On this day, the bottom of Noah's ark, submerged 11 cubits beneath the water's surface, touched down and came to rest on the top of Mount Ararat.
(This follows the opinion of the Talmudic sage Rabbi Joshua, who maintains that the Flood began on Iyar 17.)
See: Great Flood Begins.
"Pulver Purim" was established by Rabbi Avraham Danzig (1748-1820) author of the halachic works Chayei Adam and Chochmat Adam, after he and his family were miraculously saved from a fire on the eve of the 16th of Kislev.
The inferno engulfed many homes, including his own home and the very room where all of his family members were, causing some of the walls to collapse. Rabbi Avraham Danzig then established the 16th of Kislev as a day of celebration for all of his future descendents.
Noah was a tzadik, a very great man. He saved the entire world. But he didn't approach Abraham's greatness.
When G‑d told Noah to build an ark before the world would be destroyed, Noah built an ark.
But when G‑d told Abraham He was about to destroy the cities of Sodom and Gomorrah—cities corrupt and evil to the core—Abraham argued. He said, “Perhaps there are righteous people there! Will the Judge of All the Earth not do justice?”
Where Noah donned a warm coat for himself and his family, Abraham built a warm fire for the entire world.
Because Abraham felt a sense of ownership for the world in which he lived. If there was something wrong, it needed to be changed. Even if it had been decreed by the will of G‑d.