Geography - Hydrology & Fluvial Geomorphology Flashcards

Terms Definitions
Closed system
There is input, transfer, and output of energy but not of matter (or mass)
Open system
Most environmental systems are open and there are inputs and outputs of both energy and matter
Why is the hydrological cycle a closed system?
Water does not enter or exit the cycle. The water used is always the same, therefore there is no transfer of mass/matter
Drainage basin - inputs
Precipitation
Drainage basin - storage
Interception
Surface storage
Vegetatin Storage
Soil water storage
Ground water storage
Channel storage
Drainage basin - transfers
Throughfall
Stemflow
Infiltration
Surface runoff (Overland flow)
Throughflow
Percolation
Ground-water flow (baseflow)
Channel flow
Drainage basin - outputs
Transpiration
Evaporation
River runoff
Explain what happens in the hydrological cycle
1. Sun heats ocean
2. Ocean water evaporates and rises into the air
3. Water vapour cools and condenses to become water droplets, which form clouds
4. If enough water condenses, the drops become heavy enough to fall to the ground
5. Some rain collect on ground wells, the rest flows through rivers and back to the ocean
What is a drainage basin?
An area of land drained by a river and its tributaries
What is a tributary?
A smaller river that runs or flows into the main body (trunk) of the river system
How do you recognise the drianage baisns boundaries?
The boundary is marked by a ridge of high land beyond where any precipitation will drain into neighbouring basins
What is the drainage basins, boundary called?
Watershed
What are the 7 factors that affect infiltration?
1. Intensity of precipitation
2. Duration of rainfall
3. Soil type
4. Amount of vegetation cover
5. Depth of water table
6. Slope of land
7. Human activity
Interception
The process by which precipitation is trapped on the surface of vegetation
Surface storage
Water sitting upon the Earths surface, not being transferred
Soil moisture/groundwater
The store of water held beneath the water table
Infiltration
The process by which water on the Earths surface moves into the soil store
Percolation
Water in the soil store flows vertically through soil and rocks. Down into deep groundwater stores
Surface runoff (overland flow)
Water flows horizontally across the surface of the land
Through-flow
The movement of water horizontally throught the soil and subsoil, from soil storage to channel storage
Groundwater flow
The store of water held beneath the water table
What is precipitation affected by?
Amount of rainfall.
The shorter the duration, the higher the intensity if the rainfall
What is EVT affected by?
Temperature
Wind speed
Humidity
Hours of sunshine
Transpiration depends on the time of year, type and amount of vegetation, availabilty of moisture and the length of the growing season.
Potential EVT differs from actual EVT
What is interception affected by?
A woodland area would allow for greater interception, where as a grassed/farmed area would allow less interception
What is surface runoff affected by?
The amount of rainfall and how saturated the soil is
What is infiltration affected by?
The infiltration capacity (or maximum rate at which infiltration occurs) depends on:
1. Antecedant precipitation (moisture already in the soil) and
2. Porosity
What is percolation affected by ?
The more compact the soil/bedrock, the lower the percolation
Percolation affects groundwater storage
What is groundwater flow used for?
Rivers draw on this in dry periods
What is channel flow affected by?
This is affected if water is sotred in dams etc, or used for other purposes such as irrigation, etc
Hydrology
The study of water in a natural environement
Hydrological cycle
This refers to the constant recycling of water between the oceans, atmosphere and land
Inputs
Energy or matter that enters into a system
Outputs
Energy or matter that leaves a system
Stores
Natural reservoirs of water in the environment, such as rivers, lakes, soil vegetation, the atmosphere and the water table
Flows
Paths that water follows in the land based part of the hydrological cycle.
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