There is a continuous movement of WATER from the atmosphere to the earth’s SURFACES and then back to the ATMOSPHERE. 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 GROUNDWATER: 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. Expenses: EVAPOTRANSPIRATION, RUNOFF Income: PRECIPITATION, CONDENSATION

Factors affecting the local water budget: 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 Finding other supplies of water: DESALINATION: process of removing salt from ocean water.

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. Stream LoadSize of ParticleRate of Stream Erosion Dissolved Load VERY SMALL, DISSOLVED IN WATER SLOW TO NONE Suspended Load FINE SAND AND SILT SLOW Bed load ROCKS & PEBBLES FAST

POTHOLE: bowl-shaped cavity caused by erosion

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

WIND AND WATER GAPS: Movements of the earth’s crust can RAISE orLOWER the surface of the land, and affect STREAM FLOW. WIND GAP: Water eroded notch in a mountain through which no water can flow. WATER GAP: Deep notch left where a stream erodes through mountains where the land is uplifted.

STAGES OF A RIVER SYSTEM: 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 Oxbow lake – a lake is formed from a meander

Meanders – curving of rivers 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

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. DELTA: fan-shaped deposit at mouth of river ALLUVIAL FAN: fan-shaped deposit at bottom of slope on land

DELTA

ALLUVIAL FAN

DeltaAlluvial Fan DEPOSITED IN WATERDEPOSITED ON LAND MADE OF MUD COARSE ANGULAR SAND/GRAVEL FLAT SURFACESLOPING LAND 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 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

Water that seeps into the upper layers of the earth’s crust is called GROUNDWATER. 90 % of earth’s freshwater is underground. In the US, groundwater supplies 20 % of the freshwater needs. Amount of groundwater is 50 times greater than that of rivers and streams. AQUIFER: a body of rock through which large amounts of water can flow and in which much water is stored.

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 SORTEDMEDIUM SORTEDWELL SORTED

The quality of an aquifer depends on: 2. PERMEABILITY - indicates how freely water passes through the open spaces, the spaces must be CONNECTED. 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. 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. 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 o PURIFY o 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 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. 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.

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

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. 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 STALACTITE - cone shaped deposit suspended from the ceiling of a cavern STALAGMITE - cone shaped deposit built up from the floor of a cavern

Results of Chemical Weathering by Groundwater: NATURAL BRIDGE - an arch of rock formed by groundwater erosion (two open places on either side) KARST TOPOGRAPHY - region where the effects of chemical weathering due to groundwater, such as sinkholes and caverns