Key terms Flashcards
What is evaporation?
The process in which liquid water is transformed into water vapour, which is a gas. A large amount of energy is required for this to occur, which is usually provided by heat from the sun or by the movement of air.
What is evapotranspiration?
The total amount of moisture removed by evaporation and transpiration from a vegetated land surface. Transpiration is the process by which water is lost from a plant through stomata in its leaves.
What is Groundwater flow?
The slowest transfer of water within the drainage basin. It provides the main input of water into a river during drought or dry seasons. Groundwater flows at a steady rate though bands of sedimentary rock. It can take thousands of years for moisture that seeps into permeable rocks deep under the surface to be returned to the drainage basin hydrological cycle as groundwater flow.
What is infiltration?
The passage of water into the soil. infiltration take splice 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.
What is interception?
The process by which raindrops are prevented from directly reaching the soil surface. Leaves, stems, branches, herbaceous plants and grasses growing close to the surface all intercept water. Evaporation removes some of this moisture from the system and it does not reach the river as run off.
What is 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 igneous or metamorphic, are impermeable so there is no percolation or groundwater flow.
What is precipatation?
Water in any form that falls from the atmosphere to the surface of the earth. e.g. rain, snow, sleet and hail.
What is run off?
All the water that enters the river and eventually flows out of the drainage basin. It can be qualified by measuring the discharge of a river.
What is 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.
What is throughfall?
The water that drips off leaves during a rainstorm. It occurs when more water falls onto the interception layer of the tree canopy than can remain on the leaves.
What is throughflow?
The water that moves down-slope through the subsoil, pulled by gravity. It is particularly effective when underlying impermeable rock prevents percolation.
