This article is about water-related disasters other than drought. All of these natural events pose significant challenges to fantasy medieval societies, both from the wreckage they cause to the long-term effects when water sweeps through an area, possibly bringing monsters and disease.
Water disasters can cause thousands of drowning deaths, interfere with trade, destroy agriculture, and ultimately contribute to the fall of empires. Your player characters will be quite busy in a campaign world that suffers even a few of these.
Permanent Alterations in Geography
There are the rarest, and largest, water disasters, resulting in permanent changes to large-scale geography.
- Sea Level Change: Sea level changes aren’t simply the water rising on coastal settlements, although that’s certainly a possibility. Rising water levels can submerge seaports and cause islands to disappear. But it also encompasses ice ages (including “little ice ages“), which can melt, revealing ground beneath (and sometimes, eldritch civilizations) or freeze, turning city rivers to ice.
- River Course Shifts: For societies that rely on rivers as a source of energy and food, a river shifting course can devastating. Cultures without irrigation can disappear as a result. Rome’s seaport in ancient times, Ostia, is now three kilometers from the Mediterranean owing to silt and sea change. The Yellow River in China shifted as much as 300 miles, sometimes reaching the ocean to the north of Shandong Peninsula and sometimes to the south.
- Lake and Bays: Large bodies of water that are dammed up due to ice can melt, flooding plains and altering the terrain. Woe betide any society in the basin. Lake Anasazi, a gigantic lake in North America, finally released when ice dam melted, flooding vast tracts. This happened several times.
Temporary Alterations in Geography
Temporary alterations to geography tend to happen much more quickly and thus can inflict significant damage over a very short period of time, sometimes in a matter of minutes.
- Flood: The most commonly-associated water-related event, floods occur from “too much” rain too fast. This may be from severe weather such as hurricanes. The Huang He floods collectively killed millions of people and considered among the deadliest natural disasters ever recorded.
- Tsunami: Tsunami are caused by earthquake, volcanic eruption, even (locally) a huge landslide. One of the latter can result in a tsunami hundreds of feet high in a fiord. The deadliest tsunami happened in our lifetime, reached over 100 feet high, and killed over 200,000 people. Hurricane, Typhoons, and Cyclones: Essentially the same thing, hurricanes happen in the North Atlantic/Northeast Pacific, typhoons in the Northwest Pacific, and cyclones in the South Pacific/Indian Ocean. Thanks to technology, hurricanes can be predicted; a fantasy society may have no such protections. Prior to modern forecasting, hurricanes killed over 10,000 people. Cyclones and typhoons have killed over half a million people.
- Dam Failure: Not surprisingly, civilized societies due their best to curb the effects of water on land, both to harness its power and control its flow. Sometimes, Nature wins. Because dams are typically long-lasting and towns rely on it for water power, they are particularly vulnerable. One dam that broke killed over 170,000 people and displaced 11 million.
Water will likely shape the course of your fantasy world’s history, be it falling from the air or on surging on the ground. It is one of nature’s most powerful elements, and fantasy societies do well to respect it. Those who underestimate it may be washed away.
Your Turn: Have water disasters played a part in the history of your world?
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