The water cycle and water insecurity Flashcards
Breakdown of Earth’s water
-97% saltwater
-2.5% freshwater
-99% of freshwater is glaciers and ground water
Blue water
Stored in lakes, rivers, sea
Green water
Stored in soil and plants
Fossil water
Stored underground for over 10,000 years
Biggest water stores (km^3)
-Sea 1,300,000
-Glaciers 24,000
-Groundwater 23,000
Biggest water fluxes (km^3 /year)
-Evaporation 500
-Precipitation 500
Drainage basin
The area of land drained by a particular river network
Watershed
The boundary of a drainage basin
Factors affecting discharge of river and shape of hydrograph
-Basin size/shape/relief
-Permeability
-Vegetation
-Land use
-Precipitation & evapotranspiration rates
Amazon characteristics
-Four month lag time
-Constant convection rainfall
-High evapotranspiration
Indus characteristics (Pakistan/China)
-Peak discharge reached in April from snowmelt
-Monsoons June-Sept
-Rapidly dropping discharge in winter as water freezes
Yukon characteristics
(Alaska)
-Snow and permafrost melt in short summer
-Low discharge in winter
Pluvial & fluvial floods
Pluvial- Short lived, intense rain
Fluvial- Lag time
Physical factors of Sedgemoor floods 2013/2014
-One of flattest and lowest areas
-Steep surrounding uplands
-Low pressure system in Dec
-High tide stops rivers draining flood water
Human factors of Sedgemoor floods 2013/2014
-Budget cuts meant rivers weren’t dredged
-Housing & industrial developments (Morrisons depot in Bridgewater)
-Channel straightening
Causes of drought
-High pressure systems
-El-Nino Southern Oscillation
-Over extraction of groundwater
La Nina
Intensification of normal conditions. Low pressure in Australasia and high pressure in S.America
El Nino
Reversal of normal conditions. High pressure in Australasia and low pressure in S.America
Aridity
Permanent low precipitation (deserts)
Desertification
-Human induced
-Overgrazing and excessive water extraction
Benefits of wetlands
-Protects against flooding
-Purifies water
-Habitat for endangered species
-Carbon store
Uncertainty of impact of climate change on hydrological cycle
-Locations of rain belts and deserts may shift
-May be increased plant growth
-Effects on ENSO cycles unknown
-Loss of glaciers, nearly 1 billion people rely on meltwater
Future water scarcity
-Booming demand for food
-Increasing energy demand
-Climate change
-Water pollution
Virtual water
The water used to produce products, that we indirectly consume
Mexico City water insecurity
-Ageing infrastructure leaks 40% of water
-21.7m people
-Extraction of groundwater, causing the city to sink and damaging pipes
-Families spend 20% of income on bottled water
Lake Chad water insecurity
-Has dried by 90% in last 60 years
-High, growing agriculture usage
-Lifeline to 40m
California water insecurity
-Saltwater intrusion
-Lack of rain
-Over extraction of groundwater
-Wells created to try and create barrier against saltwater
Ethiopia stance on Nile
-Building largest dam in Africa
-Wants to provide electricity for population and exports
Sudan stance on Nile
-Historically sided with Egypt
-Renaissance dam will create constant Blue Nile flow
-To increase agriculture
Egypt stance on Nile
-Relies entirely on Nile for water
-Will expect less water because of dam, could kill 50% of farmland
-Evaporation is lower in Ethiopia so could increase supply in long term
Nile Basin characteristics
-White Nile has constant discharge
-Blue Nile peaks in summer
-Monsoon rains in summer
-Ethiopian highlands
-Sudd region - swamp
-Lake Victoria supplies White
Nile Basin Initiative
-1999, 10 countries
-Needed for rapidly growing population and conflict
-Not a legal framework, just a guide for alignment of water policies
Artificial Glaciers in Ladakh, Nepal
-Over 14% of glaciers lost in last 50 years
-Meltwater is redirected via pipeline and sprinkled over bushes, so it freezes
Cryosphere
All water in a frozen state
Smart irrigation
Providing crops with less than optimal supply, so that they are more resistant to droughts
