EQ1- What Are Processes Operating In The Hydrological Cycle From Global To Local Scale Flashcards
Define a closed system
When there is a transfer of energy between the system and its surrounding. There are no external inputs/outputs, any inputs come from within the system
The earths water is a closed system
Define flows (fluxes)
Measurements of the rate of flow between stores
Define Processes
Physical mechanisms such as evaporation that drive the flows pf water between the stores
Define Stores
Reservoirs where water is held e.g. oceans
Define Blue water
Water that is stored in rivers, streams, lakes and groundwater in liquid forms
Visible
Define green water
Water stored in the soil and vegetation
Invisible
What are the 4 different stores
Oceans
Cryosphere (ice and snow)
Terrestrial (where living things are)
Atmosphere
Describe the water store and residence time of oceans
96.9 % of worlds water store
3600 years of residence time
Describe the water store and residence time for the cryosphere
1.9% of water store
15,000 year residence time
(Precipitation falls as snow)
Describe the water store and residence time of terrestrial
1.1101 % of water store (made up of ground, surface, biosphere and soil)
1 week to 10,000 year residence time
Describe the water store and residence time of the atmosphere
0.01% of water store
10 days residence time
Describe the water cycle
flow
Precipitation
(Can lead to) Surface run off/Infiltration/percolation/groundwater flow
(Leads to) Evapotranspiration [through living things]/Evaporation/Cryospheric process [evaporation or sublimation]
(Leads to) Vapour transport (in clouds)
Define the cryosphere
Areas of the earth where water is frozen into snow/ice
Define residence time
The amount of time a water molecule will spend in a reservoir or store
What is fossil water
Deep groundwater from former pluvial (wetter) periods
Water is inaccessible
Define Precipitation
What is it
All the ways moisture comes out the atmosphere
Input
Define interception
What is it
Is when some precipitation lands on vegetation or other structures, before it reaches the soil. It is a temporary store because the water evaporates quickly
Store
Define surface storage
What is it
Includes water stored in puddles, ponds and lakes
Store
Define groundwater storage
What is it
Water stored in the ground, either in the soil or in rocks
Store
Define the water table
The top surface of the zone of saturation - the zone of soil or rock where all the pores in it are filled with water.
Define Aquifers
Porous rock that holds water
Define channel storage
What is it
Water held in a river or stream channel
Store
Define surface run off
What is it
Water flowing over land. It can be when it cannot infiltrate through the ground
Transfers
Define Throughfall
What is it
Water dripping from one leaf to another.
Also is water moving slowly downhill through soil.
Transfer
Define stemflow
What is it
Water running down a plant stem or tree
Transfers
Define Infiltration
What is it
Water soaking into the soil. Influenced by soil type, structure and how much water has already infiltrated the soil.
Transfers
Define Percolation
What is it
Water seeping down through soil into the water table
Transfer
Define Groundwater flow
Water flowing slowly below the water table and through the permeable rock
Define Channel flow
What is it
The water flowing in the river or stream. Also called the rivers discharge
Transfer
Define evaporation
What is it
Water turning into water vapour
Output
Define transpiration
Evaporation from plant leaves, it takes water through the roots to the leaves.
Output
How does solar energy and GPE drive the global hydrological cycle
Solar energy causes evaporation and transpiration
GPE keeps the water moving through the system
What is the global water budget
The annual balance of water fluxes and the size of the water stores
What does non renewable water mean
Means some water stores are non replenishable
Climate change is causing water in the cryosphere to melt and be lost
Why can we only access a small amount of the earths water
The majority of our water is salinated, meaning it cannot be used.
