Men Multiplied on the earth, but wickedness of man increase like anything, only evil thoughts are at the heart of men. violence and corruption as been increased. God had repented for making man on the earth, and decided to destroy him from the earth but he remembered family of Noah for their obedience towards God.
God asked Noah to prepare a ship to save himself and his family members and all kinds of living things on the earth from the flood of waters. God ordered rain on the earth for forty days and forty 
nights. Every living thing on the earth were
destroyed except the living things in the ship. After the waters abated off from the earth Noah and his family members along with all living things in the ship were came out. Noah build an altar and collected every clean animals and birds and offered burnt offerings on the altar. After that God though in his heart not to destroy the living things including men on the earth.
” God has abundant love towards his creation, he forgave all the exceeding of men and blessed them again. “
~ Genesis 7&8 Chapters