the water cycle

Question 1

describe the water cycle

Answer 1

the water cycle is a closed system with stores and transfers operating between the cryosphere, hydrosphere, biosphere, lithosphere and atmosphere. Almost 97 percent of the worlds water is tores within the oceans and seas however only 3 percent of this is fresh water. Within this 3 percent, the majority of freshwater is locked up in glaciers.

Question 2

why are there concerns about safe potable water?

Answer 2

only 3 percent of the worlds water is freshwater with 69 percent of this water being locked up in ice or glacier
the cryosphere has experienced depletion over years therefore mixing the freshwater sources with salt water
this means there is a decreasing level of potable water as salt water is inadequate for human consumption without desalination at high costs

Question 3

define sublimation

Answer 3

conversion between solid to gas without becoming a liquid

Question 4

define ablation

Answer 4

the removal of snow and ice from a glacier or iceberg by melting or evaporation

Question 5

explain the role of cryospheric changes in the water cycle

Answer 5

• the cryosphere is a major water store
• in a period of cooling the cryosphere will grow in size due to accumulation but when there is a period of warming the cryosphere will add to the water cycle as the ice undergoes ablation, returning the water to the sea. this results in rising sea levels
• overall cryospheric processes have a regulatory role in sea levels

Question 6

outline ice formation

Answer 6

• snow falls as flakes
• snow accumulates
• compression of lower layers by the upper layers turns snow into a more compact form
• melt water seeps into gaps and then freezes, further compacting mass
• air is squeezed out of lower snow due to the weight of upper layers
• after periods of years a solid ice mass is formed. which can develop into a glacier if it becomes large enough

Question 7

define accumulation

Answer 7

the build up of a glacier due to the input of snow which is compacted into ice

Question 8

outline flows within the water cycle operating on a hill slope

Answer 8

• infiltration occurs when the water moves from the surface and down through the soil until is reaches the groundwater. the infiltration capacity refers to how quickly infiltration occurs for example tree roots create passages for water to flow through thus increases the infiltration capacity.
• surface runoff occurs when water runs directly over the ground which might occur when the soil is saturated or there are impermeable surfaces
• groundwater flow is when water moves through impermeable rock under the force of gravity which is the slowest flow of water on a hill slope

Question 9

outline an example of a positive feeback loop in the water cycle

Answer 9

• increased global temperatures result in increased melting of the snow and ice
• this causes a reduction of surface albedo due to a decrease in the amount of white surfaces
• this means that more sunglight is absorbed by the land and the sea instead of being reflected to back
• this causes the global tempeartures to increase further which causes greater mleting of the snow and ice

Question 10

outline the water balance equation

Answer 10

P= Q + E +/- S
P=precipation 
Q = total run off
E= Evapotranspiration 
S = storage

Question 11

what anthropogenic factors influence the water cycle along a river

Answer 11

• the rising world population has increased the demand for urban growth. more urbanised areas increased the regions of land which are built upon with settlements and infrastructure which is composed of impermeable materials. these materials prevent infilitration of water and thus increases the rate of overland flow
• deforestation causes a reduction in interception so more water reaches the ground to be transported in overland flow
• agriculutral practices like livestock farming causes the comapction of the soils which reduced the infiltration into the ground and increases overland flow
• water abstraction is required as a supply for farming crops and other agriculutral processes. this reduces the base flow which means that more water must reach the river channel before it reaches its capacity

Question 12

what physical factors influence the water balance

Answer 12

• if the drainage basin shape is circular in shape it means that each point in the basin is roughly equidistant from the emasuring point of the river so the water enters the river at similar times
• if the geology of the land is composed of impermeable rock this prevents water from being able to infilitrate the ground thus icnreaseing overland flow whereas porour rocks means water can infiltrate
• if the vegetation cover of the basin is dense the vegetation will be able to intercept the rainwater. if the vegetation is majoritally deciduous trees they will drop their leaves in the winter months thus decreaseing interception
• heavy or prolonged rainfall will cause the ground to become saturation to its infilitration capacity which will decrease the infilitration rates and increase the volume of surface run off

Question 13

The River Tyne Case Study

Answer 13

• located in the north east of England spanning 73 miles until it enters into the North Sea
• the geology of the land around River Tyne consists of rocks from the carboniferous period which are hard sedimentary rocks
• the upper course in rural areas in Northumberland is mostly used for commercial farming
• the land in the lower course is utilised for housing and industries

Question 14

describe the location of the amazon rainforest

Answer 14

the amazon rainforest is located within the Amazon river basin in South America. It covers alomst 8 countries including Brazil and Peru. It is situated a few degrees south of the equator.

Question 15

why is the amazon rainforest significant?

Answer 15

• the amazon rainforest is home to 20 percent of the species located on earth with it containing 10 million species of insects and 1000 species of birds.
• it is home to 20 million people

Question 16

how has deforestation impacted the amazon rainforest?

Answer 16

• the amazon rainforest has experiences a rapid increase in the rates of deforestation which is greatly attributed to a growing global population over recent years which means greater demand for resources. this means the removal of trees is occuring due to agricultural processes, logging, and settlement growth.
• the wwf predicts that 27 percent of the amazon biome will be without trees if the current rates of deforestation occur by 2030
• in the rainforest, the vegetation contributes to moisture in the atmosphere as water transpires and evaporates from their leaves. The moisture in the atmosphere attributes to the formation of clouds which release water back onto the rainforest. this moisture can travel globally influencing rain patterns in south eastern europe and china. through the removal of the trees the rate of evapotranspiration has declined, with the forest flux rate of transpiration falling by 1km3 per year over the decade. this has lead to a less humid environment. overall, there is reduction in rainfall which promotes droughts and desertification to occur. through a rise in drought periods, the trees which were suited to the humid and wet conditions, promoting photosynthesis, will deteriorate. Previously these plants would absorb carbon dioxide in the process of photosynthesis however as this declines they are transformed from a carbon sink to a carbon source as they decompose, releasing carbon dioxide into the atmosphere.
• with fewer trees due to deforestation, most of the precipitation will reach the ground immediatley, saturating it and encouraging overland flow. this cause a rise in the flash floods as there is less forest cover to intercept any rainfall. moreover, the higher rates of surface run off will contribute to increased dorught periods as the water is rapidly removed from the rainforest by surface run off. this can result in a higher risk of wildfire occurences.

Question 17

define river flow

Answer 17

is the volume of water passing a measuring point in a given time
discharge (m3 per second) = cross sectional area (m2) x velocity (m/s)