Water Cycle 2

Question 1

Give 4 possible ways human can affect the water cycle within a drainage basin (local scale)

Answer 1

Throughout the world there have been major changes to the water cycle from climate change and land use change

Deforestation means there is less interception so overland flow increases. Also decreases evapotranspiration so maybe less precipitation from conventional rainfall

Land use change may increase flood risk (urbanisation, deforestation)

Humans modifying the flows of rivers by abstraction of water (dams). When water is released back it may be of different tempatue/quality

Question 2

Give 3 types of system

Answer 2

Open

Closed

Isolated

Question 3

What is an open system

Answer 3

Moist environment systems are open and there are inputs and outputs of both energy + matter

Question 4

What is a closed system

Answer 4

Inputs and output of energy but not matter (planet earth)

Question 5

What is an isolated system

Answer 5

No input or output of energy or matter (universe)

Some claim this idea is not applicable to geography

Question 6

What is dynamic equilibrium

Answer 6

When opposing inputs and outputs in the system are balanced

Question 7

Give an example of a cause on the water cycle for disrupting the dynamic equilibrium of a system

Answer 7

Prolonged heavy rainfall causes an increase in the discharge and velocity of a river, increasing rate of erosion

Question 8

How do Chroley and Hagget describe systems

Answer 8

A simplified structuring fo reality which presents significant features/relationships in a. generalised form, allowing the fundamental aspects of reality to appear

Question 9

An open system tends to…….itself by modifying the interrelationships between different elements fo the system so….and output flows………each other out

Answer 9

Adjust
Inputs
Balance

Question 10

What is feedback

Answer 10

Occurs when one element of a system changes because of an outside influence, upsetting the dynamic equilibrium

Question 11

What is negative feedback

Answer 11

When a system acts by lessening the effects of the original change and ultimately reverses it

Question 12

What is positive feedback

Answer 12

When a change causes a further/snowball effe t, continuing or accelerating the original change

Question 13

What is the dew point temperature

Answer 13

The temperature bellow which droplets begin to condense and dew forms (air saturated)

Question 14

How does precipitation vary worldwide

Answer 14

Influenced by general circulation of the atmosphere, proximity to large bodies of water and topography

Question 15

Give the 4 global stores of water, their percentage of total water and residence time

Answer 15

Hydrosphere (97%) 3,600 years

Lithosphere (1.7%) 10,000 years

Cryosphere (1.7%) 15,000 years

Atmosphere (0.001%) 10 days

Question 16

Why are residence times longer in larger stores

Answer 16

Big stores - vast majority fo water molecules are very far from he boundary and thus takes a long time to escape

Question 17

Are the cryosphere and hydrosphere in a state of equilibrium

Answer 17

No

Crysophere - more out than in

Hydrosphere - More in than out (Global warming) (opposite in ice age - temperature dependent)

Lithosphere and atmosphere tend not to change a great deal

Question 18

What does the atmosphere have such short residence times

Answer 18

Water only stays in atmosphere if not very dense (air can only hold so mcc water for a limited amount of time)

Question 19

Do the water stores experience a significant change in volume

Answer 19

Whilst the overall volume of water contained in stores does not change significantly on the global scale, transfers and flows will affect the amount of water over time that remains in a store

An example = how levels of evaporation increase in summer which leads to higher atmospheric storage and a slight drop in ocean storage.

However, these are not significant changes in volume and the ocean will always remain the primary store in water cycle

Question 20

Give 4 transfers that slightly change the size of the stores

Answer 20

Evaporation

Condensation

Cloud formation

Precipitation

Question 21

How does evaporation affect the amount of water held in stores

Answer 21

The level of evaporation on global scale ocean and sea levels is minima but within a drainage basin, evaporation can have a large regional impact

Lakes/rivers in areas of high summer temperatures will experience high levels of evaporation and hydrological storage will reduce significantly in that area

Question 22

How do clouds form

Answer 22

When water molecules aggregate - temperatures drop at altitude to allow condensation

Question 23

How does precipitation occur

Answer 23

When the water molecules within a cloud combine and become to big (coalescence)

If the droplets fall velocity is greater than the clouds updraft velocity, precipitation will occur

Question 24

Give 4 reasons for differing rainfall patterns globally

Answer 24

Desert areas have limited rainfall as they receive sinking dry air from pressure systems

Large continental interiors tend to be dry because of distance from moisture sources and many clouds loose moisture before they reach the centre of large continents

Polar areas are dry because cold air cannot hold as much moisture as warm air, less precipitation

Areas near equator receive high rainfall amounts because constant solar heating produces intense heating, large-scale evaporation and moist rising air that cools with altitude and forms convectional rainfall

