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Water Resources and Usage (Ground water and Aquifers (Some precipitation…
Water Resources and Usage
Freshwater use and availability
Scarce resource: 0.024 of the water supply is readily available to us as liquid freshwater stored in lakes, rivers, streams, springs, and caves.
Begins to fail when: overload with water pollutants
withdraw freshwater from underground and surface water supplies faster than natural processes replenish it.
Freshwater is one of the Earth's most important forms of natural capital, but one of the most poorly managed.
ex. Failing water tables, shrinking lakes, disappearing wetlands
This also includes National and global security, Global Health, Equality and poverty
Virtual water: water that is not directly consumed but used to produce food and other products aka embedded water, makes up a large part of our footprints (especially in more developed countries)
Water is being evaporated more constantly which means the freshwater supply is getting smaller
Reducing Freshwater Use
How can we use
freshwater
sustainably
Reduce water waste in industries and homes: recycling industry water, reduce leaks, reduce toilet flush volume and shower times
Reduce water waste in irrigation: Use drip irrigation, irrigate at night, grow less thirsty crops, organic and polyculture farming to retain soil moisture
The most inefficient system commonly used in less developed countries is flood irrigation aka gravity flow irrigation
Regular spray irrigation
Most efficient is drip irrigation, aka micro-irrigation but it is expensive
Ground water and Aquifers
Some precipitation soaks into the ground and sinks downward through spaces in soil, gravel, and rock until an impenetrable layer of rock or clay stops it. The freshwater in these underground spaces is called groundwater.
The top layer of this is called water table.
An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt)
Can contain caverns with rivers of groundwater flowing
Most aquifers are like largely elongated sponges where groundwater seeps through porous layer of sand gravel or rock.
Unconfined and confined aquifer: are those into which water seeps from the ground surface directly above the aquifer.
Confined aquifer: are those in which an impermeable dirt/rock layer exists that prevents water from seeping into the aquifer from the ground surface located directly above.
Problems caused by overpumping aquifers: increasing poverty and civil unrest, inequality, saltwater seeping, land subsidence. Solutions can be: use water more effectively, subsidize water conservation, limit number of wells.
Increasing Freshwater Use: availabilty
Dams:
Dam and reservoir systems: capture and storethe surface runoff from a river's watershed
release it as needed to:
control floods generate electricity(hydropower), supply fresh water for irrigation and for towns and cities.
Problems with dams: downriver gets dramatic decrease in water
Upriver gets flooded
Reservoirs aren't useful for long
Water Transfer:
Governments have tried to solve water shortages by transferring water from water-rich areas to water-poor areas.
Can use damps, pumps, and lined canals aka aqueducts.
Has high environmental and social costs.Like the leaks in the water-transfer systems.
Desalinization:
is the process of removing dissolved salts from ocean water or from brackish water in aquifers or lakes. It is another way to increase supplies of freshwater.
widely methods used: distillation or reverse osmosis
