The Water Cycle And Water Insecurity Exam Style Questions And Answers

The Water Cycle And Water Insecurity Exam Style Questions And Answers

Describe how deforestation is affecting the Amazon basin - The amount of water 
returning to the atmosphere by evapotranspiration is greatly reduced — from 
75% to 25% of intercepted water. More precipitation enters the river by runoff. 
Overland flow increases the amount of soil erosion. Huge quantities of soil are 
entering the rivers and causing extensive silting. Mudslides are increasing in 
frequency and scale. The flood risk is raised by the faster runoff. Aquifers are 
becoming depleted because less water infiltrates to recharge them
Name three other ways in which people disrupt the drainage basin cycle - Urban 
growth; constructing dams and reservoirs; abstracting water for irrigation
Distinguish between a water budget and a river regime - Water budget is the 
difference between precipitation and evapotranspiration, which varies from place 
to place and seasonally. River regime is the seasonal variation in the discharge or 
flow of a river and it too varies, but from drainage basin to drainage basin
How does climate affect water budget? - It affects the amount of precipitation 
received, while temperatures affect rates of evaporation and transpiration
Identify three physical factors affecting a river's regime - Amount and intensity of 
precipitation; geology and soils; vegetation cover
How do you explain the seasonal variations in runoff when rainfall is evenly 
distributed throughout the year? - The lower runoff during the summer and early 
autumn is due to the higher temperatures and high water losses due to 
evapotranspiration. Also the dry ground means that much of the rain infiltrates 
and percolates below ground
What is a storm hydrograph? - A storm hydrograph shows the response of a 
river's discharge following a period of rainfall. A critical aspect of the hydrograph 
is the lag time between the rainfall peak and the river's peak discharge
How does geology affect the shape of a storm hydrograph? - If the geology is hard 
and impervious, then the speed of runoff will be such as to result in a relatively 
short lag time. If the geology is soft and porous, then runoff will be less and the 
water will reach the river more slowly as it takes place below ground. The lag time 
will be relatively long
Why does urbanisation increase the risk of flooding? - The large areas of concrete 
and tarmac mean that most falling rain becomes surface runoff which moves 
quickly to the nearest stream or river. Underground drains and sewers also move 
water quickly to drainage channels. Because of this swift transfer of water, rivers 
quickly reach the bank-full stage and water begins to overspill their channels as 
floods
What is meant by a store and a flow? - A store is where water is held for varying 
amounts of 'residence' time. A flow is the movement of water between stores
Identify the three largest stores in size order - 1. The oceans
2. Icecaps and glaciers
3. Groundwater
Which two water stores are non-renewable, and why? - 1. Fossil water: old, deep 
groundwater from former wetter periods
2. Losses from the cryosphere: melting of ice as a result of global warming
Distinguish between blue and green water - Blue water is stored in rivers, lakes 
and groundwater in liquid form — a visible part of the hydrological cycle. Green 
water is water stored in the soil and vegetation — an invisible part of the 
hydrological cycle
Why is the hydrological cycle a closed system? - There are no external inputs and 
outputs. It is a self-contained entity. Some might argue solar energy, which drives 
the cycle, is an input
What is the water budget, and why does it vary from place to place? - The water 
budget of a place is the difference between the amount of water gained from 
precipitation and the amount lost as a result of evapotranspiration. The budget is 
in surplus when precipitation exceeds evapotranspiration. It is in deficit when the
situation is reversed. It varies from place to place because climate (precipitation 
and temperature) does
What are the main inputs of a drainage basin system? - Precipitation. Also 
possibly water from a tributary basin
What are the main outputs of a drainage basin system? - Evaporation, 
transpiration and river discharge
How does relief affect the inputs and outputs of a drainage basin? - Altitude will 
affect the precipitation input (orographic rain or snow). The steepness of slopes 
will affect the rate of runoff — the steeper the slope, the faster the rate
Distinguish between interception and infiltration - Interception is the process by 
which water is stored in the vegetation. Infiltration is the process by which water 
soaks into, or is absorbed by the soil
How does geology affect the flows in a drainage basin? - Geology affects the 
balance of the flows by which precipitation reaches a river. Where the geology is 
hard and impermeable (e.g. granite), there will be much surface runoff and 
relatively little infiltration and percolation. Where rock is porous, then the balance 
will be the reverse with little runoff and much percolation and water reaching the 
river via through flow and groundwater flow
Describe three different ways of conserving water - More efficient use of 
irrigation water; greater use of grey water; filtration technology; water metering