Definitions

Question 1

Subsurface Water

Answer 1

all water occurring beneath the Earth’s surface

Question 2

Groundwater

Answer 2

the subsurface water that occurs beneath the water table in soils and geological formations that are fully saturated

Question 3

Unsaturated Zone/Vadose Zone

Answer 3

the zone above the water table where pore water pressure is less than atmospheric (due to capillary forces)

Question 4

Capillary Fringe

Answer 4

saturated zone that sits above the water table in the vadose zone. Water is held in the capillary fringe due to surface tension forces, cohesion and adhesion.

Question 5

Saturated Zone/Phreatic Zone

Answer 5

The zone below the water table where water pressure is greater than atmospheric pressure and pores are saturated with water

Question 6

Interflow

Answer 6

Water that flow laterally through the unsaturated zone

Question 7

Aquifer

Answer 7

A GW reservoir composed of geological units that are saturated with water and are sufficiently permeable to yield water in a useable quantity to wells and/or springs

Question 8

Aquitard

Answer 8

A unit of low but not negligible permeability. Can be saturated or saturated to some degree

Question 9

Aquiclude

Answer 9

A unit of negligible permeability

Question 10

Piezometeric surface

Answer 10

The surface representing the level to which water would rise in boreholes puncturing the aquifer, where the groundwater pressure is equal to the atmospheric pressure

Question 11

Unconfined aquifer

Answer 11

An aquifer in which the water table forms the upper boundary. (water table = piezometeric level)

Question 12

Confined aquifer

Answer 12

An aquifer that is confined between two aquitards.

Question 13

How do you distinguish the potentiometeric surface and the piezometeric surface?

Answer 13

The potentiometeric surface is the level to which water will rise in any borehole. For unconfined aquifers, this is the water table. In unconfined aquifers, this is called the piezometeric surface

Question 14

Leaky aquifer

Answer 14

A leaky aquifer is a semi-confined aquifer. A water bearing formation with an underlying for overlying confining layer of low permeability that stored GW and also transmits it slowly from the aquifer

Question 15

Potentiometer surface

Answer 15

The potentiometer surface is a general term best used to mean either the water table (unconfined aquifers) or piezometeric surface (confined aquifer). It is the level to which water will rise in any borehole

Question 16

Artesian Aquifer

Answer 16

the water level in a well of a confined aquifer will rise above the level of the ground surface and flow freely without pumping.

Question 17

Perched aquifer

Answer 17

perched aquifers occur above discontinuous aquitards which allows GW to mound above them. Perched aquifers area in the unsaturated zone.

Question 18

Gaining stream

Answer 18

streams gain water from the inflow of groundwater through the streamed. the elevation of the water table is greater than or equal to the elevation of the water level in the stream,

Question 19

Losing stream

Answer 19

streams may lose water to the groundwater system by outflow through the stream bed. the elevation of the water table is less than the water level in the stream.

Question 20

Specific Yield

Answer 20

the volume of water that an unconfined aquifer released from storage per unit surface area of aquifer per unit decline of the water table

Question 21

Specific retention

Answer 21

the volume of water in an unconfined aquifer that is retained after drainage per unit surface area of aquifer per unit decline of the water table