Based on your prior knowledge, create and LABEL a sketch of the hydrologic cycle.

aka … Water Cycle

21 Oct 2025

FRESHWATER

The Water Cycle

There is a continuous movement of WATER from the atmosphere to the earth’s SURFACES and then back to the ATMOSPHERE.

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This cycle of water movement is called the WATER CYCLE or the HYDROLOGIC CYCLE.

EVAPOTRANSPIRATION: evaporation and transpiration = organisms giving off water vapor

RUNOFF: water flowing into rivers

INFILTRATION: water soaking into the ground

CONDENSATION: water vapor turning into liquid water

PRECIPITATION: water falling to Earth- snow, rain, etc.

WATER BUDGET:

The continuous CYCLE of evapotranspiration, condensation and precipitation gives the earth its WATER BUDGET.

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Expenses: EVAPOTRANSPIRATION, RUNOFF

Income: PRECIPITATION, CONDENSATION

Factors affecting the local water budget:

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• TEMPERATURE
• VEGETATION
• WIND
• AMOUNT OF RAIN
• DURATION OF RAINY SEASON

**Earth’s water budget as a whole is balanced, but the local water budget usually is not balanced **

WATER CONSERVATION:

Scientists have identified 2 approaches that can be used to ensure there is FRESHWATER for the future.

CONSERVATION: antipollution laws; education on water conservation

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Finding other supplies of water:

DESALINATION: process of removing salt from ocean water.

Explain the process that forms an oxbow lake.

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You can either use labeled diagrams OR a sequence of

sentences.

24 Oct 2025

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1. Meander forms in river
2. Meander gets tighter (closer together)
3. Flood event causes water to flow over the meander (at the neck)
4. Water cuts a new channel across the neck of the meander
5. Water begins to flow through new pathway
6. Sediment build-up closes off meander
7. Oxbow lake is formed

Groundwater & Erosion

Water Beneath the Surface

Water that seeps into the upper layers of the earth’s crust is called GROUNDWATER.

90 % of earth’s freshwater is underground.

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In the US, groundwater supplies 20 % of the freshwater needs.

Amount of groundwater is 50 times greater than that of rivers and streams.

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AQUIFER: a body of rock through which large amounts of water can flow and in which much water is stored.

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The quality of the aquifer depends on:

(2 THINGS)

1. POROSITY - the amount of water that a rock can hold, refers to the amount of open space present

• The main influence of porosity is SORTING
• Well sorted soil – particles are all the SAME size
• Poorly sorted soil – particles are all DIFFERENT sizes

POORLY SORTED

MEDIUM SORTED

WELL SORTED

The quality of an aquifer depends on:

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2. PERMEABILITY - indicates how freely water passes through the open spaces, the spaces must be CONNECTED.

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If water cannot flow through the rock, it is said to be IMPERMEABLE. (aka AQUITARD)

GRAVITY pulls water down through the rock until it reaches an impermeable layer. Water then begins to SATURATE the pore spaces above the impermeable rock.

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ZONE OF AERATION - area above the impermeable layer where the pore spaces are filled with air.

ZONE OF SATURATION - area directly above the impermeable layer where the pore spaces are filled with water.

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WATER TABLE - the upper part of the zone of saturation

Groundwater can be polluted by:  

• WASTE DUMPS
• LEAKING UNDERGROUND STORAGE TANKS
• FERTILIZERS & PESTICIDES
• SALTWATER

INTRUSION

Groundwater can be conserved by:

• MONITOR LEVEL OF GROUNDWATER
• RECYCLE USED WATER
• PURIFY
• PUMP BACK INTO THE GROUND

Two ways that groundwater comes to the surface are:

WELL - a hole that is dug below the water table and then pumped to the surface

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SPRING - a natural flow of groundwater found where the ground dips below the water table

Wells & Springs:

Two main types of wells and springs:

1. ORDINARY - as described above

2. ARTESIAN - one through which water flows freely with no pumping required.

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This requires that the water is trapped between two IMPERMEABLE layers. The impermeable layer on top is known as the CAP ROCK. Once the cap rock is penetrated, the water trapped below flows freely to the surface.

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The area of the water table around a well often dips down and is known as a CONE OF DEPRESSION.

