Lecture 9

Of all the water in the world, freshwater constitutes

• 1%

• 2.5%

• 30.1%

• 68.6%

Of the freshwater on Earth's surface, water in rivers makes up

• 0.22%

• 0.46%

• 20.1%

• 73.1%

The constant circulation of water in the hydrosphere, the atmosphere, the geosphere, and the biosphere is called the

• Earth resource cycle

• the perpetual cycle

• the hydrologic cycle

• the natural cycle

The process by which plant release water into the atmosphere is called

• perspiration

• respiration

• exhalation

• transpiration

Collective term for water lost by plants through transpiration and water that evaporates into the atmosphere is

• inhalation

• secretion

• evapotranspiration

• exudation

the source area of a stream is also called the

• mouth

• the delta

• the reach

• the head or headwaters

When water flows in a steam in straight lines that are parallel to the channel it is called

• lamina flow

• turbulent flow

• rill flow

• meandering

Bends or loops that develop in stream channels are called

• braids

• meanders

• gravel bars

• channel lag

Steams erode their channels by

• abrasion

• plucking

• dissolution

• all of the above

Rounded depressions on riverbeds are called

• craters

• bowls

• caverns

• potholes