Water Cycle & DBs & Systems Flashcards
What is water stored as?
Liquid, Solid & Gas
Is most of the water in the ocean saline or freshwater?
Saline
How much of the water is freshwater?
3%
How much of the freshwater is frozen?
69%
What does water must be for humans?
Economically and physically accessible
What is it called when water is cycled between different stores?
The global hydrological cycle
What system is the GHC?
Closed system
What varies overtime in stores?
Magnitude
What does the magnitude of water depend on?
The amount of water flowing between the stores
What is evaporation?
When liquid water changes state into a gas, becoming water vapour
What does evaporation increase?
The amount of water stored into the atmosphere
When does condensation occur?
When water vapour changes state to become a liquid
What do water droplets do?
Can stay in the atmosphere or flow to other subsystems
Describe one change that can cause water vapour to condense
Temperature - large or rapid drop
What 2 things are essential for the water cycle?
Cloud formation & Precipitation
How do clouds form?
When warm air cools down, causing the water vapour in it to condense into water droplets
What 3 things that cause warm air to cool leading to precipitation?
Other air masses
Topography
Convection
How does other air masses lead to precipitation?
Warm air is less dense than cool air.
When they meet, warm air is forced above the cool air.
Cools down as it rises.
How does topography lead to precipitation?
When warm air meets mountains.
Forced to rise, causing it to cool.
How does convection lead to precipitation?
When the sun heats up the ground. Moisture on ground evaporates & rises up
. As it gets higher, it cools.
When does cloud formation and precipitation happen?
It varies seasonally.
What 2 cyrospheric processes change the amount of water stored as ice in the cyrosphere?
Accumulation & Ablation
What does the balance of accumulation and ablation vary with?
Temperature
When do variations in cyrospheric processes happen?
Over different timescales
Outline the impact of long-term global temperature changes on the water cycle.
(4 marks)
Higher temps cause the rate of evaporation to increase.
Means that more water is transferred from stores on the ground surface to the atmosphere.
As a result, more water is available for condensation and precipitation.
During periods of higher global temps, transfers between stores are therefore faster.
What do hydrographs show?
River discharge over a period of time
What is river discharge?
The volume of water that flows in a river per second
What is river discharge measured in?
Cumecs
What increases the discharge?
High levels of runoff
What is peak discharge?
The highest point on the graph when the discharge is the greatest.
What is lag time?
The delay between peak rainfall and peak discharge.
Why does lag time happen?
Because it takes time for the rainwater to flow into the river.
What does a shorter lag time increase & why?
River discharge because more water reaches the river during a shorter period of time.
What is a rising limb?
The part of the graph up to peak discharge.
What is a falling limb?
This is the part of the graph after peak discharge.
What are the 4 factors that affect runoff and hydrograph shape?
Size of drainage basin
Shape of drainage basin
Ground steepness
Rock and soil type
What does a larger drainage basin have compared to a smaller drainage basin?
L - More precipitation - higher peak discharge.
S - Shorter lag time so precipitation has less distance to travel to main channel.
What kind of a hydrograph does a circular basin have?
Flashy
Why is runoff higher when the water has less time to infiltrate?
Because it has a higher gradient
What are the physical factors that causes the water cycle to vary?
Seasonal changes and vegetation
What varies in inputs, stores and flows with the seasons?
The size.
Why does the size of flows through drainage basins reduce during the winter?
Because the water freezes.
What happens to the flows through drainage basins and outputs when the ice melts?
Size increases.
What does vegetation intercept and slow?
Precipitation and slows its movement into the river channel.
When is interception the highest?
When there is loads of vegetation and decidious trees have their leaves.
When there is more vegetation in a drainage basin, what is lost and through what?
Water through transpiration and evaporation.
What does lost water due to high amounts of vegetation reduce?
Runoff and peak discharge
What human activities affect the size of stores in the WC and the size and speed of flows?
Farming practices
Land Use Change
Water Abstraction
What is inflitration?
When rain hits the surface and what can’t infiltrate runs off.
What 4 farming practices can affect infiltration?
Ploughing
Crops
Livestock
Irrigation
How does ploughing affect infiltration?
It breaks up the surface so that more water can infiltrate, reducing the amount of runoff.
