THE WATER CYCLE AND WATER INSECRITY
EXAM WITH QUESTIONS AND WELL VERIFIED
ANSWERS [GRADED A+] ACTUAL EXAM 100%
What is meant by a store and a flow? -
... [Show More] ANS✔✔---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 - ANS✔✔---1. The oceans
2. Icecaps and glaciers
3. Groundwater
Which two water stores are non-renewable, and why? - ANS✔✔---1. Fossil
water: old, deep groundwater from former wetter periods
2. Losses from the cryosphere: melting of ice as a result of global warming
Why is the hydrological cycle a closed system? - ANS✔✔---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? -
ANS✔✔---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
Distinguish between blue and green water - ANS✔✔---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
What are the main inputs of a drainage basin system? - ANS✔✔---
Precipitation. Also possibly water from a tributary basin
What are the main outputs of a drainage basin system? - ANS✔✔---
Evaporation, transpiration and river discharge
The steepness of slopes will affect the rate of runoff — the steeper the slope,
the faster the rate
Distinguish between interception and infiltration - ANS✔✔---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 relief affect the inputs and outputs of a drainage basin? -
ANS✔✔---Altitude will affect the precipitation input (orographic rain or snow).
How does geology affect the flows in a drainage basin? - ANS✔✔---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 how deforestation is affecting the Amazon basin - ANS✔✔---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
Distinguish between a water budget and a river regime - ANS✔✔---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? - ANS✔✔---It affects the amount of
precipitation received, while temperatures affect rates of evaporation and
transpiration
Name three other ways in which people disrupt the drainage basin cycle -
ANS✔✔---Urban growth; constructing dams and reservoirs; abstracting
water for irrigation
Identify three physical factors affecting a river's regime - ANS✔✔---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? - ANS✔✔---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? - ANS✔✔---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
Why does urbanisation increase the risk of flooding? - ANS✔✔---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
Identify three symptoms of hydrological drought besides dried-out water courses
- ANS✔✔---1. Stressed or dead vegetation
2. Soil erosion
3. Abandoned cultivation plots
How does geology affect the shape of a storm hydrograph? - ANS✔✔---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 lon [Show Less]