Essential River and Hydrology Terminology

Hydrological and Fluvial Terminology

• Evapotranspiration: The process by which water is transferred from the land to the atmosphere by evaporation from the soil and transpiration from plants.
• River: A large natural stream of water flowing in a channel to the sea, lake, or another river.
• Flood: An overflow of a large amount of water beyond its normal limits, especially over normally dry land.
• Permeable: Allows liquids or gases to pass through cracks or openings.
• Impermeable: Not allowing fluids or gases to pass through.
• V-shaped valley: A valley formed by flowing water or a river.
• Upstream: Moving or situated in the opposite direction to which a stream or river usually flows; nearer to the source.
• Downstream: Situated or moving in the direction in which a stream or river usually flows, towards the mouth.
• Waterfall: A cascade of water flowing from a height, formed when a river or stream flows over a steep incline or hill.
• Gorge: A narrow valley between hills or mountains, typically with steep rocky walls and a stream running through it.
• Natural hazard: An extreme event that occurs naturally and causes harm to humans.
• Floodplain: An area of low-lying ground next to a river, formed mainly of river sediments and subject to constant flooding.
• Alluvium: A deposit of clay, silt, and sand left by flowing floodwater in a river valley or delta, typically producing fertile soil.
• Meander: A winding, curving bend in a river.
• Contour line: A line on a map joining points of equal height above or below sea level.
• Relief: The difference between the highest and lowest elevations in an area.
• Delta: Land that forms at the mouth of a river. They form from the deposition of sediments carried by a river as the flow leaves its mouth.
• Braided channel: A channel that consists of a network of small channels separated by small or temporary islands called braid bars, aits, or eyots.
• Embankment: A wall or bank of earth or stone built to prevent a river from flooding an area.
• Discharge (River discharge): The volume of water flowing through a river channel.
• Hydrograph: A graph showing the rate of flow versus time past a specific point in a river.
• Peak flow: The maximum rate of discharge in a river or stream, often resulting from events like snowmelt or heavy precipitation.