How do crops increase infiltration and interception compared to bare ground?
It reduces runoff.
What does livestock do to infiltration and runoff?
Decreases infiltration and increases runoff
What does irrigation do to runoff and what can fall if water is extracted for irrigation?
Increases runoff and groundwater or river levels can fall.
What does deforestation reduce?
The amount of water that is intercepted by vegetation, increasing the amount of water that lands on the surface.
What on the forest floor helps to hold the water which allows it to infiltrate and not run-off?
Dead plant material.
What happens when forest cover is removed?
Amount of infiltration will decrease.
What does construction of new buildings and roads create?
An impermeable layer over the land.
What does a impermeable layer prevent?
Infiltration
Why does urbanisation increase runoff?
Smooth surfaces
Why is water abstracted from stores?
To meet demand in areas where population density is high.
What does water abstraction reduce?
The amount of water in stores for example in lakes etc
Why is water abstracted more in dry seasons?
For consumption and irrigation.
Give 3 factors that affects the amount of run-off in a drainage basin.
Size of drainage basin
Shape of drainage basin
Gradient
What system are drainage basins?
A open system with inputs and outputs.
What is a river’s drainage basin?
The area surrounding the river where the rain is falling on the land flows into the river.
What else can a drainage basin be called?
A river catchment.
What is the boundary of a drainage basin?
The watershed.
What does water come in as in a drainage basin?
Precipitation.
What does water leave as in a drainage basin?
Transpiration and evaporation.
What are the inputs of a drainage basin?
Precipitation
What is the 6 parts of storage of a drainage basin?
Interception
Vegetation storage
Soil storage
Groundwater storage
Surface storage
Channel storage
What is interception?
When some precipitation lands on vegetation or urban buildings before it reaches the soil.
What does interception create?
A significant store of water in wooded areas.
What is vegetation storage?
Water that’s been taken up by plants.
What is surface storage?
Water in puddles, ponds, lakes
What is soil storage?
Moisture in the soil
What is groundwater storage?
The water stored in the ground, in the soil or in rocks.
What is the water table?
The top surface of the zone of saturation - the zone where all pores of soil or rock are full.
What is channel storage?
The water held in a river or a stream channel.
What are 5 flows of a drainage basin?
Infiltration
Throughfall
Stemflow
Throughflow
Percolation
What is infiltration?
Water soaking into the soil.
What is overland flow?
Water flowing over the land.
What is throughfall?
Water dripping from one leaf to another.
What is stemflow?
Water running down a stem or a tree trunk.
What is throughflow?
Water moving slowly downhill through the soil.
What is percolation?
Water seeping down through the soil into the water table.
What is groundwater flow?
Water flowing slowly below the water table through permeable rock.
What is baseflow?
Groundwater flow that feeds into rivers through river banks and river beds.
What is interflow?
Water flowing downhill through permeable rock above the water table.
What is channel flow?
The water flowing into the river or channel itself.
What are the 4 outputs of a drainage basin?
Evaporation
Transpiration
Evapotranspiration
River discharge
What is transpiration?
Evaporation within leaves
What is evapotranspiration?
The process of evaporation and transpiration together.
What is the water balance?
The balance between inputs and outputs.
What does the water balance affect?
How much water is stored in the basin.
What creates a water surplus?
When precipitation exceeds evapotranspiration in wet seasons.
What happens in drier seasons in the water balance?
Ground stores are depleted due to more evapotranspiration than precipitation.
What is potential evapotranspiration?
The amount of water that could be lost through evapotranspiration.
What is actual evapotranspiration?
What actually happens.
What do systems compose of?
Inputs, Outputs, Flows, Stores & Boundaries
What is a open system?
A open system is when systems receive inputs and transfer energy or matter with other systems
What is a closed system?
When energy inputs equal outputs - can occur across the boundary
What is dynamic equilibrium in a system?
When inputs equal outputs despite changing conditions
What is positive feedback and when does it occur?
When a chain of events amplifies the impacts of the original event
What is negative feedback and when does it occur?
Refers to a chain of events that nullifies the impacts of the original event leading to dynamic equilibrium
On a local scale is the carbon and water cycles a open or closed system?
