Water Flashcards
What is the difference between flows and fluxes?
Flows are movements of water from one system to another, fluxes are a measurement of the rate of flows between stores
Which words are used to describe water moving in/out of a store?
Inputs and outputs
Which is the largest hydrological store and what % of total water does it take up?
Oceans, 96.9%
What is the hydrological cycle driven by?
Solar (e.g. evaporation/precipitation) and gravitational potential energy
What is the order of fluxes from largest to smallest?
Evaporation –> precipitation –> groundwater runoff –> evapotranspiration
What type of system is the global hydrological system and what does this mean?
Closed system, transfer of energy but not matter between system and its surroundings
What type of system is the local (drainage basin) hydrological system and what does it mean?
Open system, volume of water in drainage basin isn’t fixed over time
What are the 7 flows of water within a drainage basin?
- Interception
- Infiltration (soil)
- Throughflow
- Percolation (rocks)
- Groundwater flow
- Overland flow
- Saturated overland flow
What are the 3 types of interception (precipitation stopped by vegetation)?
- Interception loss
- Throughfall
- Stem flow
What is the 1 input and 3 outputs of water within a drainage basin?
Input: Precipitation
Outputs: Channel flow, evaporation, transpiration
What are the 3 types of precipitation and where is each type found?
- Convectional - tropics e.g. Amazon
- Orographic - mountains e.g. Himalayas
- Frontal/cyclonic - mid latitudes e.g. UK
Describe the process of convectional rainfall
- Solar energy from the Sun warms the Earth’s surface
- Earth’s surface warms overlaying air
- Air expands, becomes less dense, and rises
- Rising air cools, reducing ability to hold water vapour
- Water vapour condenses as air reaches saturation and dew point
- Clouds form as condensation forms around condensation nuclei and process continues until rain falls
Describe the process of orographic rainfall
- Air forced to rise up stoss side of mountain
- Air cools, reducing ability to hold water vapour
- Air reaches saturation and dew point
- Condensation forms around condensation nuclei
- Clouds form on stoss side where rain falls
- Rain shadow formed on leeward side
Describe the process of frontal/cyclonic rainfall
- As warm and cold air masses meet, warm air forced to rise over cold air mass because less dense
- Air cools and reduces ability to hold water vapour
- Air reaches saturation and dew point
- Condensation forms around condensation nuclei
- Process continues and rain falls
What are the 3 river case studies for river regimes and where are they located?
- River Yukon - North America
- Amazon River - South America
- River Indus - India
What does the River Yukon’s river regime look like?
Stays constant until river discharge increases then decreases
Why does the River Yukon’s river regime stay constant until river discharge increases then decreases?
- Precipitation falls as snow and stored in cryosphere
- April: Temp. increases so water moves from cryosphere to hydrosphere and travels to river via OLF and precipitation falls as rain so steep increase in river discharge
- May: Temp. increases so ice melt enables infiltration, percolation, groundwater flow which feeds base flow as temps. drop again
What does the Amazon River’s river regime look like?
Relatively stable but increases and then decreases
Why does the Amazon River’s river regime stay relatively stable but increases and then decreases?
- Spring: Sun directly overhead so creates convectional rainfall due to ITCZ
- June: Peak discharge reached but takes 4 months for tributaries to contribute due to large basin
- Autumn: Earth tilts away from Sun in S. hemisphere so decreased convectional rainfall as ITCZ has shifted north
What does the River Indus’ river regime look like?
Slight increase, levels off, increases again to reach peak discharge, then decreases
Why does the River Indus’ river regime have 2 peaks and then decreases?
- April: Temp. increases so river fed by snow melt from Himalayas so increased river discharge
- May: Hits initial peak discharge due to drainage basin’s topography
- June: Monsoon season associated with Northwest shift of ITCZ so increased convectional rainfall and steep increase in river discharge due to saturated soils
- Dry season starts so discharge rapidly drops with increased evaporation and water locked in cryosphere in Himalayas again
What 3 ways can humans impact flows and fluxes in a drainage basin?
- Dam construction
- Urbanisation
- Cloud seeding
What is the case study for dam construction impacting flows and fluxes in a drainage basin?
