In my opinion there is adequate evidence. For archaeological evidence, the same question asked on the internet will give you more information than I can supply.
In addition a flood story occurs in many ancient accounts which although embellished with fanciful fabrications would point to an event common to all.
The Bible stands or falls by its integrity. From a Biblical point of view if the flood did not take place then the gospel of Jesus Christ and the kingdom of God cannot be trusted and forms no basis for hope of eternal life.
The Bible claims to be written by inspiration of God.
2 Timothy 3:16 All scripture is given by inspiration of God...
2 Peter 1:21 holy men of God spake as they were moved by the Holy Spirit.
John 10:35 the scripture cannot be broken;
The Bible, besides giving the factual account of the flood (free of the superstitious nonsense that appears in other ancient accounts), also refers to Noah and the flood elsewhere as follows:
1 Chronicles 1:4 Noah, Shem, Ham, and Japheth.
Isaiah 54:9 For this is as the waters of Noah unto me: for as I have sworn that the waters of Noah should no more go over the earth; so have I sworn that I would not be wroth with thee, nor rebuke thee.
Ezekiel 14:14 Though these three men, Noah, Daniel, and Job, were in it, they should deliver but their own souls by their righteousness, saith the Lord GOD.
Ezekiel 14:20 Though Noah, Daniel, and Job, were in it, as I live, saith the Lord GOD, they shall deliver neither son nor daughter; they shall but deliver their own souls by their righteousness.
The Bible also explains how the earth was divided up between the offspring of the three sons of Noah (Genesis 10), many of the place names still exist today. The prophecies in Ezekiel use the Genesis place names so that we can locate the modern nations which occupy the lands (Ezekiel 39 and 40). If Noah and the flood is fiction the origins of the nations must also be; and the Jews could not be ‘Semites’ (descendents of Shem).
In the New Testament, Noah and Shem appear in the genealogy of Christ.
Luke 3:36... which was the son of Sem, which was the son of Noe, which was the son of Lamech,
The writer to the Hebrews speaks of the account of Noah and the flood as factual:
Hebrews 11:7 By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house; by the which he condemned the world, and became heir of the righteousness which is by faith.
So does Peter:
1 Peter 3:20 Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
2 Peter 2:5 And spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly;
2 Peter 3:5 For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water: 6 Whereby the world that then was, being overflowed with water, perished:
Jesus Christ, upon whose truthfulness, sinlessness, self-sacrifice and resurrection our hope of salvation is based, spoke of Noah and the flood as being factual. He used it to show how the world will be similarly unprepared for his return to rule this world in righteousness.
Matthew 24:38 For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, 39 And knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.
Luke 17:27 They did eat, they drank, they married wives, they were given in marriage, until the day that Noe entered into the ark, and the flood came, and destroyed them all. 30 Even thus shall it be in the day when the Son of man is revealed.
The return of Christ will certainly happen.
Acts 17:31... (God) hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead.
To reject the truthfulness of the account of the flood is to reject the Bible as the word of God and render belief in scripture useless for salvation.
I hope you have found this helpful.
May God bless you,