Drainage Basin, Flood Hydrograph, Water Budget Flashcards
what is a drainage basin
A local open system that draws an area with a river
What separates a draingae basin
An imaginary line, usually a ridge of high land
How does basin size affect a drainage basin
larger basin means it takes longer for the water to reach the river
Smaller basin means it takes less time for the water to react the river
How does basin shape affect a drainage basin
A circular basin means all water is equidistant from the river meaning its overall lag time is shorter
A long drainage as in will mean some water will take much longer to meet the river meaning the lag time is longer
How does basin slope and elevation affect a drainage basin
steeply sided basins means gravity assists the water when it is trying to get to the river
Gently sloped valleys tend to produce longer lag times
How does Rock type affect a drainage basin
permeable rock allows water to go through them
impermeable rock does not allow water to go through them causing more surface runoff
How does soil type affect a drainage basin
Sandy soils have high rates of infiltration
Clay soils have very small pore spaces allowing little water flow through
what is water abstraction
it is the extraation of water from rivers and the ground
What is base flow
water that reaches the channel largely through slow through flow and from permeable rock to the water table
What is channel flow
The movement of water within the river channel
This is also called the rivers discharge
What is groundwater flow
The deeper movement of water through underlying permeable rock bellow the water table
what is infiltration
the downward movement of water into the soil surface
what is percolation
The flow of water from the surface into the bedrock
This water usually stays underground for long periods of time
What is surface runoff
The movement of water over the surface of the land
Usually when the ground is saturated or frozen
What is relief rainfall
warm air rises up over mountains from the ocean
it cools and forms clouds causing it to rain
What is conventional rain
occurs in the warmer months
The sun heats the rain causing the rain to rise and cool rapidly forming big clouds
these clouds produce heavy rain and thunder storms
what is frontal rain
When a warm front meets a cold front
The cool air sinks beneath the warm air
The warm air condenses and forms rain
How do humans affect the drainage basin
River Management
Deforestation
agriculture
urbanisation
How does river management affect the drainage basin
construction of water stores slows the river
abstraction of water slows the river
How does deforestation affect the drainage basin
reduces evapotranspiration
increases infiltration and surface runoff
How does agriculture affect the drainage basin
compaction of soil increases surface runoff
ploughing increases infiltration by loosening the soil
How does urbanisation affect the drainage basin
urban surfaces increase surface runoff
drains deliver water to rivers increasing flooding
What is a flood hydrograph
a graph showing the discharge of a river following a particular event
What is a flood hydrograph
a graph showing the discharge of a river following a particular event
What a flood hydrographs useful for
plan for periods of flooding or drought
What a flood hydrographs useful for
plan for periods of flooding or drought
what is the water budget
the balance between the inputs and outputs of a drainage basin
How is the water budget expressed
P=Q+E (+/- change in storage)
What do the letters in the water budget equation stand for
P - precipitation
Q - discharge
E - evapotranspiration
what is water surplus
when there is an excess amount of water available in the system
What is deficiency
When there is a reduction of water available
What is water recharge
After a period of deficiency precipitation will occur and replace the water lost in the soil
What is field capacity
The maximum amount of water that soil can hold before it becomes saturated