Open
On a global scale is the water and carbon cycle a open or closed system?
Closed
What do inputs, outputs, flows and stores drive and cause overtime?
Changes in the water cycle!
What is an input?
Where matter or energy is added to the system
What is an output?
Where matter or energy leaves the system
What are stores?
Where matter or energy builds up in the system
What are flows?
Where matter or energy moves in the system
What are boundaries? Example?
Limits to the system e.g watershed
List 3 Inputs linking to precipitation?
Conventional, Relief, Frontal
What is precipitation? 3 Examples?
Any water that falls to the surface of the earth from the atmosphere. Snow, Hail & Rain
What is conventional precipitation ?
When warm air rises due to heating by the sun and it condenses at higher altitudes and falls as rain
What is relief precipitation?
When warm air is forced upward by a barrier such as mountains which causes it to condense at higher altitudes and fall as rain
What is frontal precipitation?
When warm air rises over cool air and when 2 bodies of air at different temperatures meet because warm air is less dense and lighter and it condenses at higher altitudes and falls as rain.
What does the infiltration capacity depend on?
How quickly infiltration occurs
What does the percolation rate depend on?
On the fractures that may be present in the rock and the permeability
What does the speed of through flow depend on?
The type of soil
What is the water balance used to express the process of ?
Water storage and transfer in the drainage basin system
What is an example of positive feedback loop?
Increased temperature changes ice to melt so reduces albedo effect and this causes more sun to be absorbed which increased temperature
What is an example of negative feedback loop?
High precipitation causes increased overland flow and evaporation which leads to more water in the aquafier store
What are tipping points?
When a large and irreversible change in the state of an environmental system occurs
What is an example of a tipping point?
Melting of ice in Greenland and Antarctic
Why is the CO2 levels in oceans lifted?
CO2 dissolves to form a weak acid
What is cyrospheric water?
Water stored as ice
What are the 5 types of cyrosphere water?
Sea ice
Ice sheets
Ice Caps
Glaciers
Permafrost
What is groundwater?
Water underground in the pore spaces of rock
What is the level at which pore space is completely saturated with water called?
Water table
What is terrestrial water?
Rivers and lakes
What is biological water?
Water stored in biomass especially plants
What is atmospheric water?
Water vapour
What holds more vapour warm or cold air?
Warm air
When do clouds form?
When water vapour condenses into droplets of water suspended in the atmosphere
What 3 human factors affect water store size?
Diversion of rivers
Abstraction of groundwater
Increase in population and demand
What are 3 natural factors that affect water store size?
Evaporation
Sea level changes
Ice ages/ice volume
How does the cyrosphere’s water levels increase and decrease?
Ice expands by colder temperatures causing more ice locked away at poles and this contracts by increased temperatures and this causes melting of ice which releases co2
What is an example of a local drainage basin?
River Ouse
What is the soil moisture budget?
The relationship between precipitation, evapotranspiration and soil water storage
What are 2 advantages of soil drainage?
Soil is improved, making it easier to plough and plant allowing roots to travel faster and further
Increased aeration of soil, allowing microorganisms to thrive, therefore breaking down organic matter to make nutrients
What are 2 dis-advantages of soil drainage?
Water gets into rivers much faster, leading to increased river flow and flooding
Soil can become dry and subject to soil erosion
How much of the rainforest has been lost in the last 50 years as a percentage?
20%
What is the water cycle like in the rainforest?
Very heavy precipitation but most of the rain is intercepted by vegetation or evaporated or taken back by trees and released through transpiration
What is the soil moisture like?
Very little water reaches the soil so moisture content is low and throughflow is minor
How much of the water in the UK come from surface water?
68%
How much of the water in the UK come from groundwater?
32%
What is the drawdown in the cone of depression?
How much the water level falls around a borehole
What are 2 issues with water abstraction from groundwater?
If drawdown is too high, then the water table will fall and there will be a lack of water to feed rivers
Saltwater intrusion into aquifers can be a problem
What are 3 consequences of urbanisation on water cycle?
Reduced infiltration - impermeable
Increased river flows - directed into rivers by storm drains
Reduced interception - trees are removed
What can be done to overcome the issues of urbanisation? 3 ways
Green roofs
SUDS
Increased green spaces