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1. What is the main difference between point source and non-point source pollution?

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2. Give ONE example of each:

P.S. –

N.P.S. –

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3. Which one is easier to identify & cleanup?

WHY??

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Point source

Because you only have one area to clean and not try to get EVERYONE to participate

27 Oct 2025

Point source – you can POINT to the source

Non-point source – can’t identify just ONE source

a chemical company spills into a river

everyone trying to have the best yard & fertilizers wash into local stream

HOT SPRINGS - groundwater that is heated below ground and then flows to the surface. It is often heated by recent VOLCANIC activity or is near pockets of MAGMA.

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Hot springs that erupt periodically are known as GEYSERS. (Ex. OLD FAITHFUL in Yellowstone National Park)

Groundwater and Chemical Weathering:

As water passes through rock, it DISSOLVES minerals. The WARMER the rock and water are, the more minerals that will dissolve.

HARD WATER:

• Contains minerals (such as calcium, magnesium, iron)
• Can damage household appliances

Results of Chemical Weathering by Groundwater:

CAVERN - a large underground chamber, hollowed out by the action of water

SINKHOLE - circular depression caused when the roof of a cavern collapses

22 Oct 2025

1. HOW does the water actually get into the river?

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2. What factors determine how much

water gets into the river?

Runoff from the land makes its way to the small streams that later connect to the river (tributary)

• amount of runoff - determined by amount of impermeable vs permeable surfaces
• amount of precipitation

River Systems

A river system is made up of a MAIN STREAM and all the feeder streams, called TRIBUTARIES, that flow into it.

WATERSHED: land from which water runs into stream (aka drainage basin)

DIVIDES: elevated areas of high ground. Separate watersheds

A river system begins to form when local PRECIPITATION exceeds EVAPORATION. The SOIL soaks up as much water as it can. GRAVITY causes excess water to move DOWNSLOPE as RUNOFF.

STREAM EROSION:

The path that a stream follows is a CHANNEL.

HEADWATER EROSION: lengthening and branching of a stream

STREAM PIRACY: “capture” of one stream by another

CHANNEL EROSION:

The edges of a stream that are above water are called BANKS. The part of the stream channel that is below the water level is the BED. A stream gradually becomes WIDER and DEEPER as it erodes.

Stream Loads:

Materials that are carried by a stream are known as the STREAM LOAD.

DISCHARGE GRADIENT:

A stream’s ability to cut down and widen channel is affected by VELOCITY, STREAM LOAD, and DISCHARGE.

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A FAST moving stream carries more SEDIMENT than a slow moving stream.

DISCHARGE: volume of water moved by a stream

GRADIENT: steepness of slope

HEADWATERS: beginning of a stream

STAGES OF A RIVER SYSTEM:

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The development of a river is divided into 3 stages - YOUTHFUL, MATURE, and OLD.

YOUTHFUL RIVERS:

• Few tributaries
• Small volume of water
• Not much meandering

MATURE RIVERS:

• More tributaries
• More water (larger volume)
• Some meanders

Meanders – curving of rivers

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Oxbow lake – a lake is formed from a meander

OLD RIVERS:

• Many tributaries
• Broad, flat plains
• Lots of meanders

REJUVENATED RIVERS:

A river that gains steep gradient by some shift in the land

Stream Deposition

The total load a stream can carry is GREATEST when a large VOLUME of water is flowing. When the VELOCITY decreases, the ability of the stream to carry its load also DECREASES. As a result, part of the stream load is DEPOSITED.

DELTA AND ALLUVIAL FANS:

Most of the LOAD carried by a stream is DEPOSITED when the stream reaches a LARGE BODY OF WATER.

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DELTA: fan-shaped deposit at mouth of river

ALLUVIAL FAN: fan-shaped deposit at bottom of slope on land

DELTA

ALLUVIAL FAN

DIFFERENCES

FLOOD DEPOSITS:

The SIZE of a stream channel is determined by the average VOLUME of water that flows in the STREAM. The part of the VALLEY FLOOR that may be covered with water during a FLOOD is called the FLOODPLAIN.

SPRING FLOODS: water released by melting snow

ICE JAMS: ice blocking stream channels

NATURAL LEVEES: deposits along banks of streams

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Why do people choose to live on floodplains?

