Drainage Basin Hydrological Cycle Flashcards
Define transpiration
The transport of water through an actual, vegetated plant into the atmosphere.
Define evaporation
The process by which liquid water is transformed into water vapour, which is a gas. A large amount of energy is required for this to occur. The energy is usually provided by heat from the sun or by the movement of air (wind).
Define interception
The process by which raindrops are prevented from directly reaching the soil surface. Leaves, stems and branches on trees, and herbaceous plants and grasses growing close to the surface, intercept water. Evaporation removes some of this moisture from the system and it does not reach the water as run off.
Define through flow
The water that moves down-slope through the subsoil, pulled by gravity. It is particularly effective when underlying impermeable rock prevents percolation.
Define stemflow
The water that runs down the stems and branches of plants and trees during and after rain to reach the ground. It takes place after interception has occurred.
Define surface storage
Part of precipitation retained on ground surface.
Define precipitation
Water in any form that falls from the atmosphere to the surface of the Earth. It includes rain, snow, sleet and hail.
Define overland flow
When water flows over the surface due to impermeable or frozen ground.
Define vegetation storage
Water stored in vegetation.
Define infiltration
The passage of water into the soil. Infiltration takes place relatively quickly at the beginning of a storm, but as the soil becomes saturated the infiltration rate falls rapidly. Infiltration rates are affected by the nature of the soil itself. Sandy soils let more water pass through than clay soils.
Define soil water storage
The water stored in soil.
Define throughflow
The water that moves downslope through the subsoil, pulled by gravity. It is particularly effective when underlying impermeable rock prevents percolation.
Define channel storage
A volume of water in a channel (river of stream).
Define percolation
The downward movement of water within the rock under the soil surface. The rate of percolation depends on the nature of the rock. Some rocks, particularly those of an igneous or metamorphic nature, are impermeable so there is no percolation or groundwater flow.
Define groundwater storage
Water that is stored in the ground.