituted in a state of grace at the moment of their creation and lost it by sinning, with that loss being propagated to all patrilineal descendants of biblical Adam, who are infused sanctifying grace only when the redemptive merits of Jesus Christ are applied to them (in the case of St. Mary, that application occurred at the moment of her creation).

Aside from the above propositions, Roman Catholics are free to understand any narrative in Genesis, as well as the narratives of the Exodus and of the conquest of Canaan, as wholly allegorical, wholly historically factual, or any point in between. On the other hand, they must hold the historical factuality of all events in the Gospels and in the Acts of the Apostles (where BTW Jesus' genealogies are not events but conceptual frameworks).

I will add a further precision to Jayarathina Madharasan's statement in his previous answer that "Careful attention must be paid to the actual meaning intended by the authors, in order to render a correct interpretation." While the statement is strictly true, it does not imply that the meaning intended by the OT authors is the meaning intended by God for Christians. This is an extremely important point, because Scripture's inerrant meaning is God's intended meaning, not the human author's intended meaning. The distinction between both intended meanings is specifically noted in the Catechism [1]:

109 In Sacred Scripture, God speaks to man in a human way. To interpret Scripture correctly, the reader must be attentive to what the human authors truly wanted to affirm, and to what God wanted to reveal to us by their words.

Thus Catholics have no problem whatsoever with the fact that when the human author of Psalm 137 called blessed the one who would seize and dash Babylon's babies against the rock he really meant exactly that, because the inerrant meaning of any OT passage is God's intended meaning for Christians, not the human author's intended meaning for his contemporary readers, and God's intended meaning of any OT passage for Christians is known only when the passage is read in Christ and from Christ and for the purpose for which it was written, which is to teach the truth which is relevant to our salvation (1 Cor 10:11; 2 Tim 3:15-17) and not to teach natural science, profane history, or other forms of merely worldly knowledge for their own sakes.

At this point someone might object that Jesus spoke of OT figures such as Noah as if they had been historically factual. To which I respond that whenever Jesus did that, He did it for the sake of stating an important point for the spiritual life, not for the sake of stating the historical factuality of the OT figures themselves.

[1] http://www.vatican.va/archive/ENG0015/__PQ.HTM

The Flood certainly occurred, else St. Peter would have been referring to a fiction when he wrote:

1 Pet. 3:20
…in the days of Noe, when the ark was a building: wherein a few, that is, eight souls, were saved by water.

2 Pet. 2:5
And spared not the original world, but preserved Noe, the eighth person, the preacher of justice, bringing in the flood upon the world of the ungodly.

cf. Sacræ Theologiæ Summa IB: Church of Christ, Holy Scripture p. 662, On the Absolute Truth of Holy Scripture, § 181. "Notes for the Solution of the 'Biblical Question'"