Water resources in namibia Flashcards
what is the difference between periodic and episodic rivers?
- Periodic only flows during rainy season when water table rises enough to feed the river.
Episodic flows for short periods after heavy rains.
- many in namibia.
- important source of water.
Why are lakes an important water resource in namibia.
- Valuable for many countries.
- Namibia does not have any real lakes.
What are pans?
- very common in namibia during or after good rain.
- are shallow basins of water that tend to evapourate easily.
- drying up leaves valuable fertile soil.
Importance of dams.
- Namibia large and small storage dams.
- supplying water for domestic and agricultural consumption.
- Omdel dam:
- build because seawater leaked into dam water, and the do was there to trap flood water and to allow all sediments to be deposited.
What is ground water?
- Refers to water that infiltrates surface of the earth and percolates underground where it is stored.
- plays an important part in dry countries.
Where is ground water found?
- found in aquifers.
- aquifers in gravels and sand is knows as alluvial aquifers.
- aquifers in harder rock, sandstone and limestone, are hard rock aquifers.
name the three process of desalination of seawater.
- Distillation
- Electro-dialysis
- reverse osmosis
Describe desalination in terms of distillation.
- seawater is boiled to cause evaporation and leaves salt behind.
- steam is condensed as fresh water.
- is fine for small quantities but not economically viable.
Why is permanent rivers permanent?
- The river channel reaches water table throughout the year.
Describe elevctro dialysis to de desalination.
- seawater placed in container with negative electrode at one end and positive electrode at the other.
- negative and positive charged ions move towards electrodes.
- salts become trapped between semi-permeable membranes in the container.
- water on one side of memebrane will be fresh and pumped out.
- left water will be salty and returned to sea.
Describe reverse osmosis in terms of desalination.
- Pressure is applied to seawater, forcing it through special memebranes.
- only water will pass through and salts will be caught in membrane.
Why do farmers irrigate?
- To supplement low rainfall in an area.
- to provide water throughout the year where rainfall is seasonal.
- to provide water in areas with high evaporation rate.
- to increase crop production.
What is the problems caused by irrigation?
- High cost of building and maintaining installations.
- reservoirs have limited life as they slowly fill up with river borne silt.
- may effect quality of the soil.
- great deal of water loss from reservoir through evaporation.
- can rise the water table.
- surface water evapourates, leaving salts behind: salination.
- when raining, salf may spread to other sources of water.
name the factors that contribute to pollution of water sources.
- Rapid urbanisation
- industrial activities.
- irrigation
- agriculture
- soil erosion.
why does urbanisation cause pollution?
- lack of toilets
- waste end up in water supply
- more people, more cars truck, diesel oil.
what is the consequences of pollution of the human and natural environment?
- environmental damages, ecosystems are disrupted.
- thougher plants, easily take over disrupted ecosystem.
- local communities start to suffer if water become polluted.
- people might loose income if all the fish die.
- poverty is the longterm effect.
how do we reduce water pollution in namibia?
- education:
Greater awareness of the problem. - increased awareness of causes and health hazards.
Legal system: - enforcing laws that combat the problem
- apoint inspectors to monitor the problem.
- laws can ban dumping of untreated sewage.
- increase tax on companies.
- more strict control.
- force companies that cause pollution to pay for and clean up action.
Improving water supplies in rural areas.
- will help to prevent water pollution.
Name the causes of water shortages.
- Draughts
- rapid population growth.
- overuse of water resources
- overstocking
- deferestation
- farmers plants thirsty crops.
- climate change in the form of global warming.
- growth of industries increases.
What is the effects of water shortages.
- Lack of clean water for momestic use.
- death of livestock
- desertification
- wind erosion
- conflict over water.
- poor quality of water.