Water stored in aquifers, soil moisture and glaciers are unavailable with the technology we currently have
What are the main impacts on the drainage basin : inputs
Amount of precipitation (impacts discharge)
Type of precipitation (rain,snow or hail)
Seasonality(seasonal patterns)
Intensity of precipitation
Variability (secular long term, periodic seasonal or stochastic random
Distribution of precipitation within a basin
What are the main impacts on the drainage basin : outputs
Evapotranspiration
Channel flow
How does evapotranspiration impact the drainage basin
4 factors
Temperature - increase of temperature (solar energy) increases evaporation rate
Wind - reduces the relative humidity and prevents saturation of air so evaporation increases
Vegetation cover - transpiration will increase with increased vegetation cover
Soil moisture content- determines the amount of water available for transpiration
How does channel flow effect the drainage basin
Dependent on the amount of precipitation falling directly into the channel and other transfers. Intense rainfall and increases in transfers increases the channel flow
What are the three inputs into the drainage basin
Convection rainfall
Frontal (cyclonic) rainfall
Orographic (relief) rainfall
Describe how convection rainfall works
Happens in warmer areas where it heats the air above it.
The heated air rises and condensates and cool air rushes in to replace the warmer air.
This forms cumulonimbus clouds
Describe frontal (cyclonic) rainfall
There are warm fronts and cold fronts
Warm air is forced to rise when undercut by colder air
It expands, cools and condensates forming cumulonimbus clouds
Describe how orographic (relief) rainfall works
Happens in mountainous areas where warm air is forced to rise over it.
Air cools and condensates, rain occurs and is more intense of high land
In flatter land a rain shadow forms where there is no rain
What are the factors which effect flows in the drainage basin: stores and transfers
Infiltration
Interception
Surface run off
Percolation and groundwater flow
How does Infiltration rates effect the drainage basin
Precipitation directly infiltrates into the ground
Dry soil or frozen soil means infiltration cannot happen
Previous wet conditions means soil may be over saturated so infiltration does not occur
How does interception effect the drainage basin
More solar energy means water is quickly evaporated
Different types of precipitation like snow may be too heavy for some trees, only coniferous tress could deal with intense snowfall
Intense rainfall may mean some crops are not strong enough to intercept precipitation.
How does surface run off effect flows in the drainage basin
Intense torrential storms cause infiltration rates to exceed so more surface run off
High surface run off rates can cause high channel storage and high soil erosion and sediment erosion
How does percolation and groundwater flow effect flows in the drainage basin
Different types of rock can effect percolation - impermeable rock means no percolation, permeable rock has more pore spaces so percolation can happen
A steeper gradient allows groundwater flow to increase
What are the human disruptions that effect the inputs in the drainage basin
Explain it and give an example
Cloud seeding- Is when water is heated to force it to rise and condensate, it changes the amount/type of precipitation
An example is in China where they used cloud seeding to create rain to clear the air pollution
What are the human disruptions that effect the output in the drainage basin
Give an example of it and explain it
Dam construction - Increase the surface water stores and evaporation and reduce downstream river discharge
The Lake Vassar in Egypt had huge evaporation losses due to the Aswan Dam
Name the human disruptions which effect the stores/transfers of the drainage basin
Deforestation Afforestation Urbanisation Groundwater Abstraction Arable and pastoral farming
Explain Arable and pastoral farming and how it effects the drainage basin
Causes an increase in surface run off as there is no interception and reduces infiltration as soil quality is poor
Explain : i. Deforestation ii. Urbanisation iii. Afforestation As how these human disruptions effect the drainage basin
Deforestation - Causes an increase in surface run off and a decrease in interception, water infiltrates quicker
Afforestation - causes a decrease in surface run off as there is more interception, increases transpiration
Urbanisation- Increases surface run off and storage as water cannot infiltrate through impermeable surfaces, seen in London
Explain Groundwater Abstraction and how it can effect the drainage basin
Give an example
Caused by groundwater being extracted from aquifers faster than its replaced, causing reduced groundwater flow
Seen in China for industrial processes
Define water budget
Reflects the natural annual balance between inputs and outputs in a given river area
What is the formula for precipitation
Precipitation (p) =Channel discharge (Q) + Evapotranspiration
+- channel in store
What is field capacity
The normal amount of water that can be held in the soil
What is potential evapotranspiration
Is the amount of water that could be lost by evapotranspiration if there was sufficient moisture available
What is actual evapotranspiration
The amount of water that is lost through transpiration and evaporation to the atmosphere
What is soil moisture surplus
What is the relationship between precipitation and evapotranspiration
Occurs when the soil moisture store is full and there is excess water available for plants, runoff and recharge
Evapotranspiration is greater than precipitation
What is soil moisture utilisation
What is the relationship between precipitation and evapotranspiration
Occurs when moisture from the soil stores is being used by vegetation/humans
Precipitation is less than Evapotranspiration
What is soil moisture recharge
What is the relationship between precipitation and evapotranspiration
Occurs when moisture from precipitation infiltrates and percolates in the stores to repay the soil moisture utilisation/deficit
Precipitation is greater than evapotranspiration
What is soil moisture deficit
What is the relationship between precipitation and evapotranspiration
There is not enough water left in the soil to match potential.
