Inundation

Inundation is the covering of land by water, usually resulting from the temporary or sustained overflow of bodies of water such as rivers, lakes, or seas. The term is commonly used in hydrology, geography, and disaster studies to describe land that has been submerged beyond its normal water level, whether by floods, storm surge, or extraordinary tides. Inundation can affect small areas or large regions and may be seasonal, episodic, or chronic depending on hydrological conditions and sea level.

Causes include river overflow during periods of heavy rainfall or rapid snowmelt; coastal storm surge and high tides; tsunamis; dam or levee failure; and sustained sea-level rise or extreme weather events. Human activities such as land-use change and urbanization can exacerbate inundation by reducing drainage and increasing runoff.

Common types are riverine inundation, where floodwaters inundate floodplains; coastal inundation, where water covers coastal land due to storm surge or high tides; and urban or pluvial inundation, where heavy rainfall overwhelms drainage systems.

Impacts range from damage to infrastructure, agriculture, and housing to public health risks and displacement. Ecological effects include sediment deposition, habitat change, and nutrient redistribution. Economic losses from business interruption are often substantial.

Management relies on hazard assessment, forecasting, and mitigation measures such as flood defenses, floodplain management, early warning systems, and urban drainage improvements. Restoring wetlands and restoring natural floodplains can also reduce risk.

Notable historical inundations include the 1953 North Sea flood affecting the Netherlands and the United Kingdom, and major flooding in China in 1931, among other events.