EQ1- what are the processes operating within the hydrological cycle from global to local scale

Question 1

what is a hydrological cycle and what are the powers that drive the hydrological cycle?

Answer 1

a CLOSED SYSTEM
solar energy: in the form of heat
gravitational energy: causes rivers to flow downhill and precipitation to fall to the ground.

Question 2

what are the four main stores of water? which is the biggest?

Answer 2

oceans, glaciers and ice sheets (cryosphere), surface run-off (umbrella term for land-based stores) and the atmosphere.
cryosphere accounting for 69%

Question 3

what are the four main flows?

Answer 3

precipitation, evaporation, transpiration and vapour transport

Question 4

what are fluxes?

Answer 4

the rate of flow between stores

Question 5

what does the residence time of a store mean?

Answer 5

the average time a molecule of water will spend in one of the stores
could range from 10 days to 3,600 years

Question 6

what is a ‘non-renewable’ water store and what are 2 examples?

Answer 6

refers to groundwater bodies that have an insignificant rate of recharge on the human timescale 
fossil water (ancient, deep groundwater from pluvial (wetter) periods)
cryosphere

Question 7

what is a drainage basin?

Answer 7

an OPEN SYSTEM
an area of land drained by a river and its tributaries, sometimes referred to as a river catchment. The boundary is defined by the watershed.

Question 8

what characteristics have significant impacts on the drainage basin?

Answer 8

Form: rain, snow or hail
Amount
Intensity: greater intensity- greater risk of flooding
Seasonality: drainage basin operates at different flow levels at different times of year
Distribution: in large tributaries (Ganges and Nile) tributaries start in different climate zones.

Question 9

what are the 7 different types of flows?

Answer 9

Interception
Infiltration: water soaks/absorbed into soil
percolation: deeper transfers of water into permeable rock
throughflow: lateral transfer of water downslope
groundwater flow: slow transfer of percolated water through porous rock
surface run off: movement of water across the surface of the ground (overland flow)
River or Channel flow: flow of water within a Channel

Question 10

what are the three main outputs of a drainage basin?

Answer 10

evaporation: moisture is lost directly into the atmosphere from water surfaces, soil and rock
transpiration: biological process of water being lost through minute pores from plants
discharge: (also known as channel flow) into another, larger drainage basin, lake or sea

Question 11

what are some physical factors that affect a drainage basin systems?

Answer 11

Climate: influences amount of precipitation and evaporation and vegetation types
Soils: determine amount of infiltration and through flow and type of vegetation
Geology: impacts percolation and groundwater flow
relief: impacts amount of precipitation and run-off
vegetation: impacts interception, transpiration, infiltration and overland flow

Question 12

what are some human impacts on the drainage basin systems?

Answer 12

river management: reservoirs hold water back, abstraction reduces river flows and lowers water tables
deforestation: clearance of trees reduces evapotranspiration but increases infiltration and surface run-off
changing land use (agriculture): arable to pastoral increases overland flow. pastoral to arable increases infiltration through ploughing.
changing land use (urbanisation): increases surface runoff and increases chance of flooding

Question 13

what is evapotranspiration?

Answer 13

the combined effect of evaporation and transpiration from vegetated surfaces

Question 14

how has deforestation disrupted the drainage basin cycle

Answer 14

• lowering of humidities
• less precipitation
• more surface run off and infiltration
• more evaporation, less transpiration
• more soil erosion and silt being fed into the rivers

Question 15

what is a water budget?

Answer 15

annual balance between precipitation, evapotranspiration and runoff.

Question 16

what equation is used to calculate the water budget?

Answer 16

P = E + R ± S
p is precipitation 
e is evapotranspiration 
r is runoff 
s is changes in stores over a period of time (usually a yeaR)

Question 17

what is meant by ‘available soil water’

Answer 17

amount of water that can be stored in the soil and is available for growing crops

Question 18

what is a river regime?

Answer 18

an annual variation in the discharge of flow of a river at a particular point (measured in cumecs)

Question 19

what is a river regime influenced by?

Answer 19

• size of river and where discharge is measured
• amount of precipitation
• temps (evaporation or meltwater)
• geology and soils
• type of vegetation cover
• human activity

Question 20

what does a storm hydrograph show?

Answer 20

shows the discharge changes over a short period of time often no more than a few days

Question 21

what are the main features of a storm hydrograph?

Answer 21

rising limb: rise in discharge as rain starts
peak discharge: reached some time after peak rainfall
lag time: interval between peak rainfall and peak discharge
falling/recession limb: input of rain decreases so discharge does too
base flow: river discharge eventually returns to its normal level

Question 22

what are urbanisations impacts on hydrological processes?

Answer 22

• construction leads to removal of vegetation cover
• soil is replaces by impermeable surfaces
• high density of buildings means rainfall is swiftly fed into drains
• drains reduce distance and time it takes for water to reach streams/river channels
• urban rivers are often channelised
• bridges can act as local dams and reduce discharge of floodwater

Question 23

what are the two different storm hydrography?

Answer 23

Flashy: steep rising limb, high peak discharge and short lag time
Flat: gently inclined limbs, low peak discharge and long lag time.

Question 24

what are interacting factors that lead to the two different hydrographs?

Answer 24

weather/climate: intense storm leads to flashy but gradual rainfall leads to flat
rock type: impermeable leads to flashy and permeable leads to flat
basin size: small basin tends to be more flashy and large tend to be more flat
human activity: urbanisation produces flashy and low pop density produces flat

Question 25

(synoptic themes)

how have players become important in managing the impact of urbanisation on flood risk?

Answer 25

• many towns and cities are naturally prone to flooding due to location
• population needs protecting
• money invested into urban property

Question 26

flood risk management involves actions such as…

Answer 26

• strengthening of embankments of streams and rivers
• putting in place flood emergency procedures
• steering urban development away from high-risk areas such as floodplains