Chapter 11 Groundwater

Describe several ways in which groundwater can become contaminated.

1. Pesticides and herbicides applied to agricultural crops can find their into groundwater. 2. Nitrate, formed from one of the most widely used fertilizers, is harmful in even small quantities in drinking water. 3. Rain can carry pollutants like toxic mercury and lead from city landfills into groundwater. 4. Liquid and solid wastes from septic tanks and sewage plants, as well as animal feedlots and slaughterhouses can contain bacteria, viruses, and parasites 5. Acid mine drainage form coal and metal mines can contaminate both surface and groundwater 6. Radioactive waste in shallow burial from the nuclear power industry 7. Also, naturally occurring minerals within rock and soil may contain elements such as arsenic, selenium, mercury, etc.

Factors of Poor Infiltration

1. heavy precipitation (only saturates surface) 2. steep slope (too much runoff) 3. Dense vegetation 4. Composition of subsurface materials (small poor space=poor infiltration)

An aquifer is

A body of saturated rock or sediment through which water can move easily

A sinkhole is...

A closed depression found on land surfaces underlain by limestone, They form by the collapse of a cave roof to by solution as descending water enlarges a crack in limestone.

A hot spring is...

A spring in which the water is warmer than human body temperature. Water can gain the heat underground by either groundwater circulating near a magma chamber or a body of cooling igneous rock.

Name several geologic materials that make good aquifers. Define aquifer.

An aquifer is a body of saturated rock or sediment through which water can move easily. Aquifers are both highly permeable and saturated with water. Good aquifers include sandstone, conglomerate, well-jointed limestone, bodies of sand and gravel, and some fragmental or fractured volcanic rocks such as columnar basalt.

How does a confined aquifer differ from an unconfined aquifer?

An unconfined aquifer has a water table because it is only partly filled with water, and a confined aquifer is completely filled with water under pressure and is usually separated from the surface by a relatively impermeable confining bed. A confined aquifer is better for drinking water and agriculture because of its unpolluted water due to the impermeable barrier and slow recharge.

Groundwater

Groundwater is an essentially non renewable, slow recharge, natural resource that is 35x the amt of all the water in streams + lakes combined.

What controls the velocity of of groundwater flow?

Permeability, the pressure of water within the saturated zone, and the elevation of water win the saturated zone.

Discuss the difference between porosity and permeability.

Porosity refers to the amount of open pore space in a given volume of rock or sediment. Permeability refers to the ability of a material to transmit a fluid through it.

Gaining Streams

Receives water form the saturated zone ie. springs, lakes, streams, surface of stream coincides with water table.

The subsurface zone in which all rock openings are filled with water is called the

Saturated zone

Losing Streams

Streams where the water eventually drains down to the water table at depth

Permeability is

The capacity of a rock to transmit a fluid.

Hydrolic Cycle

The circulation of water through the Earth-Atmosphere System... Atmospheric water from water vapor gas, clouds, and ice crystals precipitates onto the Earth's surface creating lakes streams, glaciers, vegetation,etc, and then infiltrates the interior, creating groundwater.

What is the water table? Is it fixed in position?

The water table marks the surface of the saturated zone and the separation of the saturated sone, in which all the rock openings are filled with water, to the unsaturated zone, or the zone where not all the sediment or rock openings are filled with water. It is not fixed position because....

What happens to the water table near a pumped well?

When water is pumped form a well, the water table is typically drawn down around the well into a depression shaped like an inverted cone known as a cone of depression. In turn, this lowers the water table around the region of the well.

The drop in the water table around a pumped well is the a. drawdown b. hydraulic head c. porosity d. fluid potential

a. drawdown

Porosity is a. the percentage of a rock's volume that is openings c. the ability of of a sediment to retard water

a. the percentage of a rock's volume that is openings

Groundwater flows a. always downhill b. from areas of high hydraulic head to low hydraulic head c. from high elevation to low elevation d. from high permeability to low permeability

b. from areas of high hydraulic head to low hydraulic head

Which rock type would make the best aquifer? a. shale b. mudstone c. sandstone d. all of the preceding

c. sandstone

Which of the following determines how quickly groundwater flows? a. elevation b. water pressure c. permeability d. all of the preceding

d. all of the preceding

Recharge refers to..

the addition of new water to the saturated zone

Subsidence is..

the gradual caving in or sinking of land, in this case, referring to the subsidence of land surface caused by the extraction of groundwater, which causes compaction and the reduction of pore space.