Water Supply

Question 0

River systems

Answer 0

World’s major rivers store large quantities of water and transfer it across continents.
The Amazon for example produces an average discharge of 219,000 m^3, this is 20% of the water entering the world’s oceans.
River flow generally increases downstream as tributaries feed into the main river.
Seasonal changes in climate can create variations in discharge.

Question 1

Climate

Answer 1

Distribution of water is related to climate zones.
Regions near the equator receive high levels of annual precipitation.
Rainfall can also vary with seasons.
High mountains with snowpack hold vast reserves of water.

Question 2

Geology

Answer 2

Where the rocks underlying a river are impermeable, water will remain on the surfaces run off, creating a high drainage density.
Aquifers can store vast quantities of water underground. For example the Ogallala Aquifer in the High Plains region of the U.S.

Question 3

Finite resource

Answer 3

A fundamental issue.
The world’s oceans hold about 1.386 million km^3 of water, about 97.5% of the world’s water - only 2.5% is fresh, almost 80% of that is trapped in ice, snow and permafrost. Only 1% is easily accessible.