Assess the impacts of climate change on the flows(processes) in the
hydrological cycle (12 marks)
Climate change, primarily driven by human activities such as fossil fuel
combustion and deforestation, significantly alters the hydrological cycle. This
cycle involves various interconnected processes, including evaporation,
precipitation, infiltration, runoff, and groundwater flow.
The most significant factor that is being affected by climate change is snow melt.
Warming temperatures lead to changes in snow and ice dynamics, including
earlier snowmelt and reduced snowpack. This affects river flows, particularly in
regions that rely on snowmelt for freshwater supply during dry seasons. For
example, in the Himalayas, glaciers are a critical water source for billions of
people. As temperatures rise, glacial melt is accelerating, leading to an initial
increase in river flows. However, this is unsustainable, as glaciers continue to
shrink. Studies suggest that by the end of the century, the Himalayas could lose
up to 80% of their glaciers, threatening water availability for countries like India,
Pakistan, and Bangladesh. The loss of snowpack also impacts ecosystems
dependent on consistent water flows, affecting agriculture and increasing
competition for dwindling resources. All of these factors clearly demonstrate the
large impact that climate change has on flows in the hydrological cycle
Climate change is causing shifts in global precipitation patterns, with some
regions experiencing increased rainfall while others suffer from prolonged dry
spells. These changes are linked to warming temperatures and altered
atmospheric circulation patterns, leading to more extreme weather events. For
example the IPCC reports indicate that the tropics and subtropics are seeing an
increase in heavy rainfall events, with regions like Southeast Asia experiencing
intensified monsoons. Conversely, mid-latitude areas, including parts of Europe
and North America, are facing decreased precipitation and longer dry periods.
For instance, California has experienced severe drought conditions over the past
decade, leading to water shortages, increased wildfire risks, and significant
agricultural impacts. These alterations not only threaten water supply but also
disrupt ecosystems and biodiversity as species struggle to adapt to new
hydrological conditions. All these components demonstrate the large impact that
climate change has on flows in the hydrological cycle.
Finally ,as global temperatures rise, the rate of evaporation from rivers, and land
surfaces increases. Warmer air holds more moisture, leading to higher
evaporation rates. This phenomenon is particularly pronounced in regions
experiencing higher temperatures due to climate change. For Example according
to the World Meteorological Organization, evaporation rates have risen by
approximately 10% over the past few decades. In Southern Africa, where water
resources are already constrained, increased evaporation has exacerbated
drought conditions. During the 2015-2016 El Niño event, countries such as
Zimbabwe and Malawi faced severe water shortages, impacting agriculture and
drinking water supplies. The increase in evaporation not only reduces available
water but also affects local weather patterns, creating feedback loops that can
lead to more intense droughts. All of the factors show the impact that climate
change has on the flows in the hydrological cycle
In conclusion, there are many factors that climate change has a large impact on
however the most significant is the snow melt this is because it is a long term
impact and will have a large impact as more time passes whereas precipitation
,and evaporation rates are more short term and in the long run will have a less
crucial impact.
Evaluate the view that land use changes are the main cause of the increasing risk of river flooding (20)
The most significant land use change which causes an increased amount of flooding is urbanisation.
Urbanisation leads to decreased infiltration and interception and more surface runoff as it creates
more impermeable surfaces (e.g. concrete) and less permeable surfaces (e.g. soil and
grass).Furthermore, increased surface runoff leads to more overwhelmed drainage systems and
therefore more flooding. For example in London the Thames Barrier has seen increased flood risk
due to rapid urbanisation. Moreover, In Manchester heavy rainfall events have caused increased
flooding due to inadequate drainage systems (because of urbanisation and therefore more surface
runoff and more overflowed drainage systems).Additionally, in Paris urbanisation has reduced the
city’s ability to manage floodwaters leading to the 2016/2018 floods where the river Seine
overflowed due to heavy rainfall damaging infrastructure and displacing millions. All of these factors
demonstrate how the land use change of urbanisation can lead to river flooding and its importance.
Another land use change which has been influential in increasing the risk of river flooding is
deforestation. Deforestation reduces the capacity of forests to intercept water, promote infiltration
and reduce the flow of water in the river systems. When forests are destroyed, more water runs
directly off the floor, increasing the peak discharge and the chance of the river flooding, this is
particularly problematic in areas where the trees act as natural flood buffers. For example, in
Bangladesh extensive deforestation in the Ganges has increased flooding, one of the reasons is
because when deforestation occurs upstream it causes more river flooding downstream. The
increased river flooding causes more soil erosion which in turn decreases the river capacity to hold
water, creating even more flooding. In Bangladesh 37% of the land has already been submerged
demonstrating the drastic effects of river flooding. All of these factors demonstrate how the land use
changes of deforestation can lead to river flooding.
