Water cycle (drainage basins, hydrographs)
Interception: the retention of water by plants and soils whihc is subsequently stored by vegetation
or evaporated
Infiltration: water soaks into or is absorbed by soil above the water table
Percolation: similar to infiltration, deeper transfer of water in permeable bedrocks below the water
table
Throughflow: the lateral transfer of water downslope throught the soil
Groundwater flow: the slow percolated movemnt of water through permeable or porous rocks
Surface run off: travels on land due to the force of gravity (due to gradient) into a channel
Saturated overland flow: it would infiltrate, but the soil is saturated (likely due to pre -conditions) so
it is forced to travel via overland flow instead
Throughfall: drops off the leaf onto the soil and normally caused by win
Stem flow: when water drips slowly down the stems of plants onto the ground
Explain the factors that affect the rate 0f interception - 4 marks
1. Rate and amount of input - seasonality
2. Presence, density of plant community structure
3. Forms of input - heavy snow, lighter so plants can hold more but heavy rain will go straight
through
4. Species of tree, leaf cover - size of leaf, whether keeps leaves all year round
Interception loss: evapotranspiration of moisture from that has been intercepted by a leaf or
throughfall
Explain the factors that affect the rate of interception loss - 4 marks
1. Need to have a high level of interception in the first place
2. Temperature, high means more lost
3. Surface area of leaf (higher), leaf speices and if it keeps leaves all year round
4. Wind helps increase rate of evapotranspiration by helping to push the motion of water rising
5. Interception capacity (leaves are full of water) more relevant for throughfall
Lag time: the time taken between the peak rainfall and peak discharge, shorter lag time means more
chance of flashy flood
Using figures 1 and 2 suggest reasons for the differences in response to a rainfall event in terms of
lag time - 8 marks
The higher the proportion of overland flow relative to infiltration - the higher the rate of flooding
surface run off is significantly faster than overland
Rising limb - how quick the river is filling up
1. Calculate an exact lag time (subtracting peak rainfall by peak discharge)
2. Geology of soil, whether it is permeable or not
3. The rate and intensity of precipitation
4. Soil coverage (urban areas), like tarmac
5. Interception - high interception will reduce the rate of surface run off and this will shorten
the lag time and cause flashy floods
Interception: the retention of water by plants and soils whihc is subsequently stored by vegetation
or evaporated
Infiltration: water soaks into or is absorbed by soil above the water table
Percolation: similar to infiltration, deeper transfer of water in permeable bedrocks below the water
table
Throughflow: the lateral transfer of water downslope throught the soil
Groundwater flow: the slow percolated movemnt of water through permeable or porous rocks
Surface run off: travels on land due to the force of gravity (due to gradient) into a channel
Saturated overland flow: it would infiltrate, but the soil is saturated (likely due to pre -conditions) so
it is forced to travel via overland flow instead
Throughfall: drops off the leaf onto the soil and normally caused by win
Stem flow: when water drips slowly down the stems of plants onto the ground
Explain the factors that affect the rate 0f interception - 4 marks
1. Rate and amount of input - seasonality
2. Presence, density of plant community structure
3. Forms of input - heavy snow, lighter so plants can hold more but heavy rain will go straight
through
4. Species of tree, leaf cover - size of leaf, whether keeps leaves all year round
Interception loss: evapotranspiration of moisture from that has been intercepted by a leaf or
throughfall
Explain the factors that affect the rate of interception loss - 4 marks
1. Need to have a high level of interception in the first place
2. Temperature, high means more lost
3. Surface area of leaf (higher), leaf speices and if it keeps leaves all year round
4. Wind helps increase rate of evapotranspiration by helping to push the motion of water rising
5. Interception capacity (leaves are full of water) more relevant for throughfall
Lag time: the time taken between the peak rainfall and peak discharge, shorter lag time means more
chance of flashy flood
Using figures 1 and 2 suggest reasons for the differences in response to a rainfall event in terms of
lag time - 8 marks
The higher the proportion of overland flow relative to infiltration - the higher the rate of flooding
surface run off is significantly faster than overland
Rising limb - how quick the river is filling up
1. Calculate an exact lag time (subtracting peak rainfall by peak discharge)
2. Geology of soil, whether it is permeable or not
3. The rate and intensity of precipitation
4. Soil coverage (urban areas), like tarmac
5. Interception - high interception will reduce the rate of surface run off and this will shorten
the lag time and cause flashy floods
