Feb 27 2010
Water Shortages
Rain is a good thing
As a review, we went over the water cycle and the unique properties of water. These are important for this unit so be sure you understand those. If you need any clarification here’s a good website that might spark your memory: http://techalive.mtu.edu/meec/module06/title.htm
Picture of the water cycle http://cd7.e2bn.net/e2bn/leas/c99/schools/cd7/website/images/bp-watercycle2.jpg
Here is some easily mixed up terminology:
Groundwater: when precipitation infiltrates the ground and percolates downward through spaces in soil, gravel, and rock. IE GROUND WATER IS UNDERGROUND.
Aquifers:
This is NOT a good diagram of an aquifer because aquifers are NOT underground rivers. The water is stored between sand, gravel, or bedrock. The water moves SLOWLY
Humans use about 50% of world’s reliable run off (water we can control)!
There are 4 CAUSES of water shortages
- Dry Climate– Western united states is mostly desert, therefore there is little rainfall which can cause extensive water shortages.
- Drought– Drought is caused by low levels of percipitation ( at a 30 year low)
- Dessication– this is what caused the dust bowl. This is when there are no plants to hold down soil and it become depleated
- Water stress– This is the demand for water.
HOW CAN WE FIX GROUNDWATER DEPLETION?
we can prevent it by: wasting less water, subsidizing water conservation, limiting the number of wells, and not growing water-intensive crops in dry areas
we can control it by: raising price of water, tax water pumped from wells near surface areas, set and enforce minimum stream flow levels
There are 4 SOLUTIONS for water shortages
1. DAMS–store water up. resevoir
There are advantages and disadvantages of this:
ADVANTAGES: provides irrigation water above and below dam, provides drinking water, useful for recreation and fishing, produce cheap electricity
DISADVANTAGES: flooded land destroys forests of cropland, large losses of water through evaporation, deprives downstream cropland and estuaries of nutrient-rich soil
2. Transfer water– where a lot of water is to where it is needed.
This is useful, but may lead to the ARAL SEA DISASTER! [ see case study on page 237-238]
3. Desalinization– people who live in coastal area
desalinization involves removing dissolved salts from ocean water or from brackish water in aquifers of lakes to increase supplies of freshwater.
There are 3 main problems with it: 1) HIGH COST; 2) KILLS MANY MARINE ORGANISMS; 3) PRODUCES BRINY WATER THAT CONTAINS A LOT OF MINERALS
4. Conserve water-- using less water.
WE NEED TO USE WATER SUSTAINABLY:
- waste less water and subsidize water conservation
- do not deplete aquifers
- preserve water quality
- protect forests, wetlands, mountain glaciers, watershed and other natural systems that store and release water
- get agreements amoung regions and countries sharing surface water resources
- raise water prices
- slow population growth
“THE FROG DOES NOT DRINK UP THE POND IN WHICH IT LIVES!!”
