Water and its management Flashcards
Describe the global water distribution
- 97% of the water is saline ( inconsumable )
- 2/3rd of the freshwater we can consume is locked in glaciers
- Rest stored as groundwater (water in the soil or water held in pores of rocks)
- Surface freshwater is barely 1%
Describe the water cycle
- The sun heats the water in rivers, lakes, etc, and it evaporates into water vapor + transpiration from plants
- This moist water vapor rises because its less dense and forms into clouds through condensation
- It then precipitates and intercepts for human survival or freezes into glaciers and ice caps
Most of the water however runs off the surface into rivers as groundwater flow or infiltrates the ground through percolation which is stored in aquifers
Define percolation
The downward movement of water from soil to rock
Define infiltration
The downward moment of water through the soil and into the rock layer below
Define aquifer
A layer of porous and permeable rock that stores underground water
Define groundwater flow
The movement of water through rocks
How is water extracted from aquifers?
Through an artesian well-
A pipe is drilled from the surface to the aquifer.
Natural pressure means water will flow up on its own without the need for external pumping- This is the case when there is an impermeable and non-porous rock layer such as clay under and below the aquifer (flowing artesian well)
Effects of groundwater depletion
- Wells dry up
- Larger pumps are required (more energy +costs) since the water depth increases
- Land collapse
- Saline contamination
What is the crisis faced with both sources of freshwater?
Groundwater depletion- This occurs when water is being pumped out at higher rates than the aquifer is being replenished by the surface runoff and percolation of rainwater.
Surface water depletion- When the dams/ reservoirs/ lakes are being used faster than the tributary streams, rain etc, is replenishing it
Describe desalination plants
They involve removing dissolved salt from seawater and brackish (slightly salty) water from places such as river estuaries as well as treating wastewater (sewerage) to make it reusable for drinking.
Why don’t all countries invest in desalination plants?
It’s incredibly expensive and highly unaffordable for LEDCS who require it the most. This is because there are high costs of production, the process is energy intensive and it requires building large processing plants
How can you tell a countries economic situation from their water consumption?
LEDCS tend to have a high percentage of consumption in the agriculture sector (MEDCS agriculture will be intensive and water efficient)
MEDCS has the highest industrial and domestic (wells vs washing machines)
Difference between physical and economic water scarcity
Physical- All available reserves of water have been exploited
Economic- When there is insufficient water despite adequate reserves available due to a shortage in capital, income to exploit it
Difference between potable and non potable water
Potable is water that has been treated to ensure it’s free from external contaminants and harmful bacteria, unlike non-potable water which is extracted directly from wells, rivers, and lakes most likely contaminated by feces causing chronic diarrhea, and bacterial diseases like typhoid or viral infections like hepatitis A.
Difference between + Example-
- waterborne
- water bred
- water related
- Waterborne:
A disease caused by pathogenic microorganisms that are transmitted in contaminated freshwater - Water bred: Malaria
When the parasite breeds in water - Water related