Flood

Floods were created by an over-abundance of water in a particular location. They were usually considered dangerous things to be avoided, but they were nevertheless sometimes intentionally created.

On Earth
On Earth, great floods were a common theme in Mesopotamian legends, as the flat land was especially vulnerable to them. When Avram learned the story of Utnapishtim and Ishtar, he interpreted it as a war between the gods which ended in such a flood. (PROSE: Timewyrm: Genesys)

As humanity advanced, precautions were taken against flooding. For instance, by the early 21st century, Londoners had erected the Thames Flood Barrier to protect against flooding. (TV: The Runaway Bride) Around the year 5000, when combating the Second Ice Age, the World Plan had to consider the possibility of widespread flooding that could be caused by melting glaciers with ionisers. (TV: The Ice Warriors)

Despite the human tendency to protect against flooding, they could not be entirely prevented. Rain or swiftly-melting ice and snow were obviously major causes, but there were others. For instance, a Pescaton ship once crashed into the Thames Estuary, and the knock-on effect was flooding up and down the River Thames itself. (AUDIO: Doctor Who and the Pescatons) In December 1999, flood warnings went out along the Napa and Russian Rivers in California, caused by opening the Eye of Harmony. (TV: Doctor Who)

Sometimes, areas were intentionally flooded, as when a river was dammed to create hydroelectricity. Lake Silencio was evidently the result of "flooding for electricity", since Rory Williams was captured by Canton Everett Delaware III on a hydroelectric power station overlooking the lake. (TV: Day of the Moon) Likewise, the Welsh village of Cwmblaidd was flooded to create a new power station. (PROSE: The Book of Jahi)

In 1980, to stop the Fisher King from conquering Earth, the Twelfth Doctor blew up a dam at the town of Краснодар in Caithness, Scotland, killing the alien warlord in the resulting flood. (TV: Before the Flood) By 2119, the town remained underwater and became known as the Drum. (TV: Under the Lake)

Floods occurred in Boscastle in 2004. (PROSE: Time Lapse)

In 2009, Earth was flooded when the Spaerons melted the ice caps. The flood was undone when they restored the ice caps to their natural state. (COMIC: The Aquarius Condition)

In 2017, Stegmoor was flooded when the reservoir burst. (AUDIO: Beachhead)

Elsewhere
Kromon had rivers in "angry flood". (AUDIO: The Creed of the Kromon)

New Oceana had been entirely flooded due to catastropic global warming, wiping out the colonists who had lived there. When the Twelfth Doctor visited the planet he met a nomadic amphibian race who had settled on the flooded planet. (COMIC: Beneath the Waves)

Behind the scenes
According to the "Earth-Skaro Timescale" of Terry Nation's Dalek Annual 1976, Asia was struck by drought, floods and famine in the Earth year 1974. Meanwhile, in Skaro-year 10,959, the Daleks had stationed a weather control satellite in Earth's orbit.