Env Science#3 Waster Use

What is the hydrologic cycle?

The natural process by which water is purified and made fresh through evaporation and precipitation.

Define rain shadow.

A dry area on the downwind side of a mountain.

What does residence time refer to?

The length of time a component, such as an individual water molecule, spends in a specific compartment or location before it moves on.

What is groundwater?

Water held in gravel deposits or porous rock below the earth's surface.

What is infiltration?

The process of water percolation into the soil and the pores and hollows of permeable rocks.

What is the zone of aeration?

Upper soil layers that hold both air and water.

What defines the zone of saturation?

Lower soil layers where all spaces are filled with water.

What is the water table?

The top layer of the zone of saturation; undulates according to the surface topography and subsurface structure.

What are aquifers?

Porous, water-bearing layers of sand, gravel, and rock below the earth's surface; reservoirs for groundwater.

What is an artesian well?

A pressurized aquifer from which water gushes without being pumped, due to the aquifer intersecting the surface or being penetrated by a pipe.

Define recharge zones.

An area where water infiltrates an aquifer.

What is discharge?

The amount of water that passes a fixed point in a given amount of time.

What are renewable water supplies?

Annual freshwater surface runoff plus annual infiltration into underground freshwater aquifers that are accessible for human use.

What is water scarcity?

When annual available freshwater supplies are less than 1000m^3 (264,000) per person.

Define water stress.

A situation when residents of a country don't have enough accessible, high-quality water to meet their everyday needs.

What does withdrawal refer to in water terms?

The total amount of water taken from a lake, river, or aquifer.

What is consumption regarding water?

The fraction of withdrawn water that is lost in transmission or otherwise made unavailable for other purposes.

Define saltwater intrusion.

Movement of saltwater into freshwater aquifers in coastal areas where groundwater is withdrawn faster than it is replenished.

What is subsidence?

A settling of the ground surface caused by the collapse of porous formations from the withdrawal of large amounts of groundwater, oil, or other underground materials.