water abstraction (ELSS) Flashcards
(25 cards)
Mexico City:
the capital and largest city in Mexico
North America’s most populous city
located in the Valley of Mexico or the Basin of Mexico
population is over 9 million so demand is very high –> population growth is a big problem
Mexico City:
use of water
the main use of water is for domestic purposes such as drinking, cooking, bathing & sanitation
industrial and agricultural purposes are also vital
around 60% of water comes from underground aquifers
Mexico City:
main source of water
residents rely heavily on the main H2O system- the Cutzamala System to provide clean water
Mexico City:
extraction
rate=53 m2/s
recharge rate=50 m2/s
Mexico City:
sinking
20 inches per year
severe depletion of groundwater leading to land subsidence
up to 30m in the next 150 years
Mexico City:
water scarcity is a significant issue due to
over extraction
the city relies heavily on ground water from aquifers which are depleted faster than they are being replenished
this is leading to drains in water levels
Mexico City:
water scarcity is a significant issue because
pollution
pollution means that water is being contaminated so it’s harder to access clean safe water
Mexico City:
water scarcity is a significant issue because
climate change
means that irregular rainfall affects the availability of water
droughts and extreme weather events can also exacerbate the situation
Saudi Arabia:
located in West Asia
centre of the Middle East
covers the bulk of the Arabian Peninsula
Saudi Arabia:
water comes from
-60% of drinking water comes from desalination
-40% from mining of non-renewable groundwater
-10% from surface water in mountains in SW
-annual precipitation is about 50mm/year –> doesn’t satisfy freshwater needs of the country
-most of the fossil groundwater is stored in aquifers in E/central (confined in sandstone and limestone up to 200m thick, 150-1500m deep)
Saudi Arabia:
desalination
-since the 1950s there has been a greater dependence on desalination
-takes 300000 barrels of oil daily to power SAs desalination plants –> leaves behind highly concentrated saline fluid –> raises levels of salt in seawater and potential danger to sea life
-9 million cubic metres by desalination in 2022
Saudi Arabia:
pressures
-when intensive farming started there was 500km2 of water beneath the Saudi desert but in recent years up to 21km2 has been pumped to the surface annually for use in farms- none is replaced due to no rain
-4/5 of the saudis “fossil” water is now gone
-87%of water is used for agriculture
-by 2040 the population is projected to expand by 2.3% or to 42 million people putting water supply under more strain
Saudi Arabia:
aquifers
-the main aquifers are all hydrologically linked to one another and they are mainly found in the NE of the country
-they have overrelied on the groundwater aquifers meaning they have now gone to using sea water
-the Mega Aquifer System (MAS) has an area of 1860000 km2
Saudi Arabia:
soil compaction
soil salinisation is affected by the low levels of groundwater as it compacts together –> negative for agricultural production
River Kennet:
-located in Reading,Berkshire Uk
-measures up to 40-44km wide and 5ft deep –> one of the largest tributaries of the River Thames
-one of Englands most important chalk streams
-Thames Water built pipeline in 2017 to reduce capacity of destruction in times of low flow
River Kennet:
uses
-fishing is the main use
-industrial use and power mills on strong flows of water
-17th/18th century –> tanning and brewing
-water extracted during the 1990s
River Kennet:
pollution
-in July 2013 a 10 mile stretch of river, between Hummberford and Marlborough suffered from chemical contamination from pesticide which affected a large number of invertebrates
-150000L of fuel leaked through storm drains into the river
River Kennet:
reduced river flows
groundwater extraction has lead to a net depletion of river flow downstream, with summer flows reduced by 10-14% on average and even more (up to 40% in some drought periods)
River Kennet:
lower groundwater levels
over abstraction has caused groundwater levels to fall resulting in a reduced recharge rate
this has led to a decrease in the amount of water available for the river impacting the aquatic environment
River Kennet:
reduced flooding
lower flows means less frequent and extensive flooding
the reduction in water levels also impacts the temporary areas of standing water and wetlands on the floodplain,which are important habitats
River Kennet:
impact on springs and seepages
lower groundwater levels have also dried up springs and seepages which are important sources of water and contribute to the natural flow of the river
River Kennet:
dried up river sections
the upper reaches of the River Kennet particularly near Marlborough College have dried up more frequently due to water abstraction
