The Water Cycle Flashcards
Precipitation
The input into a drainage basin system. It includes all forms of moisture entering: hail, snow, dew, frost, sleet and rain.
Interception
The storage of water when it lands on vegetation (or structures like buildings) before it reaches the soil. It is a temporary store before evaporation or stemflow
Surface storage
storage of water on the surface including puddles, ponds and lakes
Soil moisture
The storage of water in soil. Water is held in the small gaps between soil particles
Groundwater storage
The storage of water in the ground rocks of permeable rock. The water is held in cracks (limestone) bedding planes (sedimentary rock) or pores (chalk). Rocks with lots of water storage are called aquifers
Channel storage
The storage of water in the river channel. As water is being transported to the sea it is a store of water
Vegetation storage
The storage of water in the vegetation. Plants and trees take up water through their roots and water is stored here.
Surface runoff/overland flow
The horizontal flow of water over the surface of the land either in little channels or over the whole surface – this is usually a quick flow.
Stem flow
The downwards flow of water moving downwards from interception storage to the surface
Throughfall
The downwards movement of water as it drips from one leaf to another
Throughflow
The horizontal flow of water moving through soil (between the particles) towards the river
Interflow
The horizontal movement of water through rock above the water table. (Below water table is groundwater flow)
Infiltration
The downwards movement of water from the surface into the soil.
Percolation
The downwards movement of water from the soil to the permeable ground rock
Groundwater flow
The horizontal movement of water through the rocks below the water table
Baseflow
Groundwater flow that feeds into rivers
Channel flow
The movement of water in the river channel moving towards the sea.
Evaporation
The output of water when water is heated and turned from a liquid into a gas. Rates are affected by temperature, wind, humidity, and water availability
Transpiration
The output of water where moisture is taken into plants through their roots, moved to the leaves by capillary action and then evaporates from the leaves into a gas.
Evapotranspiration
The combined output of water from evaporation and transpiration. Potential evapotranspiration is the amount that could occur if water were available. Actual evapotranspiration is the amount that actually occurs. Eg deserts have a very high potential evapotranspiration due to the high temperature however actual evapotranspiration is low as there is very little water available.
Condensation
Transfer of water from a gaseous state to a liquid state, for example, the formation of clouds
Condensation nuclei
Microscopic particles on which water vapor condenses to form cloud droplets – eg dust or smoke
Dew point
The temperature at which the water vapor in the air becomes saturated and
condensation begins.
Sublimation
Transfer from a solid state (ice) to a gaseous state (water vapour)
Deposition
Transfer from a gaseous state (water vapour) to a solid state (ice) – eg hoar frost
Latent heat
The heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.
Discharge
The output of water from a river channel out to sea.
Aquifer
A vast underground reservoir most commonly formed in rocks such as chalk and sandstone
Impermeable surface
Does not allow water to pass through
Permeable surface
Allows water to pass through
Urbanisation
The increasing proportion of people living in towns and cities as opposed to the countryside, leading to the replacement of vegetated ground with impermeable concrete and tarmac
Deforestation
The removal of trees, leading to surface runoff and soil erosion and reducing soil water stores
Drainage basin
The area of land that is drained by a river and its tributaries
Source
The point where the river begins. The river is both narrow and shallow here, discharge is low.
Mouth
The point where the river meets the sea. The river is wide and deep here, and discharge is high.
Watershed
The edge of a drainage basin
Tributary
Smaller rivers that feed into the main channel
Confluence
The point where two rivers meet
Flood (storm) hydrograph
A graph showing the discharge of a river following a particular storm event
Lag time
Time between peak rainfall and peak discharge. Longer lag time = less likely to cause a flood
River regime
The pattern of discharge over the course of a year. Affected by geology, vegetation, urbanisation, size/shape of drainage basin, rainfall intensity etc.
Soil moisture (water) budget
Describes the changes in the soil water store during the course of a year. It is determined by precipitation and evapotranspiration. There are several stages in a soil moisture budget graph including: Soil moisture utilisation; Soil moisture deficit; Soil moisture recharge; Field capacity; Soil moisture surplus.
Soil moisture utilisation
The extraction of soil moisture by plants for their needs; efficiency of withdrawal decreases as the soil-moisture storage is reduced.
Soil moisture deficit
The point at which soil moisture falls below field capacity - caused by a lack of precipitation and large amounts of evapotranspiration
Soil moisture recharge
Following soil moisture deficit, precipitation is greater than potential evapotranspiration moisture will be added to the soil.
Field capacity
The point at which soil becomes saturated.
Soil moisture surplus
The period when soil is saturated and water cannot enter, and so flows over the surface – caused by low levels of evapotranspiration and high levels of precipitation
Soil porosity
Pores or spaces in the soil. The greater pores or spaces, the greater the water holding ability.
Water balance
An equation used to express the relationship between the main water stores – the lithosphere, the hydrosphere, the cryosphere and the atmosphere
Hillslope system
The way in which water moves down a typical hillslope towards a river, involving stores and transfers
Irrigation
The supply of water to the land by means of channels, streams and sprinklers in order to permit the growth of crops
Water table
The upper level of saturated rock
Water abstraction
The extraction of water from rivers or groundwater aquifers
Saltwater intrusion
The movement of saltwater into an aquifer, which may cause contamination. Often caused by over abstraction of groundwater from an aquifer.
Relief/Orographic rainfall
Rainfall formed due to warm moist air being forced to rise by the relief of the land. Once risen, the air cools and condenses forming rain.
Frontal rainfall
Rainfall formed when warm air meets cold air. Warm air is less dense and therefore rises above the cold air, cooling, condensing and forming rain.
Convectional rainfall
Rainfall formed when heat from the sun heats the ground. The warm ground heats the air above causing it to rise, cool, condense and form rain.
Ablation
Outputs from a glacial system due to melting (size of glacier decreases)
Accumulation
Inputs to a glacial system due to snowfall (builds a glacier)
