1. Processes operating within cycle from global to local scale? Flashcards
Why is it a closed system?
➢ Hydrological cycle is a closed system because water is neither created nor destroyed on a large scale.
➢ Water exists as solid, liquid and gas phases that are interchangeable at temperatures found on earth.
What is it driven by?
➢ Solar Energy: Heat energy by Sun
➢ GPE: pulling materials down to earth
Outputs in water cycle [3]
- River Discharge
- Evaporation
- Transpiration
Inputs in water cycle [1]
Precipitation
Transfers in water cycle [7]
- Stem Flow
- Surface Runoff
- Infiltration
- Through flow
- Channel Flow
- Percolation
- Base Flow
Stores in water cycle [6]
- Interception
- Surface Storage
- Vegetation Storage
- Soil Moisture Storage
- Channel Storage
- Ground water
Transpiration?
Process where plants absorb water through roots that give off water vapour through the stomata
Evapotranspiration?
Process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from the plants
Soil moisture Storage?
Amount of water stored in soil. It can be affected by precipitation, temperature, soil characteristics and more
Through flow?
Horizontal flow of water within the soil layer. Normally takes place when the soil is saturated.
Channel flow?
Water flowing through a river
Top 3 storage?
- Ocean
- Cryosphere
- Groundwater
Define Water Budget
➢ Accounting of the rates of water movement
➢ Change in water storage
➢ Parts of the atmosphere, land surface, and subsurface.
Fossil water Storage?
➢ Non renewable
➢ Water stored within the ground over thousands of years
➢ Non-renewable, it takes 1000yrs to make
Types of Rainfall [3]
- Convectional Rainfall
- Frontal Rainfall
- Orographic Rainfall
Convectional Rainfall?
Sun heats the water source to the point that water turns into vapour and rises.
At condensation level, the vapour is usually cooled enough to turn back into the water and fall in the form of rain
Frontal Rainfall?
Two air masses meet, one a warm air mass and one a cold air mass.
Orographic Rainfall?
Rain that is produced from the lifting of moist air over a mountain. Orographic precipitation, rain, snow, or other precipitation produced when moist air is lifted as it moves over a mountain range.
How physical factors affect the relative importance of inputs, flows and outputs?
➢Climate – influences amount of rainfall and vegetation growth.
➢ Soil Composition – influences rate of infiltration and through flow.
➢ Geology – affects percolation and groundwater flow
➢ Relief – steeper gradients of land will encourage faster rates of surface runoff
➢ Vegetation – affects interception, overland flow
➢ Size – larger basins collect more precipitation generally
How human factors affect the relative importance of inputs, flows and outputs?
➢ Cloud seeding – substances dispersed into the air to provide something for condensation to occur on in
➢ Deforestation – Less vegetation means less interception, less infiltration, more overland flow leading to more flooding, cycle speeds up
➢ Afforestation – More vegetation means interception, less overland flow, more evapotranspiration
➢ Dam construction – Dams reduce downstream river flow and discharge, increase surface stores so more evaporation
➢ Change in land use – Infiltration is 5 times faster under forests compared to grasslands. Converting land to farmland means less interception, increased soil compaction and more surface runoff
➢ Ground water abstraction – When water is taken out faster that the water is recharged, groundwater flow decreases and the water table drops Example: In China, groundwater irrigates 40% of farmland whilst 70% of drinking water comes from groundwater
➢ Irrigation – Drop in water tables due to high water usage. Example: Aral Sea in Kazakhstan shrank in 1960s due to farmers using the water to grow cotton
➢ Urbanisation – Impermeable surfaces reduce infiltration, increase surface runoff, river discharge increase.
River Regime?
describe one of two characteristics: The variability in its discharge throughout the course of a year in response to precipitation, temperature, evapotranspiration and drainage basin characteristics
Variations w/Regime: Factors that influence?
▪ Channel capacity of the river
▪ Area and relief of the drainage basin
▪ Volume, pattern and intensity of precipitation
▪ Climate
▪ Geology of the soil (affecting the input of groundwater)
▪ Anthropogenic (human) activities, such as building dams or terracing the land.
Regimes from contrasting river basins? [Case Study]
- Yukon, Alaska (USA)
- Amazon Brazil
- Murray- Darling River
River Regime [CS] : Yukon, Alaska (USA)
High Flow:
Spring and Summer (snowmelt)
Low/ No Flow:
Winter (frozen precipitation)
Seasonal Variability:
Very Large
Human Influences:
Relatively Few- Most of its landscape is wilderness. Some HEP use for mining industries.
River Regime [CS] : Amazon, Brazil
High Flow: Wetter Season (December to May)
Low/ No Flow: Drier Season (June to November)
Seasonal Variability:
Moderate Variability- fed by Andean rivers outside of rainforest region.
Human Influences:
Increasing (although a low percentage of its flow at present); large dams used by Brazil’s major cities for irrigation and HEP.
Purpose of Hydro graphs?
➢Storm hydrographs represent the variation in discharge within a short period of time (days, rather than years)
➢Before a storm begins, the main supply of water to the river is through groundwater or base flow.
➢However, as a storm develops, infiltration and surface runoff will increase which causes a greater throughflow