Evapotranspiration is greater than precipitation for a prolonged period of time
What do water budget graphs provide
A direct comparison of natural water supply and demand and the impact it has on soil water availability
How could less rain in the winter effect the water budget graph
Mean soil has not reached full full field capacity
Less soil moisture surplus
Soil moisture deficit may be earlier than normal
How could cooler weather in the summer effect the water budget graph
Less actual evapotranspiration
Less soil utilisation
Take longer to reach soil moisture deficit
How would the water budget graph for the UK look
General constant level of precipitation with a slight dip in the summer months
Big build up of evapotranspiration and reaches maximum in July
There is a soil moisture surplus between October - March
Soil moisture surplus May - August
How would the water budget graph look for Alaska (polar climate)
High build up of precipitation until July and August
High evapotranspiration in July
Soil moisture surplus from september - march
Soil moisture deficit from April- August
How would the water budget look for Egypt (warm climate)
High soil moisture deficit all year round
Low precipitation levels
High evapotranspiration levels
What challenges do humans face in the UK’s water budget
Soil moisture deficit in Summer months
What challenges do humans face with Alaska’s water budget
No evapotranspiration from october to april meaning it can be hard for vegetation to survive
What challenges do humans face for Cairo’s water budget
High soil moisture deficit and low soil moisture recharge
Define River Regimes
Indicate the annual variation of the discharge of a river at a particular point and is measured in cumecs
Explain the factors which effect the nature of a rivers regime (7)
The size of a river
Amount, pattern and intensity of precipitation
Temperature
The geology and soils (porosity and permeability)
Amount of vegetation cover
Human activities
Climate
What is a simple river regime
Where a river experiences a period of seasonally high discharge followed by low discharge.
An example are rivers within temperate climates, which rise in mountainous regions where summer snowmelt occurs.
What is a complex river regime
These are where large rivers cross several different relief and climate zones, and therefore experience the effects of different seasonal climatic events.
E,g, The Mississippi River
What is a storm hydrograph
What do there shape depend on
A graph showing variation in discharge of water at a given point over a short period of time , normally an individual storm
What do storm hydrographs shape depend on
Storm hydrographs shape depends on physical factors of the drainage basin (size, shape, drainage density, rock type, soil, relief and vegetation) as well as human factors (land use and urbanisation)
How does land use effect the hydrological cycle and hydrograph
Decrease in evapotranspiration because there is less vegetation in urban areas. This decreases the lag time.
Increase in surface run off due to no infiltration and percolation in urban areas with impermeable concrete. This increases peak discharge and storm flow.
Decrease in infiltration and percolation which causes a decrease in lag time and high peak discharge
What is a sustainable drainage system
Give examples
Prevents surface water flooding as flow rates are decreased and water storage capacity is increased
Examples:
Permeable pavements (gaps to allow infiltration)
Wetlands (retention areas like wetland bogs)
Soak away (disperses surface water into the ground)
Detention basins (delay storm run off)
What is base flow
When a river flows normally
What is rising limb
Increase in discharge in response to surface run off and through flow , until peak discharge is reached
What is peak discharge
The maximum discharge by a river in response to a rainfall event
What is bankfull discharge
When a rivers water level reaches full capacity
What is falling limb
The decline in discharge that occurs after peak discharge
What is lag time
The difference in time between peak rainfall and peak discharge
What is the approach segment
Shows the discharge of a river before the storm
