water case studies Flashcards
(38 cards)
How have humans disrupted the Amazonia drainage basin
- deforestation - destroys natural habitat of countless species and contributed to climate change
- industrial development - mining and oil drilling - lead to water pollution , soil erosion , destruction of animal and plant life
contructtion of infrastructure can disrupt flow of water and nutrients
Climate change - lead to more frequent wildfires and changing rainfall patterns
what have been the impacts of human disruption to the amazon drainage basin
- loss of millions of hectares of forests - loss of habitat leading to exctintion of many species and dirsuption of ecosystems
- amazon forest is becoming drier and more vulnerable to fire
- less rainfall leading to possible droughts and floods
- water pollution
- loss of biodiversity
- threats to indigenous communities who rely on the rainforest for their livelihoods and cultural tradition
what does the water budget in a tropical climate look like
- characterised by high levels of precipitation and EVT
- due to warmer temps higher humidity aswell as presence of rainforests and other vegetation that help to generate and retain moisture
why is EVT high in tropical climates
warm temps and high humidity create ideal conditions for plant growth and water reuptake - as a result precipitation is quickly taken up by plants and returned to the atmosphere through transpiration
how can the water budget in tropical climates be innfluenced
- soil type , topography and human activity
- deforestation can reduce EVT and increase runoff - lead to changes in local water cycle anf affect downstream resources
- land use changes - agriculture and industry can lead to pollution and overuse of water resources
what does the water budget in a polar climate look like
- dominated by freezing and melting of sea ice
- due to low temps and limited precip amount of water available is very low
- so water budget largely determined by exchange of water between the atmosphere ocean and cryosphere
what does precipitation , evaporation and runoff look like in a polar water budget
precipitation- relatively low - mostly falls as snow
evaporation- low due to cold temps and low humidity
runoof- limited - can occur as either liquid water or as meltwater from glaciers and sea ice
change in water storage is largely determined by the melting and freezing of sea ice and glaciers
what impacts are there on a polar water budget
changes in temp and precip patterns can have significant impacts and can contribute to changes in sea level and ocean circulation patterns
what are the differences between the Yukon river regime and the Amazon river regime
Amazon -
- has a wet season (december to june) where rainfall and snow melt from the andes causes a large increase in river flow
- has a dry season (july to nov) where the flow rate decreases due to reduced rainfall and increased evaporation
Yukon
- seasonal melt of snow and ice
- highest water levels during spring and summer - highest in late june early july
what are the reasons for the differences between the Yukon and the Amazon river regimes
climate -
- amazon - has a tropical monsoon climate - receives large amount of rainfall
- yukon - subartic climate - much lower annual precip mostly in form of snow
Geology -
amazon - dominated by sedimentary rocks - porous and allow for rapid infiltration and runoff
- has extensive wetlands and floodplains that store water and regulate discharge
- Yukon- crystalline rocks - relatively impermeable and store water in glaciers and snowpacks
- has extensive perma frost - limits infiltration rates and contributes to t surface runoff during spring and summer
Soils -
- amazon - has soils that have low water holding capacity and limited permeability which can lead to rapid runoff - has wetlands and floodplains to help counter act that
- Yukon - has soils with high water holding capacity - soils store water as snow and ice during winter and release during spring and summer - permafrost limits the infiltration into the soil so surface runoff during winter
what are some facts ( a few ) about the droughts in Australia
30% of the country usually affected in any one year
the big dry of 2006 covered large areas of australia for several years
the big dry was assessed as a 1 in 1000 year event
what are some physical reasons for drought in Australia
- low highly variable rainfall because of the sub tropic high pressure belt
- most closely linked to el nino events
- since the 1970s there has been a shift in rainfall patterns in the eastern area where most people live
- the big dry was thought to be associated with longer term climate change leading to a trend of a warmer drier climate for south eastern Australia
what are the impacts of the droughts in Australia
- the big dry affected more than half the farmlands especially in the murray darling basin which provides 50% of the nations agricultural outputs - impacts on wool and food supplies , wheat and meat exports
