Chapter 4

Question 1

What is groundwater?

Answer 1

The water found within the pore space of geological materials

• groundwater does not always follow land surface topography

Question 2

What is overland flow runoff generation?

Answer 2

caused by either infiltration excess or saturation excess

• when rate of precipitation is greater than infiltration capacity
• infiltration capacity is determined by soil porperties

Question 3

What is interflow runoff generation?

Answer 3

lateral movement of water in the unsaturated zone, entering streams without having occurred as overland flow

Question 4

What is groundwater runoff generation?

Answer 4

• in the saturated zone
• some groundwater flow paths respond to individual rainstorms, while others only respond to climatic changes over the years.

Question 5

What are gaining rivers and losing rivers?

Answer 5

• gaining rivers receive groundwater discharge from the watershed
• losing rivers recharge groundwater, since the groundwater table is below the river

Question 6

What is the vadose zone?

Answer 6

Also known as the unsaturated zone

Question 7

Where can we find groundwater?

Answer 7

in soils, rocks, and unconsolidated deposits

Question 8

What is the difference between macro and micro porosity?

Answer 8

• macropores grain freely by gravity and allow easy movement of air and water.
• micropores have diameters less than 0.08mm, and suction is required to remove water from micropores.

Question 9

What is the formula for porosity?

Answer 9

porosity = V voids / V total

Question 10

What is the formula for micro and macro porosity?

Answer 10

V pores = V micropores + V macropores

Question 11

What is permiability?

Answer 11

ability to move through a medium (soil/rock)

high porosity does not equal high permeability

clay has high porosity, but low permeability

Question 12

What are alluvial and aeolian deposits good for?

Answer 12

groundwater storage!

Question 13

What is recharge and discharge?

Answer 13

The two ways groundwater can move

• recharge = percolation: downward migration of water in vadose zone
• discharge is when groundwater emerges into springs, wetlands, rivers, lakes, oceans

Question 14

What is an aquifer?

Answer 14

• consists of layers or units of sands, gravels and rocks that contain sufficient saturated and permeable geologic material to yield a useable, sustainable amount of potable groundwater.

Question 15

What are the two classifications of aquifers?

Answer 15

• consolidated rock - sandstones, limestones, etc. Materials that do not allow groundwater to easily move through.
• unconsolidated rock - granular materials such as sand and gravel. Generally yields larger amounts of groundwater.

Question 16

What are aquitards and aquicludes?

Answer 16

Confining layers

• are geological formations that have low permeability and restrict the flow of water.
• can act as barriers that prevent the movement of water between aquifers or between groundwater and surface water.

Question 17

What is the hydraulic head?

Answer 17

The height of water in a column that can be supported by water pressure at a point of measurement.

Question 18

What is hydraulic gradient?

Answer 18

The difference in hydrological head over distance

Question 19

What is a piezometer (or pore measure meter)?

Answer 19

• pressure transducers that are installed beneath the ground to measure the sub-surface piezometric level within groundwater level, soil, or rock.
• they are used to study the effect of water in the pores of soil or rock is to reduce load bearing capacity of soil or rock.