Groundwater resources

Question 1

What are the properties of the hydrologic cycle?

Answer 1

-Precipitation
- Infiltration
- Runoff
- Water balance
- evaporation
- transpiration
-sublimation

Question 2

Precipitation

Answer 2

Anything that is falling, rain or snowfall on the land or ocean

Question 3

infiltration

Answer 3

Water that is soaked into the ground
- Fills cracks and pore spaces in soil or rocks

Question 4

Runoff

Answer 4

The portion of precipitation that does not infiltrate into the ground but flows over the surface and eventually collects in streams, lakes, oceans

Question 5

Water balance

Answer 5

Flow in = Flow out

Question 6

Evaporation

Answer 6

Transformation of a fluid form to a gas form.
- water from open bodies of water becomes vapour in the atmosphere

Question 7

transpiration

Answer 7

Groundwater is absorbed into plant roots, carried up to the leaves, and re-enters the atmosphere as water vapour.

Question 8

Sublimation

Answer 8

Snow or ice transforms directly from solid form to gas form and returns to the atmosphere.

Question 9

Water table

Answer 9

-Boundary underground that separates saturated and unsaturated layers

-Upper surface of the zone of saturation, which is the area beneath the Earth’s surface where the soil and rock are completely saturated with water.

Question 10

Where is water stored underground?

Answer 10

-Pore spaces and fractures of sediments and rocks

-mostly in gravel and sand (high porosity and permeability)

• can be in clay and silt as well (high porosity, low permeability)

Question 11

Porosity

Answer 11

volume of pores/ voids in rock/ soil
- how much void space is present per unit volume of rock sediment

Question 12

Permeability (k)

Answer 12

-permeable means that voids are connected, allowing fluid to pass through

• reflects how pore space in a porous medium are connected

Question 13

Hydraulic conductivity (K)

Answer 13

-capacity of a material to transmit fluids
-K = k(pg)/u
p= density of fluid
k= permeability of the medium
g = gravitational acceleration
u = viscosity of the fluid

Question 14

hydraulic head (h)

Answer 14

-represents the potential energy of groundwater at a specific point in an aquifer or water system

hydraulic head = pressure head + elevation head

elevation head
-Represents the height of the point above a chosen reference point (usually sea level is set at 0)

pressure head
-From the top of the elevation head to the water table

Question 15

hydraulic gradient

Answer 15

Water flows from a higher hydraulic head to a lower hydraulic head
-follows the topographic pattern
i = (h1-h2)/L

Question 16

Darcy’s Law (Flux)

Answer 16

Understand how much water will flow in and out
q = K i
K = hydraulic conductivity
i = hydraulic gradient

Question 17

recharge areas

Answer 17

-areas where precipitation and infiltration occur

-adds water to the ground
-when hydraulic head is highest

Question 18

discharge areas

Answer 18

• areas where water seeps out of the ground as springs or enters rivers, lakes, or oceans

-decrease in groundwater
- hydraulic head is lowest

Question 19

What is an aquifer, and what are the 2 types of aquifer

Answer 19

• can transmit significant quantities of water which wells can tap for water supply

Confined aquifers
- between two impermeable or relatively impermeable layers of rock it sediment
- between 2 aquitards
-blocks vertical movement of water

Unconfined aquifer
-the upper surface of the groundwater (water table) is not confined by impermeable layers
- water is free to rise and fall

Question 20

Cone of depression

Answer 20

-pumping water from an unconfined aquifer
-drops water table
- can recover by stopping the pumping of water
- recovery speed depends on the permeability and porosity of the aquifer