Lecture 18

Question 1

Hydrologic cycle

Answer 1

Water moving through the environment.

Amount of water on Earth is relatively constant.

Question 2

Interception

Answer 2

Falling rain or snow can either fall directly to surface OR be intercepted/caught on plants before getting to surface, then can evaporate or drop to ground.

Question 3

Infiltration

Answer 3

Water seeps below surface.

Question 4

Runoff

Answer 4

Flows downhill over surface.

Question 5

Evaporation

Answer 5

Depends on relative humidity, wind, and temperature.

Question 6

Relative humidity

Answer 6

Dry air will have more evaporation (more room to soak up water), wetter air will will have less evaporation.

Question 7

Transpiration

Answer 7

Soil water taken up by plants and evaporated from surface of leaves.

Question 8

Porosity

Answer 8

Amount of open space between soil particles.

What infiltration depends on.

Question 9

Permeability

Answer 9

Ease with which water moves through soil.

Question 10

Infiltration factors

Answer 10

Vegetation; plants slow runoff, giving more time to infiltrate and roots loosen soil, increasing permeability and porosity.
Animals; can increase infiltration by loosening soil or lower it by compaction of the surface.

Question 11

Soil moisture

Answer 11

Water in soil; some attached to soil particles.

Question 12

Capillary water

Answer 12

Temporarily attached, available for plants to use.

Attraction decreases as more water attaches.

Question 13

Gravity water

Answer 13

Not attached water, gravity pulls it down.

Question 14

Field capacity

Answer 14

How much capillary water can a soil hold?

Question 15

Wilting point

Answer 15

Most capillary water gone, plants can’t get enough to stay healthy.

Question 16

Groundwater

Answer 16

Where all pore spaces filled with water - no air (zone of saturation).
Important natural resources.

Question 17

Renewable resource

Answer 17

Groundwater used and replaced by rainfall in humid environments.

Question 18

Non-renewable resource

Answer 18

Groundwater that may not get replaced in arid environments.

Question 19

Aquifer

Answer 19

Subsurface material that holds groundwater (porosity and permeability sufficient for water to accumulate).

Question 20

Aquiclude

Answer 20

Subsurface material with low permeability. Prevents groundwater from moving through it.

Question 21

Water table

Answer 21

Upper limit of groundwater.

Question 22

Artesian well

Answer 22

Water table higher than top of well, so water flows freely.

Depends on subsurface rock layers.

Question 23

Cone of depression

Answer 23

Using underground water often lowers the water table around the well, creating a cone/V shaped divot around the well.

Question 24

Subsidence

Answer 24

In some places, groundwater helps hold up the surface. Remove groundwater and surface will sink.

Question 25

Salt water intrusion

Answer 25

Along some coasts, removes fresh groundwater and salty water takes its place.

Question 26

Overland flow

Answer 26

Sheet flow; flows in uniform sheet over surface.
Rill; small concentrated flow.
Gully; moderate concentrated flow.
Stream; larger flow. Generic term for any concentrated flow.

Question 27

Throughflow

Answer 27

Water infiltrates soil but some moves parallel to slope and emerges downslope to become overland flow.

Question 28

Baseflow

Answer 28

Some groundwater, under the right circumstance, may feed water into a stream.
Only works if water table is higher than the bottom of stream.
Relatively constant. Keeps water flowing between rainstorms.

Question 29

Effluent stream

Answer 29

Water table higher than bed; stream is “perennial” if it is effluent/flows all year.

Question 30

Influent stream

Answer 30

Water table below bed; stream is “ephemeral” if influent all year/flows only with overland flow.

Question 31

Intermittent streams

Answer 31

Flows part of the year bc it is seasonally effluent.

Question 32

Hydrograph

Answer 32

Graph of streamflow overtime.