Geol 101 Ground Waters And Rivers

Front 1

Runoff

Back 1

draining away of water (or substances carried in it) from the surface of an area of land

Front 2

Infiltration

Back 2

process by which water on the ground surface enters the soil

Front 3

Infiltration Properties

Back 3

Porosity , Permeability

Front 4

Porosity

Back 4

Measure of the void (empty) spaces in a material

3 types:
Inter-granular pores
Fractures
Vugs

Front 5

Intergranular pores

Back 5

Porosity between grains

Front 6

Fractures

Back 6

Porosity caused by fractures: very low aspect ratio therefore easily compressed

Front 7

Vugs

Back 7

Small to medium sized cavities inside rock. Usually filled with crystals (quartz). Can resist compression very effectively due to its shape

Front 8

Controls on Porosity

Back 8

Gravel: well sorted high porosity
Clay: High Porosity
Gravel, Sand, Clay: poorly sorted, low porosity
Cemented sandstone: Low porosity

Front 9

Permeability

Back 9

Ease with which fluid is transmitted through a rocks pore space. measure of how interconnected the individual pore spaces are in a rock/sediment

Front 10

Water Table

Back 10

Point/line below the ground where all the pores become water filled. zone of saturation just below it and zone of aeration above it.

Front 11

Aquifer

Back 11

underground layer of water-bearing permeable rock or gravel,sand,silt from which groundwater can be extracted. (wells)

Front 12

Unconfined

Back 12

water seeps directly to into the aquifer

Front 13

confined

Back 13

there is a impermeable rock layer that prevents water to seep directly into the aquifer from above. Better because it wont contaminate easily

Front 14

Artesian well

Back 14

well in which pressurized water naturally rises to the surface

Front 15

Perched aquifer

Back 15

a type of unconfined aquifer that sits above an unconfined aquifer because water infiltrating from the surface is trapped or perched by an impervious layer

Front 16

Recharge

Back 16

process by which ground water is replenished. Area in which water is transmitted to an aquifer,

Front 17

Discharge

Back 17

locations at which ground water leaves an aquifer and flows to the surface. occurs where water table intersects the land surface
increases untill channel cannot contain all water, then flooding occurs:
Discharge = Velocity x Area

Front 18

Overdrafting

Back 18

When you have more Discharge than Recharge

Front 19

Cone of Depression

Back 19

is a valley/cone that is created by a well when it pulls groundwater to the surface.

Front 20

Subsidence

Back 20

occurs when large amounts of groundwater have been excessively withdrawn from an aquifer.

Removal of water creates an empty void/space where sediment will settle downward and fill. It is difficult to recharge an aquifer b/c pores are now full of sediment

Front 21

Effects of Overdrafting

Back 21

Salinity Contamination
Problem along coastlines
Salt water infiltrated depleted aquifers
rising sea level contributes
Desalinization

Front 22

Desalinization

Back 22

To remove salts and other chemicals from seawater or soils

Front 23

GroundWater Movement

Back 23

Tends to move very slow
Erodes even at slow speeds
carries dissolved substances: CO2, dissolved carbonate rocks

Front 24

Case Study: Groundwater Contamination

Back 24

Love Canal, Niagra Falls NY
abandoned canal turned into a chemical waste dump, 1940
Property there was under construction, which broke containment seals. Chemicals reached water table by 1970's.
Increased cases of illness - asmtha, infection, cancer
birth defect rate 56% by mid 70's
21,000 tons of chemical waste underground
1980 superfund Act, companies pay for clean up

Front 25

Rivers and Streams

Back 25

Major agent of weathering and erosion
irrigation, drinking water, flooding

developed areas experience more runoff, less infiltration

Front 26

Drainage Basin

Back 26

Area that contains all water flowing down into a river Channel

Front 27

River

Back 27

V-Shaped valley
Channel
runoff abrades underlying soil/rock

Front 28

Tributaries

Back 28

stream of river that flows into a main stem either a larger river or lake.

Front 29

Tributari patterns:

Back 29

Branching/dendritic (random branching)
Radial (circular)
Trellis (rectangular branching)

Front 30

Levee

Back 30

like an embankment beside a river

Front 31

Floodplain

Back 31

flat areas along streams/rivers that are likely to experience repeated flooding.

Front 32

Channels

Back 32

Some rivers have multiple channels - braided streams
causes: Variable discharge, heavy sediment supply, easily erodible banks

Front 33

Meandering

Back 33

Channels that flow in a winding course. S shaped rivers
water on the outside of a meander must move faster to keep up with the water on the inside of the bend/turn

Front 34

Cut Bank

Back 34

Area of erosion, outside of a meander

Front 35

Point Bar

Back 35

area of deposition, formed by deposited minerals inside the stream bend/turn

Front 36

Oxbows

Back 36

U shaped bend in a river or stream, whether or not it is cut off from the main stream

Front 37

Meandering effects

Back 37

it can be artificially straightened but causes problems:
habitat loss
more severe flooding
Crabtree valley mall

Front 38

Floodplain development

Back 38

Floods deposit lots of fine-grained sediment

Front 39

Recurrence intervel

Back 39

time between two floods of the same size
Probability in a given year: 1 / (yearly interval occurrence)

5 year flood has a 20% of occurring once a year

Front 40

Mouth

Back 40

part of a river where a river flows into the sea,lake,ocean

Front 41

Distributaries

Back 41

stream that branches off and flows away from a main stream channel

Front 42

Deltas

Back 42

Landform that is formed at the mouth of a river where the river flows into an ocean

Front 43

Lobes

Back 43

accumulation of sand and silt deposits that were carried by the river and deposited in the delta.

Front 44

Potable

Back 44

Drinkable water

Front 45

Fecal Coliform Count

Back 45

(# of coliform bacteria) / 100ml
Drinking water = 0
swimming/etc = 200

Front 46

Chemical Contamination

Back 46

Chemicals commonly added to water via infiltration and runoff: pesticides, fertilizers
so can radiation: mines, waste disposal

Front 47

Water quality clean up

Back 47

Clean up is possible but difficult, takes time & money
Faster recharge = easier to clean once contaminant source is isolated
Recover = matters of years

Front 48

Water Availability

Back 48

Legal fights amont states over who gets x amount of water. Downriver states suing upriver states for taking too much

Front 49

SC vs NC case study

Back 49

Catawba River accounts for half the water supply to SC low country

10million gallons fron catawba river annually

Front 50

GA vs TN Case study

Back 50

Georgia legislature proposed state border be moved 1mile north. Claim based on surveying error placing border in wrong location.

Front 51

Colorado river overuse

Back 51

Providing water to 30million people
70% of its water diverted to irrigate 3.5million acres
Decade of drought
water level down 130ft since 2000
Delta reduced from 3000 acres to 250 acres in last century