Unit 1A - Our Dynamic Landscape Flashcards
Drainage Basin definition
A Drainage Basin is described as the area of land that is drained by a river and its tributaries.
Why is the drainage basin system often described as an ‘open system’?
The drainage basin is an open system because energy and matter can be transferred across its boundaries.
Water may be evaporated forming clouds in drainage basin A. Wind blows the clouds to drainage basin B. It rains in drainage basin B.
What is hydrology?
Hydrology is the study of water.
What is a flood hydrograph?
A flood hydrograph is a graph which displays discharge (in cumecs) and precipitation (in mm) on the Y-axis and time (usually in days or hours) on the X-axis.
Flood hydrograph
What is a rising limb?
The increase in discharge as rainwater reaches the river.
Flood hydrograph
What is a falling limb?
Some rainwater is still reaching the river but in decreasing amounts.
Flood hydrograph
What is peak discharge?
Highest volume of water in the river at a certain point and at a certain time.
Flood hydrograph
What is peak rainfall?
The highest intensity of rainfall in millimetres.
Flood hydrograph
What is lag time?
Lag time is the difference between the time of the heaviest rainfall and the maximum level and/or discharge of the river.
‘The Water Cycle’ definition
The Water or Hydrological Cycle is a natural system where water is in constant movement above, on or below the surface of the earth, and is changing state from water vapour (gas), to liquid and into ice (solid).
Definition of water table
The level at which saturation occurs in the ground or soil.
Name the processes of the Water Cycle in chronological order and visualise the layout of the drainage basin.
1 - Evaporation 2 - Transpiration 3 - Precipitation 4 - Infiltration 5 - Throughflow 6 - Percolation 7 - Groundwater flow 8 - Surface runoff or Overland flow
Describe each process within the Water Cycle
Evaporation - Water is transformed from seawater into water vapour in the atmosphere.
Transpiration - Water vapour is lost from vegetation into the atmosphere.
Precipitation - Water vapour condenses into drizzle, rain, sleet, snow and hail, and this falls towards the surface of the land.
Infiltration - Water soaks (filters) into the soil.
Throughflow - Water moves downhill through the soil.
Percolation - Water moves from the soil and into the rock.
Groundwater flow - Water moves slowly through the soil and rocks back into the sea.
Surface runoff or Overland flow - Water moves across the surface of the earth, becoming a stream, tributary or river.
Ass 2
Describe the features of a destructive wave
Size - High and close together
Frequent - Up to 15 per minute
Season - Common in winter (storm waves)
Effects - Stronger backwash than swash, erodes beach
Ass 2
Describe the features of a constructive wave
Size - Low and far apart
Less frequent - 6 to 9 per minute
Common in summer
Strong swash, weak backwash - Deposition
Ass 2
What processes cause coastal erosion?
Hydraulic pressure - Force of the waves alone
Abrasion (Corrasion) - Sand papering action of sand and pebbles bashing and smoothing rocks at base of cliff
Solution (corrosion) - Chemical action of seawater dissolving rocks
Attrition - Rocks and pebbles hit each other, breaking up
Ass 2
Describe some processes responsible for coastal transportation
Swash - Wave breaks, carrying water and sediment up the beach
Backwash - Water/sediment returns back down beach due to gravity
Longshore drift - Zigzag movement along beach, etc
Ass 2
How does coastal deposition occur?
The water slows down and has less energy to carry the sediment, it is therefore dropped.
Ass 2
Describe some of the erosional features caused by erosional processes
Wave cut notch - Where waves attack bottom of cliff
Cliff - Forms when unsupported rock falls into the sea
Wave cut platforms - Almost level area as cliff retreats
What is an input in the drainage basin system, and give an example of one.
An input is when water is introduced or put into the system.
Precipitation
What is a store in the drainage basin system, and give examples of some.
A store occurs when water is kept within the system and not moved through it.
Interception (from vegetation)
Soil moisture
Groundwater
Surface storage
What is a transfer in the drainage basin system, and give examples of some.
Transfers are processes or flows within the system, where water is moved from one place to another.
Surface runoff/ overland flow Infiltration Throughflow Percolation Groundwater flow
What is an output in the drainage basin system, and give an example of one.
Outputs occur in the river system when the water is carried through the river and back into the sea.
River discharge
Definition of watershed
The dividing line between one drainage basin and another.