Question 25

Why do mountain ranges near water sources reviewed high levels of precipitation

Answer 25

Precipitation occurs when clouds rise to go over mountains and the air cools which encourages the water molecules to join and then precipitation occurs (relief rainfall)

Question 26

Why are hydrographs important

Answer 26

Can be used in predicting the flood risk and in making the necessary changes

Question 27

Put factors influencing hydrographs into 3 groups

Answer 27

Climate Natural catchment Land use

Question 28

How do 3 different types of precipitation influence the shape of a hydrograph

Answer 28

Prolonged rainfall - flashy hydrographs most frequently occurs following a long period of heavy rainfall when the ground has become saturated Intense storms - when heavy rain occurs, the rainfall intensity may be greater than the infiltration capacity of the soil, causing surface run-off and flash floods Snowfall - heavy snowfall means water is held in storage and river levels drop initially. When temperatures warm, meltwater soon reaches river though ground may be frozen so infiltration impeded

Question 29

How does temperature influence infiltration

Answer 29

Extremes can restrict infiltration and increase surface runoff ``` Very cold (frozen) in winter Hot, dry in summer ```

Question 30

Gve some interrelationships between factors influencing the shape of the hydrograph

Answer 30

When considering natural catchment characteristics, geology is an important control Fcsators that impact on the hydrograph like rock permeability, groundwater storage capacity and soil type all stem from the underlying geology Combination of a multitude of factors that will determine the shape of the hydrograph

Question 31

How big is the Mississippi drainage basin

Answer 31

4th largest in the world (1.2 million square miles)

Question 32

Give 3 physical factors that influence the run-off and consequently, flow of the Mississippi-river

Answer 32

Precipitation/snowmelt Corresponding variability between precipitation and evapotranspiration Weather events - storms/droughts

Question 33

How does precipitation/snowmelt affect the flow of the Mississippi River

Answer 33

Maintained by precipitation/snowmelt (paramount factor), however, not all runs off into river channels Some infiltrates into spil and is eventually transpired or evaporated directly Over the basin, evapotranspiration losses account for over 75% the annual precipitation However, these losses vary regionally. Arid western part, very little water is left to run off and most of the river's run off is indebted to wetter eastern part of basin

Question 34

How does variability in precipitation and evapotranspiration affect the flow of the Mississippi River

Answer 34

Flow varies over time Seasonally, there is an increase in precipitation in winter months compared to drier summer months. However, this simple seasonal pattern is far too simplistic and there is a variability in precipitation levels within the seasons North west region receives lower rainfall than the S.E corner, particularly Nov-Feb. The uneven nature of rainfall distribution as well as the amount of it significantly alters runoff levels throughout the year

Question 35

How do weather events (storms) affect the flow of the Mississippi River

Answer 35

Impact upon the amount of runoff within the basin and the flow shape of the hydrograph High levels of precipitation can lead to saturated soil as soil water storage limits are reached This can lead to increased surface runoff which increases discharge within river channel E.g 2014 summer - record rainfall fell in Minnesota, Iowa and Illinois leading to a flood in the upper Mississippi basin

Question 36

How do weather events (droughts) affect the flow of the Mississippi River

Answer 36

Limited precipitation reduce river discharge initially However, over a longer time period, drought conditions can harden the soil, making it impermeable and increasing runoff during a period of subsequent rainfall

Question 37

What is the main human activity that significantly influences runoff in the Mississippi River

Answer 37

Agriculture Constitutes a key economic activity in arid western part which provides 92% USA's total agricultural exports

Question 38

How does agriculture influence the Mississippi River

Answer 38

Large volumes of runoff are collected in man-made reservoirs, which is then extracted and irrigates crops Changes the water cycle as water is diverted from surface runoff/infiltration and through flow - greatly impacting the amount water reaching the river Chanel Storage and mass use off irrigation results in higher levels of evapotranspiration from crops, so water returned to atmosphere instead of hydrosphere

Question 39

Give 3 human impacts on the Mississippi River

Answer 39

Agriculture Reservoirs Climate change

Question 40

How do reservoirs influence the Mississippi River

Answer 40

43 dams along course of Mississippi which hold back water 6% of total runoff is transferred to atmosphere by the higher levels of evaporation during summer from surface reservoirs Increasing population and demands for domestic and uindustrial use has meant it will only continue

Question 41

How does climate change influence the Mississippi River

Answer 41

Predictions estimate a reduction of 5 inches of rainfall a year in the lower basin due to changing precipitation patterns Less rainfall = decreasing runoff and channel flow

Question 42

What is meant by potential evapotranspiration

Answer 42

The highest amount of evapotranspiration possible (theoretical) with unlimited water

Question 43

Define the water balance

Answer 43

Balance between the inputs and outputs of a drainage basin