The Water Cycle (Unit 1, Topic 2) Flashcards
Global distribution and size of major stores of water- lithosphere, hydrosphere, cryosphere and atmosphere. Flows and transfers within systems, drainage basin as open systems, water balance. Runoff variation and flood hydrograph. Changes in the water cycle including natural variation, water abstraction and land use change.
What are the four spheres of water stores?
Lithosphere- Water in rock
Cryosphere- Water in ice
Biosphere- Water in organic matter
Atmosphere- Water in the air
What is the definition of a Drainage Basin?
An area that is drained by a river system or tributaries
What is a Water Shed?
Water Shed- An area or ridge of land that separates waters flowing to different rivers, basins, or seas.
What is a Tributary?
A river or stream flowing into a larger river or lake
What is a Confluence?
The junction of two rivers, especially rivers of approximately equal width
What is a Source?
A body or process by which energy or a particular component enters a system
What is a Flood Plain?
An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
What is the Mouth?
The place where a river enters a lake, larger river, or the ocean is called its mouth.
What are the inputs of water into a drainage basin?
The precipitation by clouds causes the biggest input into the drainage basin
What are the outputs of a drainage basin?
Interception into the ground causes less water to move via surface runoff meaning it is a slower output of the drainage basin
Evapotranspiration causes intercepted or pools of water to be evaporated back into the atmosphere
Surface runoff causes large volumes of water to create routes in the drainage basin forming streams of rivers when it rains that make its way towards the mouth of the drainage basin
What is the equation for Discharge
Cross Sectional Area(m2) x velocity(m/s)
What is the equation for Cross Sectional Area?
Width x Mean Depth (m)
What is latent heat?
Latent heat is the stored thermal energy in the environment that is taken in by water molecules from the surrounding environment in order to break its hydrogen bonds and evaporate.
How do Clouds form?
Dust or pollen act as a nuclei that water condenses on and this gathers together with other nuclei to form clouds
How is Precipitation Caused by Rising Warm Air?
Warm air is less dense, when they meet the warm air rises, this makes it cool so it condenses, attaching itself to pollen nuclei in clouds, causing frontal precipitation
What is topography?
When warm air meets mountains and is forced to rise and cool, condensing water molecules. Creating topographic precipitation.
What are convections?
Sun heats up the ground causing evaporation, it the gas goes higher and condenses it causes convection precipitation
What are the characteristic’s of a flashy hydrograph?
Shorter lag time, so increase peak discharge.
Greater rising and falling limb.
More likely to flood areas surrounding the river
What are the characteristic’s of a subdued hydrograph?
Longer lag time causing a decreased peak discharge
Low rising and falling limb
Less likely to break its banks and cause flooding
What is the water balance equation?
Precipitation=total overland head flow + evapotranspiration and storage
P= O+ES
What is water surplus?
Occurs when there is larger input into the river system than there is output
What is water deficit?
When the water demand exceeds the supply
What are the physical factors affecting the Water Cycle?
Precipitation and storms- Intense storms generate more precipitation and greater peak discharge. This increases flow size and surface run-off as soil saturates quicker.
Seasonal Changes- Temperatures in winter reach 0c causing water to freeze regularly, reducing input into river basins. Plants also have seasonal changes as the leaves on some plants will rot over the winter, depending on the time of year this could increase or decrease interception.
Vegetation intercepts rainwater and slows its movements to the river channel. Interception at its highest like in a deciduous forest decreases surface run off and peak discharge
What are the human factors affecting the Water Cycle?
Farming practices- Ploughing breaks up the soil so that more water can infiltrate the ground, crops will increase their infiltration and interception. Evapotranspiration increases, livestock increases surface runoff as they make the ground softer.
Land use - Construction of new buildings and roads creates impermeable surfaces, preventing infiltration but significantly increasing surface runoff making flooding more likely
Deforestation- this reduces interception by vegetation, dead plant material helps to hold the water allowing for infiltration rather than surface runoff. When forest cover is removed the rate of infiltration decreases.
Water Abstraction- More water is taken for areas with high population density this reduces the volume of water in the stores such as lakes and rivers. In dry season even more is taken for irrigation and consumption.