Another land use change is the use construction of dam however usually these help decrease the risk
of flooding instead. For example, the three Gorges Dam in China has significantly helped reduce river
flooding as it is the largest hydroelectric dam in the world and it has a massive reservoir that takes in
approximately 22 cubic kilometres of water per year. Furthermore the dam allows for the controlled
network of water smoothly, e.g. in 2020 the area near the dam had the largest rainfall ever recorded
but due to the dam effectiveness and network many cities such as Wuhan were saved due to the
river. Additionally there have been instances to prove that without it there would have been much
more increased amounts of flooding. For example in 1998 (before the dams construction) the
Yangtze River had a large flooding event which killed over 4000 people and displaced millions.
Whereas in 2010 (after the dams construction) the same river had a very similar amount of rainfall
but the impacts were severely reduced compared to the 1998 flooding. All of these factors
demonstrate how land use changes can actually help decrease the risk of flooding instead of
increasing it.
Finally there are also factors which increase the risk of river flooding which aren’t land use changes.
The most significant one is climate change as it increases the frequency and intensity of extreme
weather events such as flooding. Additionally, for every 1°C rise in temperature, the atmosphere can
hold approximately 7% more water vapour, leading to heavier downpours making climate change an
increasingly more dangerous threat to flooding. For example in the 2019 Mississippi river flooding
which was the worst river flooding the river had ever seen. The basin experienced flooding for over
200 consecutive days in some locations (the longest duration in recorded history). From March to
, May, the basin received more than 200–300% of average rainfall, and the Midwest experienced its
wettest 12 months since 1895, highlighting the intensification of precipitation patterns. A key driver
was rapid snowmelt, which occurred earlier and more intensely due to unseasonably warm spring
temperatures — a direct consequence of climate change. This surge in meltwater, combined with
saturated soils and persistent rainfall, overwhelmed the river’s capacity. The event caused an
estimated $20 billion in damages, particularly to agriculture, as over 19 million acres of farmland
were left unplanted. This case powerfully illustrates how climate change amplifies natural processes,
turning seasonal variability into extreme and sustained flooding.
In conclusion land use changes are very significant in increasing the risk of river flooding specifically
in regard to deforestation and urbanisation which both have drastic impacts that directly lead to
flooding. However due to the fact that land use changes can also decrease the risk of river flooding in
certain situations (e.g. because of dams) I can conclude that land use changes are not the primary
cause of increased river flooding. Instead climate change is the main cause of increased river flooding
due to its ability to amplify and intensity precipitation patterns and that in the future it continues to
be an ever growing threat which will only increase flooding further.
hydrological cycle (12 marks)
Climate change, primarily driven by human activities such as fossil fuel
combustion and deforestation, significantly alters the hydrological cycle. This
cycle involves various interconnected processes, including evaporation,
precipitation, infiltration, runoff, and groundwater flow.
The most significant factor that is being affected by climate change is snow melt.
Warming temperatures lead to changes in snow and ice dynamics, including
earlier snowmelt and reduced snowpack. This affects river flows, particularly in
regions that rely on snowmelt for freshwater supply during dry seasons. For
example, in the Himalayas, glaciers are a critical water source for billions of
people. As temperatures rise, glacial melt is accelerating, leading to an initial
increase in river flows. However, this is unsustainable, as glaciers continue to
shrink. Studies suggest that by the end of the century, the Himalayas could lose
up to 80% of their glaciers, threatening water availability for countries like India,
Pakistan, and Bangladesh. The loss of snowpack also impacts ecosystems
dependent on consistent water flows, affecting agriculture and increasing
competition for dwindling resources. All of these factors clearly demonstrate the
large impact that climate change has on flows in the hydrological cycle
Climate change is causing shifts in global precipitation patterns, with some
regions experiencing increased rainfall while others suffer from prolonged dry
spells. These changes are linked to warming temperatures and altered
atmospheric circulation patterns, leading to more extreme weather events. For
example the IPCC reports indicate that the tropics and subtropics are seeing an
increase in heavy rainfall events, with regions like Southeast Asia experiencing
intensified monsoons. Conversely, mid-latitude areas, including parts of Europe
and North America, are facing decreased precipitation and longer dry periods.
For instance, California has experienced severe drought conditions over the past
decade, leading to water shortages, increased wildfire risks, and significant
agricultural impacts. These alterations not only threaten water supply but also
disrupt ecosystems and biodiversity as species struggle to adapt to new
hydrological conditions. All these components demonstrate the large impact that
climate change has on flows in the hydrological cycle.
