Precipitation definition
Rain, snow, hail and sleet
Infiltration definition
When water enters the ground
Interception definition
When water is caught by trees and plants
Stem flow definition
Water lands on plants and runs down their stems
Overland flow definition
Anywhere water flows over the land surface
Through flow definition
When water flows through the ground
Transpiration definition
When water vapour comes out of leaves
Evapotranspiration definition
Water rises as vapour from the ground or released from leaves
Ground water definition
Water deep in the ground
Soil water definition
Water held between soil particles
Ground water flow definition
The slow movement of water through the ground
Percolation definition
Movement of water down through the ground
Surface storage definition
Lakes, ponds and puddles
Ground water storage definition
Water stored underground in bed rock
What is the drainage basin?
The area of land surrounding a river, from which the river remains cornices water and subsequently drains this water
Movement of water through the drainage basin (quickest to slowest)
- fastest movement of water occurs along the surface (especially urban areas)
- relatively free movement in woodland as there are many channels created by roots
- water moves through soil at a slower rate
- below the soil the rate of transfer slows considerably
What is the water balance?
The difference between the inputs and outputs (and the subsequent change in storage) in the drainage basin
How does a positive water balance occur?
If precipitation exceeds run off and evapotranspiration there will be a positive water balance
How does a negative water balance occur?
If run off and evapotranspiration exceeds precipitation, there will be a negative water balance
Water balance equation
P=Q+E+/-change in storage
P= precipitation Q= total runoff E= evapotranspiration
What is the soil moisture budget?
The change in the amount of water stored in the soil throughout the year
Potential evapotranspiration definition
The amount of evapotranspiration that could occur if there was sufficient water available in the system
What is the river regime
The variability in the rivers discharge throughout the course of the year in response to precipitation, temperature, evapotranspiration and drainage basin characteristics
What is climatic variation?
-changes in seasonal temperature mean evapotranspiration losses are heavily concentrated in the summer
What is a hydrograph?
A graph of river discharge against time
Role of climatic factor in the variation of global water stores
- cryospheric (ice) stores decrease as a result of global temperature increase
- ice sheets on land melting cause an increase in water stores
- an increase in temp. increases the rate of evapotranspiration
- decrease in temp. reduces oceanic water store as water freezes on the land
- this increases cryospheric stores
Storm hydrograph- peak rainfall
The highest level of rainfall that the rainstorm reached
Storm hydrograph- peak discharge
The highest level of discharge in the river during the rainstorm
Storm hydrograph- lag time
The time taken from the peak rainfall to the peak discharge
Storm hydrograph- rising limb
How quickly a river responds to a storm
Storm hydrograph- falling limb
Discharge decreasing after a storm event
Storm hydrograph- base flow
The lowest amount of discharge in the river basin
Storm hydrograph- storm runoff
The amount of water that runs off during a storm
Natural causes of flooding in Pickering Beck
- steel sided valley that water runs off into the beck
- discharge averages 29.9 cumecs- higher than average
- geology of gritstone and limestone and soft sand- ground becomes quickly saturated and water has to travel as surface run off
Human causes of flooding in Pickering Beck
- overgrazing
- urbanisation has led to increase in impermeable surfaces
- A170 runs directly through Pickering- one of the main areas to flood
Land management strategies in Pickering Beck
- large low level embankment is being built to create additional flood storage capacity
- floodplain woodland can form a barrier to flood flows (19 ha planted in Pickering Beck so far)
- small scale planting by local residents can help protect areas at risk of high percentage of surface runoff