Dams in the Niger Delta
By what % have upstream dams in the Niger Delta reduced flows into the delta?
15%
How does dam construction impact flows and fluxes in a drainage basin?
Reduces evaporation and precipitation when wetlands are drained and woodlands are deforested so less inputs
What is the case study for urbanisation impacting flows and fluxes in a drainage basin?
2015 flood of York (River Ouse)
How does urbanisation impact flows and fluxes in a drainage basin?
Creates more impermeable surfaces e.g. concrete which reduce infiltration, throughflow, percolation, groundwater flow and increase OLF which decreases lag time and increases peak discharge
What is the case study for cloud seeding impacting flows and fluxes in a drainage basin?
Used in 2015 in Texas to reduce impact of drought
How does cloud seeding impact flows and fluxes in a drainage basin?
Substances released into air which act as condensation nuclei and change the amount/type of precipitation
What are the 2 types of storm hydrograph?
Flashy and delayed
What do you always need to link to when talking about storm hydrographs?
Lag time and peak discharge
What 3 physical factors create a flashy storm hydrograph?
- Climate (intense rainfall)
- Relief (steep topography)
- Geology (non-porous rocks)
How does intense rainfall lead to a flashy storm hydrograph?
Soil moisture holding capacity exceeded so less infiltration, throughflow, percolation, groundwater flow so saturated OLF so decreased lag time and more water arriving at river at same time so increased peak discharge so flashy storm hydrograph
How does a steep topography lead to a flashy storm hydrograph?
Increased gravitational potential energy so water travels faster via OLF so decreased lag time and increased peak discharge so flashy storm hydrograph
How do non-porous rocks e.g. igneous rocks lead to a flashy storm hydrograph?
Less percolation and groundwater flow so increased OLF so decreased lag time and increased peak discharge so flashy storm hydrograph
How can a PAD about storm hydrographs be linked to flood risk?
Higher/lower risk of flooding as peak discharge is more/less likely to exceed bankfull discharge
How does deforestation influence storm hydrographs?
Less vegetation so less interception and transpiration so soil saturated more quickly so less infiltration, throughflow, percolation, groundwater flow so water travels more quickly via saturated OLF so decreased lag time and more water arriving at same time so increased peak discharge (long term nutrients washed away so less vegetation)
What % of water is returned to the atmosphere by the evapotranspiration of vegetation?
25%
What is the linked evaluation for deforestation influencing storm hydrographs?
Increased environmental awareness so increased consumer demand surrounding protection of habitats so companies investing into afforestation programmes
Which company decided to plant 3 trees for every 1 tree they cut down?
Velvet
What is the linked evaluation for urbanisation influencing storm hydrographs?
Better environmental planning so more infiltration, throughflow, percolation, groundwater flow so longer lag time and decreased peak discharge as water reaching river at different times
Which car park has a grid over pebbles instead of concrete?
Jodrell Bank car park
How do bridges influence storm hydrographs/flood risk?
Debris blocks channel so channel flow volume increases upstream so peak discharge more likely to exceed bankfull discharge
What is the case study for bridges influencing storm hydrographs/flood risk?
2004 Boscastle floods
What is meant by a positive and negative water balance with examples?
Positive: Inputs > outputs e.g. UK
Negative: Outputs > inputs e.g. Sahel
(Inputs = precipitation, outputs = evapotranspiration, runoff)
What does soil moisture budget show?
How much water is held within soil store in a drainage basin
What are the 4 stages of a soil moisture budget?
- Soil moisture surplus (inputs > outputs)
- Soil moisture utilisation (outputs > inputs)
- Soil moisture deficit (outputs > inputs)
- Soil moisture recharge (inputs > outputs)
Explain how El Nino causes drought in Australia
- Westward trade winds reverse so cold water off coast of Peru replaced by warm water and warm water off coast of Australia replaced by cold water
- Rising ocean temps. creates convectional rainfall on coast of Peru, creating wetter conditions
- Dry air returns to Australia so less precipitation which leads to meteorological drought
What is an example of a drought caused by El Nino?
Big Dry 2006 in Australia
Which current provides cold, nutrient-rich water to Peru and by what % are fish stocks in Peru reduced by during El Nino?
Humbolt current, 45% reduction as current can’t reach the surface