Finally ,as global temperatures rise, the rate of evaporation from rivers, and land
surfaces increases. Warmer air holds more moisture, leading to higher
evaporation rates. This phenomenon is particularly pronounced in regions
experiencing higher temperatures due to climate change. For Example according
to the World Meteorological Organization, evaporation rates have risen by
approximately 10% over the past few decades. In Southern Africa, where water
resources are already constrained, increased evaporation has exacerbated
drought conditions. During the 2015-2016 El Niño event, countries such as
Zimbabwe and Malawi faced severe water shortages, impacting agriculture and
drinking water supplies. The increase in evaporation not only reduces available
water but also affects local weather patterns, creating feedback loops that can
lead to more intense droughts. All of the factors show the impact that climate
change has on the flows in the hydrological cycle
In conclusion, there are many factors that climate change has a large impact on
however the most significant is the snow melt this is because it is a long term
impact and will have a large impact as more time passes whereas precipitation
,and evaporation rates are more short term and in the long run will have a less
crucial impact.
Evaluate the view that land use changes are the main cause of the increasing risk of river flooding (20)
The most significant land use change which causes an increased amount of flooding is urbanisation.
Urbanisation leads to decreased infiltration and interception and more surface runoff as it creates
more impermeable surfaces (e.g. concrete) and less permeable surfaces (e.g. soil and
grass).Furthermore, increased surface runoff leads to more overwhelmed drainage systems and
therefore more flooding. For example in London the Thames Barrier has seen increased flood risk
due to rapid urbanisation. Moreover, In Manchester heavy rainfall events have caused increased
flooding due to inadequate drainage systems (because of urbanisation and therefore more surface
runoff and more overflowed drainage systems).Additionally, in Paris urbanisation has reduced the
city’s ability to manage floodwaters leading to the 2016/2018 floods where the river Seine
overflowed due to heavy rainfall damaging infrastructure and displacing millions. All of these factors
demonstrate how the land use change of urbanisation can lead to river flooding and its importance.
Another land use change which has been influential in increasing the risk of river flooding is
deforestation. Deforestation reduces the capacity of forests to intercept water, promote infiltration
and reduce the flow of water in the river systems. When forests are destroyed, more water runs
directly off the floor, increasing the peak discharge and the chance of the river flooding, this is
particularly problematic in areas where the trees act as natural flood buffers. For example, in
Bangladesh extensive deforestation in the Ganges has increased flooding, one of the reasons is
because when deforestation occurs upstream it causes more river flooding downstream. The
increased river flooding causes more soil erosion which in turn decreases the river capacity to hold
water, creating even more flooding. In Bangladesh 37% of the land has already been submerged
demonstrating the drastic effects of river flooding. All of these factors demonstrate how the land use
changes of deforestation can lead to river flooding.
Another land use change is the use construction of dam however usually these help decrease the risk
of flooding instead. For example, the three Gorges Dam in China has significantly helped reduce river
flooding as it is the largest hydroelectric dam in the world and it has a massive reservoir that takes in
approximately 22 cubic kilometres of water per year. Furthermore the dam allows for the controlled
network of water smoothly, e.g. in 2020 the area near the dam had the largest rainfall ever recorded
but due to the dam effectiveness and network many cities such as Wuhan were saved due to the
river. Additionally there have been instances to prove that without it there would have been much
more increased amounts of flooding. For example in 1998 (before the dams construction) the
Yangtze River had a large flooding event which killed over 4000 people and displaced millions.
Whereas in 2010 (after the dams construction) the same river had a very similar amount of rainfall
but the impacts were severely reduced compared to the 1998 flooding. All of these factors
demonstrate how land use changes can actually help decrease the risk of flooding instead of
increasing it.
Finally there are also factors which increase the risk of river flooding which aren’t land use changes.
The most significant one is climate change as it increases the frequency and intensity of extreme
weather events such as flooding. Additionally, for every 1°C rise in temperature, the atmosphere can
hold approximately 7% more water vapour, leading to heavier downpours making climate change an
increasingly more dangerous threat to flooding. For example in the 2019 Mississippi river flooding
which was the worst river flooding the river had ever seen. The basin experienced flooding for over
200 consecutive days in some locations (the longest duration in recorded history). From March to
, May, the basin received more than 200–300% of average rainfall, and the Midwest experienced its
wettest 12 months since 1895, highlighting the intensification of precipitation patterns. A key driver
was rapid snowmelt, which occurred earlier and more intensely due to unseasonably warm spring
temperatures — a direct consequence of climate change. This surge in meltwater, combined with
saturated soils and persistent rainfall, overwhelmed the river’s capacity. The event caused an
estimated $20 billion in damages, particularly to agriculture, as over 19 million acres of farmland
were left unplanted. This case powerfully illustrates how climate change amplifies natural processes,
turning seasonal variability into extreme and sustained flooding.
In conclusion land use changes are very significant in increasing the risk of river flooding specifically
in regard to deforestation and urbanisation which both have drastic impacts that directly lead to
flooding. However due to the fact that land use changes can also decrease the risk of river flooding in
certain situations (e.g. because of dams) I can conclude that land use changes are not the primary
cause of increased river flooding. Instead climate change is the main cause of increased river flooding
due to its ability to amplify and intensity precipitation patterns and that in the future it continues to
be an ever growing threat which will only increase flooding further.