FERTILE SOIL and LOTS OF WATER FOR USE

FLOOD CONTROL:

ARTIFICIAL LEVEES

OVERFLOW CHANNELS

FLOOD CONTROL DAMS

1. Define a wetland.

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2. What are some other names for wetlands?

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3. What would you expect to see in our Green Hope wetland?

23 Oct 2025

frogs & tadpoles, snakes, lizards, birds, deer, raccoons, foxes, fish

An area that is covered with water for all or part of the year.

swamps, marshes, bogs, billabongs

Create a labeled diagram of an aquifer with the following features:

28 Oct 2025

• zone of saturation
• zone of aeration
• impermeable layer
• water table
• recharge area
• ordinary well that shows the cone of depression

OCEANS

Water is the basic substance into which SOLIDS and GASES are dissolved. This solution is called OCEAN WATER or SEA WATER. Besides dissolved substances, small particles of MATTER and tiny ORGANISMS may also be suspended in ocean water.

Properties of Ocean Water

CHEMICAL PROPERTIES - enables dissolving of substances

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PHYSICAL PROPERTIES - temperature, density and color

1. SALTS - water evaporating and leaving solids (salts) behind

2. GASES - enter directly from the atmosphere

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Elements: 96.5% H2O, 2% NaCl, 1.5% EVERYTHING ELSE

3 Dissolved Gases: N2, O2, CO2 (dissolves most easily)

COMPOSITION OF OCEAN WATER:

• The amount of SALT present in ocean water is known as SALINITY.
• This is increased by both EVAPORATION and FREEZING.
• Most of the oceans have salinity ranging from 3.3% to 3.6%. However it can vary greatly. (ex. Red Sea = 4.0%).

Salinity of Ocean Water:

Temperature of Ocean Water

The SUN directly heats the SURFACE of the ocean. In deep zones, the temperature of the water is usually about 2^OC (just above the -2 degree freezing point).

SURFACE TEMPERATURE:

• Movement of ocean water mixes the warm surface waters
• More solar energy falls at the equator than the poles
• Ocean water freezes at -2 ^o C

THE THERMOCLINE:

• Zone of rapid temperature change
• Warm and cold water do not mix
• Below the thermocline, the temperature of water still falls – but VERY slowly.

Density = MASS PER UNIT VOLUME

(D = m/V)

Ocean water becomes MORE dense as it becomes colder and LESS dense as it becomes warmer.

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The most dense water is found at the POLES. Water is most dense at 4^o C.

Density of Ocean Water:

The color of ocean water is determined by the way it absorbs or reflects SUNLIGHT.

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Only the BLUE wavelengths tend to be reflected.

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No light of any kind can pass through ocean water at depths below 200 m. Only the upper regions show color. The rest is in total darkness.

Color of Ocean Water:

Sketch a river from its headwaters to the mouth where it empties into the ocean.

Label the following:

headwaters

tributary

meander

oxbow lake

ocean

delta

29 Oct 2025

Headwaters

Meander

Oxbow Lake

Mouth

Delta

Tributary

THE MOTION OF THE OCEAN

The waters of the ocean move in giant streams called CURRENTS. Oceanographers know that there are two major types of currents:

1. SURFACE CURRENTS - move on or near the surface
2. DEEP CURRENTS - move much more slowly deep beneath the surface.

Ocean Currents

Surface Currents

Ocean water can be set into MOTION only if it receives ENERGY.

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The driving force behind ocean currents is the WIND.

3 Factors Affecting Ocean Surface Currents:

1. WIND BELTS - push currents in the same direction of the wind movement
2. EARTH ROTATION- ocean moves with the earth’s rotation
3. CONTINENTS - act as barriers to currents

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The CORIOLIS EFFECT is also is a major factor controlling surface currents. This is the deflection of the winds and ocean currents caused by Earth’s rotation. This causes huge circles of moving water to form.

WARM EQUATORIAL CURRENTS - two warm currents that are found in the three main oceans and move WESTWARD.

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Between them is a weaker EASTWARD flowing current called the equatorial countercurrent.

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GULF STREAM - a swift warm current that pushes water through the Caribbean Sea & Gulf of Mexico and moves up the east coast of the United States.

