Hydrological Glossary

  • Abstraction: Collecting water from the natural sources for human use

  • Afforestation: Establishment of a forest or a stand of trees in an area where there was no recent tree cover

  • Altitude: Height of a point in relation to sea or ground level

  • Aquifers: Underground layer of water-bearing materials

  • Biosphere: Thin layer of Earth that supports life

  • Channel flow: Takes over as soon as the water enters a river or channel

  • Cryosphere: Areas on the Earth where water exists in frozen form e.g Glaciers

  • Deforestation: Large-scale removal or clearing of forests

  • Discharge: Into another drainage basin

  • Drainage Basin: The area drained by its river and tributaries

  • Evaporation: moisture is lost directly into the atmosphere from water surfaces

  • Ferrel Cell: Atmosphere cell in which cool air sinks

  • Flood plain: An area of low lying ground adjacent to a river which is subject to flooding

  • Groundwater flow: Slow transfer of percolated water through the permeable rocks

  • Hadley cell: Atmosphere cell in which warm air rises at equator

  • Impermeable: Not allowing liquids through it

  • Infiltration: Water is absorbed by the soil

  • Inputs: Materials flowing into a system

  • Interception: The retention of water by plants and soils which is evaporated from the vegetation

  • Irrigation: Artificially watering soil to assist growing crops

  • Monoculture: One culture

  • Network: The streams in a drainage basin

  • Outputs: Materials that flow out of a system

  • Percentage contribution: The relative importance and size

  • Percolation: A deeper transfer of water downslope through the soil

  • Permeable: Allowing liquids to go through

  • Polar Cell: Cool air sinking and spreads to lower latitudes

  • Precipitation: Liquid (rainfall) that falls back onto Earth

  • Soil Moisture recharge: Water moves downward from surface when precipitation of greater than evapotranspiration

  • Soil moisture surplus: Precipitation exceeds potential evapotranspiration

  • Soil moisture utilisation: Evapotranspiration exceeds precipitation as water is transferred as throughflow to the river

  • Surface runoff: The movement of water that is unconfined by a channel across the surface of the ground

  • Throughflow: the lateral transfer of water downslope through the soil

  • Transpiration: water is lost from plants through minute pores and transferred to the atmosphere. 

  • Urbanisation: More people moving into urban areas than rural areas

  • Water budget: Annual balance between precipitation, evapotranspiration and runoff

  • Watershed: Boundary of drainage basins

  • Zone of saturation: Water cannot go through this area