Physical Factors Affecting Water Supply
- Created by: Amy Brown
- Created on: 04-06-14 17:37
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- Physical factors affecting water supply - Climate, River Systems and Geology
- Climate
- Regions near the equator receive high levels of annual precipitation
- Equatorial areas such as the Amazon have 2 distinct periods of wet weather per year
- Monsoon areas of Asia have 1 very wet season
- River Systems
- The worlds major rivers store large quantities of water and transfer it across continents
- Rive flow increases down stream as more tributaries flow into the river
- Geology
- Where rocks underlying a river basin are impermeable - water will remain on the surface creating a high drainage density
- Aquifers can store huge amounts of water underground
- Case Study: Factors affecting California's water supply
- Geographical Controls on water supply:
- Mountain chains run parallel to the coast and prevent moist air reaching inland
- Most rainfall falls in a coastal zone no more than 250km wide
- South and far east of California receive under 100mm of rainfall due to the rain shadow cast by the Sierra Nevada mountains
- High pressure systems over the Pacific ocean block moist air currents reaching southern California
- Most of the major rivers are fed by snow melt from the Sierra Nevada mountains
- In recent years extended through droughts have meant groundwater and surface storage levels gave decreased
- Threats
- Precipitation
- Much of California is arid with annual average precipitation of between 200-500mm
- 65% of precipitation is lost through evaporation, 13% flows out to sea = 22% for human use
- 50% of the rain falls between November and March = seasonal shortages
- Much of California is arid with annual average precipitation of between 200-500mm
- Population
- Grown from 2 million people in 1990 to 37.7 million in 2007
- Spatial imbalance as 3/4 of demand for water comes from areas south of Sacramento - 75% of rain falls to the north
- Increasing demands for water exceeds natural supplies
- Precipitation
- Geographical Controls on water supply:
- Climate
- 65% of precipitation is lost through evaporation, 13% flows out to sea = 22% for human use
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