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NORTH ATLANTIC DRIFT- very slow moving warm current forms as the Gulf Stream ends.

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Currents in the northern hemisphere move in a CLOCKWISE direction, while currents in the southern hemisphere move in a COUNTERCLOCKWISE direction.

Deep Currents

In addition to WIND-DRIVEN surface currents, the ocean has COLD, DENSE currents that flow very slowly, deep beneath its surface.

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The movements of these polar waters is a result of differences in DENSITY.

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The higher DENSITY of polar waters is also a result of an increase in the SALINITY OF THE WATER.

Intertidal Zone

The daily changes in the level of the ocean surface are known as TIDES. According to Isaac NEWTON, the gravitational pull of the MOON on Earth is the main cause of tides.

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LOW TIDE - form halfway between high tides, ocean water flows away from the shore

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HIGH TIDE - water moves towards the shoreline, due to the pull of the moon

Tides

Behavior of Tides

If the earth did not move, then tides would always occur In the same place.

TIDAL RANGE - difference between the level of high and low tides.

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SPRING TIDE -

occur during a new and full moon (twice a month) largest tidal range

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NEAP TIDE -

also occur twice a month during 1^st and 3^rd quarter moons smallest tidal range

Tidal Variations

Tidal patterns are greatly influenced by SIZE, SHAPE, DEPTH, and LOCATION of the ocean basin.

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DIURNAL Tidal Patterns: 1 high and 1 low tide per day (ex. Gulf of Mexico)

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SEMI-DIURNAL Tidal Patterns: 2 high and 2 low tides per day (ex. Atlantic Ocean)

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The greatest differences in tidal oscillations (change between high and low tide) create the largest TIDAL RANGE and are found in the narrow V-shaped Bay of Fundy, located in NOVA SCOTIA.

LET’S GO SWIMMING!!!

TIDES Activity

1. Make a sketch that shows a young river AND an old river. List the differences.

2. Create a sketch that shows: zone of saturation, zone of aeration, water table, a well with a cone of depression.

Zone of saturation

Water table

Zone of aeration

30 Oct 2025

EROSION BY

WIND & WAVES

Wind Erosion

Wind has energy. That energy can be used to push a sailboat, turn turbines, and erode the land.

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Wind can erode DRY land better than WET land because the water in wet land holds the SOIL PARTICLES together.

As the wind erodes, it carries rock particles along. There are two types:

Wave Erosion

Shoreline Erosion – The land bordering an ocean can be eroded in two main ways:

1. ABRASION- the striking force of the waves can break off pieces of rock and carry them back to the shore.
2. CHEMICAL WEATHERING - salt and air get into the cracks and will chemically break

Some of the features formed as a result of these processes include:

sea cliffs, sea caves, arches, stacks

BEACH - a deposit of sand or larger rock fragments along an ocean shore or a lakefront

The composition depends on two factors:

1. SOURCE ROCK - the type rock in the surrounding area

• GRANITE = light colored fragments (common in N. America)
• VOLCANIC ROCK = dark colored (black sand beaches in Hawaii)

2. ACTION THAT DEPOSITED THE MATERIAL THERE:

• Rivers and streams may carry the source rock to shore.
• Some beaches are made of shells and coral that washed ashore.
• Glaciers may have deposited it.

Coastal Erosion and Deposition

While coastal features vary, most are formed by a change in SEA LEVEL relative to the LAND.

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Sea level greatly affects the appearance of the coastline.

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SEA LEVEL - the average of high and low tides measured over many years

Sea level is currently rising at a rate of 2-4cm per year (IPCC report of 2021 predicts 8-30 cm rise by 2030). This change is mainly because of the MELTING OF GLACIERS and THERMAL EXPANSION OF WATER.

Why should we care?

What’s causing this rise in sea level?

Water also expands on a molecular basis as it gets warmer → sea level rise.

Submergent Coastlines:

Land can rise or sink because it is floating on the asthenosphere. Highest parts of submerged land can form islands. These features are re-shaped over time due to erosion.

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ESTUARY - when the mouth of a river gets submerged by ocean water, forming a wide shallow bay.