- farmers also relied on water for irrigation of rice cotton and fruit farms
- reservoirs fell to 40% of their capacity
- bushfires more common - people and animals lost property and lives
- rivers dried up and loss of fish populations
what were some human impacts that makes the sahelian region prone to drought
- air pollution from europe and north america cooled the earth , preventing tropical rains moving northwards
- higher sea temps from global warming prevented moist atlantic air moving over western sahel
- desertification has resulted from overuse of land due to population pressures
What happened during the UK flood events from 2015-2016
- during the winter of 2015-16 northern parts of the uk were affected by a sequence of depressions (low pressure systems) , each providing periods of prolonged intense heavy rainfall
what were some examples of the different flood events in the UK 2015-16
Storm abigail in november saturated soils
- storm desmond in december caused flooding in cumbria with over a months rainfall in one day (convectional, orographic and frontal)
- storm eva caused flooding over the pennines
- storm frank in western areas
what were some socio- economic impacts of the uk 2015-16 flood events
- over 16,000 properties over the uk were flooded
- uk government provided 200 million for flood recovery
- estimated total economic costs at 5 billion
- consumers and deliveries unable to reach businesses
- people evacuated
- deaths
- sediment deposited in houses
- schools closed
- roads and railways blocked
what were some environmental impacts from the UK flood events in 2015-16
- erosion of rivers and coastal areas
- soil degradation and erosion in agricultural areas
- loss of habitats
- ## flood waters picked up pollutants such as chemicals and sewage pose a risk to environment and human health
what is an example of a place facing climate variability and increasing risk of water insecurity
the UK - having wetter winters but drier summers
- influenced by the North Atlantic Ocean, which circulates warm water from the tropics towards the Arctic and cold water back towards the equator
- also influenced by atmospheric circulation patterns, such as the North Atlantic Oscillation (NAO), which is a natural cycle that affects the strength and position of the jet stream.
what is an example of a place facing salt water encroachment and at an increased risk of water insecurity
The mekong delta in vietnam
- sea level rise is pushing salt water higher upstream and infiltrating freshwater aquifers
- reduced sediment deposition from building dams upstream - delta has less sediment and is sinking so at risk further from encroachment
- over abstraction in aquifers
what is an example of a place where there has been over-abstraction of groundwater
Mexico city
- there has been an increase in groundwater abstraction due to an increase in population - led to ground subsidence
- over abstraction causes the water table to drop and the rock and sediment above the table to compress - causes surface land to sink
- mexico also built on an old lake bed - soft sediment more prone to compaction
what have been the impacts of land subsidence in mexico city
- led to damage to infrastructure e.g. in the 1970s a railways station had to be closed due to severe subsidence
- Land subsidence has reduced the capacity of drainage systems in Mexico City, leading to more frequent and severe flooding.
- rate of land subsidence in Mexico City has led to the loss of up to one meter of groundwater storage capacity per year
- the loss of wetlands, sinking of forested areas, and changes to river flow patterns.
-subsidence has caused damage to historic buildings and cultural heritage sites, posing a threat to Mexico City’s cultural identity.
what is an example of an area experiencing contamination from farming / industry
Animas river in colorado
- flows through the San Juan Mountains, an area with a long history of mining. Over time, mine waste has built up in the mountains, and when water comes into contact with the waste, it can become contaminated with heavy metals such as lead, cadmium, and arsenic.
- an environmental disaster occurred when a mine near Silverton, Colorado, released millions of gallons of wastewater into the Animas River
The contaminants were harmful to aquatic and human life , especially if they managed to get into water sources
why is there conflict at the Nile delta about usage
11 users
- vital source for Egypt and sudan
- ethiopia (upstream from these two) are building large hydroelectric dam (GERD)
Egypt concerned about the dam and how it might reduce flow downstream - this could impact agricultural production, food security and economy
- sudan have same concerns
- also environmental concerns - damage to ecosystems
- treaties have been signed but still conflict over water allocation and management of the basin as a whole