Characteristics include:

• SLIGHTLY SALTY
• IMPORTANT SOURCE OF CRABS & SHRIMP
• BREEDING GROUNDS FOR MANY SPECIES

BRACKISH WATER - salty and freshwater mixed

SALINITY - refers to the amount of salt content in the water

(higher salinity = higher salt content)

Coastal Features:

BARRIER ISLAND - long narrow offshore ridges of sand

LAGOON - body of water between the barrier islands and the shoreline (shallow water with lots of mud)

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Why are barrier islands particularly subject to erosion?

THEY ARE THE FIRST TO BE HIT BY WAVES & HURRICANES.

Preserving the Coastline:

While only 5% of the United States is coastal, approximately 50% of the population lives in coastal areas.

We use coastal areas for:

• COMMERCIAL FISHING
• SHIPPING
• RECREATION
• HOUSING DEVELOPMENT

Coastlines are in danger from:

• POLLUTION
• EROSION

LET’S GO SWIMMING!!!

https://docs.google.com/document/d/1cM7e5cjoEHHIZDzRSp041ShEErF3q_-JfdR8pg5JJ58/edit?usp=sharing

Copy and complete:

1. Many of our coastal breeding grounds and shellfish-producing areas have been destroyed by _____________.
2. What is the name of the largest ocean?

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3. What causes the tides?

4. What is the Coriolis Effect?

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5. What causes erosion along the shoreline?

6. What type of ocean waters have the highest salinity?

Tropical waters near the surface (evaporation)

Pollution from land

Pacific

2^nd = Atlantic, 3^rd = Indian, smallest = Arctic

Gravitational pull of the moon

Earth’s spinning on its axis causes currents to move clockwise in N. hemishere and counter-clockwise in S. hemisphere

Wave action

30 Oct 2025

Survey Questions

Please scan the following QR code to take a 1 minute survey, you may have to login with your school email address.

Thank you!

1. What is the pattern of warm and cold ocean currents? (hint: think equator & direction)

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2. What is the relationship between wind currents and ocean currents?

Warm currents start near equator & flow to poles.

Cold currents start near the poles & flow to equator.

Wind currents CREATE/CAUSE the ocean currents.

31 Oct 2025

1. Where does an aquifer get its water supply?

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2. What makes an aquifer able to hold water?

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3. What is an area called in which the water infiltrates/percolates down into the aquifer?

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4. Which way does water flow within an aquifer?

RECHARGE AREAFrom rain on the surface (natural, not paved)

There is an impermeable layer below (aquitard)

Recharge area

Downhill, according to the topography of the land

BONUS WARM-UP

Copy each definition and give the correct word.

1. Rainwater that contains dissolved CO₂

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2. Area where sediment is deposited as a stream reaches the ocean or a large lake

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3. A river that has a steep gradient, few tributaries and is fairly straight

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4. All of the sediments carried by a river, responsible for the majority of erosion

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5. The amount or volume of water in a river

Acid precipitation

delta

Youthful river

Stream Load

Discharge

BONUS WARM-UP

1. List at least 3 conditions in which

groundwater can become contaminated.

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2. How would this be detected?

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3. How can groundwater be cleaned?

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4. IF there is a groundwater contamination in Fayetteville,

• Would Raleigh need to be concerned about its drinking water supply?
• What about cities in SC?

No - uphill

yes

Leaking sewage lines or septic tanks

Leaking underground tanks

A chemical spill that infiltrates into the ground

Contaminated well water

Hmmmm ……………….. ☹

BONUS WARM-UP

BONUS

• HOW does the water actually get into the groundwater?

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1. What factors determine how much water gets into the groundwater?

Soaks in (INFILTRATES) from rainfall on natural ground and PERCOLATES down to accumulate in the aquifer

• amount of space between the soil particles (or rock particles)
• how easily water flows between the particles
• amount of precipitation

Bonus Warm-Up

1. Where in the world right now is there an excess in the water budget? What does that look like?

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2. Where in the world right now is there a shortage in the water budget? What does that look like?

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anywhere with flooding

anywhere with drought

Which would take longer:

1. Boat trip from Boston TO England
2. Boat trip from England TO Boston

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WHY??

You are going against the ocean currents on the way home to Boston. The current is called the Gulf Stream.

BONUS WARM-UP