The Water Above Ground and Underground

Water On Earth –70% of Earth is covered with water –97% of the water is salt water –3% is freshwater –2% is frozen in glaciers –Only 1% of all water on Earth is available to be used for food

Water Water constantly moves between the atmosphere and earth in the water cycle

Water The Sun is the source of energy for the water cycle The Sun is the source of energy for the water cycle

The Water Cycle Runoff: water added to rivers/streams Infiltration: water that soaks into soil Groundwater: water added to water table –Heat from the sun causes water to change from a liquid to a gas (water vapor) –Evaporation is when water changes from a liquid to a gas (water vapor) –The water comes from lakes, streams, and oceans and rises into the atmosphere –Water vapor changes into a liquid in the atmosphere when it cools (CONDENSATION) –When water condenses, clouds form –When the clouds can no longer hold the water vapor, PRECIPITATION occurs

3 Things Rain Does Soaks into the ground Soaks into the ground Runs along the ground to someplace else (runoff) Runs along the ground to someplace else (runoff) Evaporates Evaporates

Runoff Runoff is when water doesn’t soak into the ground or evaporate Runoff is when water doesn’t soak into the ground or evaporate Factors that affect the amount of runoff Factors that affect the amount of runoff –amount of rain & time-span over which it falls –Slope of the land  Steep- more runoff  Gentle- less runoff ---Amount of vegetation-plant roots soak up ---Amount of vegetation-plant roots soak up water water

A River Runs Through It Major rivers are fed by tributaries and divided into drainage basins called watersheds The James River is the largest watershed in Virginia. Mississippi River delta aerial view

River Systems –River systems can be compared to a tree system Stems-runoff Stems-runoff Twigs-small stream Twigs-small stream Branches- large streams Branches- large streams Trunk- river Trunk- river

River Systems –The land area from which a stream gets its water is a drainage basin (watershed) –Largest drainage basin in US- Mississippi River Drainage basin –Rain that falls between the Rocky Mountains and the Appalachian Mountains drains into the Ohio and Missouri rivers –Ohio and Missouri Rivers go into the Mississippi River

Stages of River Development The stage of stream development depends upon the slope of the land over which it flows. River systems usually contain streams in all stages of development Outer edges-young; bottom of mountains and hills- mature; lowest point of drainage basin-old Young Mature Old Oxbow lakes form when meanders get cut-off by deposition

Young Rivers  Steep slope  Found in mountainous & hilly areas  Rapids and waterfalls  Lots of energy  Bottom eroded

Mature Streams  Develop curves (meanders)  Gradual slope  No rapids and waterfalls  Less swift  Sides are eroded  Water flow less swiftly in shallow areas because of friction and more swiftly in deep areas and the fast water erodes the sides  Floodplain develops

Old Streams  Very slow  Curves change  Ox bow lakes form when meanders get cut off by deposition  Old stream Example: Mississippi R.  Floodplain gets wider

River Loads and Deposits Rivers carry lots of rocks and sediment with them, called its load 1.Bed load : pebbles and boulders on the stream bottom 2.Suspended load : small rocks and pieces of soil that make the river look muddy 3.Dissolved load : elements dissolved in the water Eventually, the river will deposit its load, which is called alluvium. Alluvial fans form at the bottom of a slope on land; deltas form when a stream runs into a larger body of water such as an ocean or a gulf Alluvial Fan Nile River delta

Groundwater The water we find underground is called groundwater ! The water we find underground is called groundwater ! Through precipitation, water will infiltrate into the soil and eventually reach the water table Through precipitation, water will infiltrate into the soil and eventually reach the water table Water percolates through rock Water percolates through rock

Porosity Porosity is the amount of pores a rock has Porosity is the amount of pores a rock has Pores are located between fragments and pieces of weathered rock. Pores are located between fragments and pieces of weathered rock. Water collects in the pores. Water collects in the pores. A system of connecting pores transport water through the ground. A system of connecting pores transport water through the ground.

Permeability Permeability is the ability of water to pass through rock. Permeability is the ability of water to pass through rock. If water can pass easily, we say the soil or rock is permeable If water can pass easily, we say the soil or rock is permeable If it cannot pass easily, it is impermeable. If it cannot pass easily, it is impermeable. Groundwater will keep going down to lower elevations until it reaches an impermeable layer Groundwater will keep going down to lower elevations until it reaches an impermeable layer

Water is Stored in Rocks? A layer of rock that stores and allows the flow of groundwater is called an aquifer A layer of rock that stores and allows the flow of groundwater is called an aquifer Rock layers need to be porous, which means it must have open spaces between the sediments for water to pass through Rock layers need to be porous, which means it must have open spaces between the sediments for water to pass through The best rock types for aquifers are sandstone, limestone, or a sandstone/gravel mix The best rock types for aquifers are sandstone, limestone, or a sandstone/gravel mix

Aquifers –Zone of saturation is the layer that the pores in the rock are completely filled with water –Zone of aeration is the layer of rock where it is partially filled with both water and air –Water table is the upper surface of the zone of saturation

Wells Wells are drilled into the zone of saturation Wells go dry b/c the water table drops Cone of depressions form around a well b/c water is being pumped out faster than it can be replaced

Artesian Wells Artesian well- doesn’t need pump to remove water –Needs a sloping aquifer between 2 impermeable layers –Water goes in at high end & well drilled at lower part

Springs Water table meets earth’s surface Water table meets earth’s surface Commonly found on hillsides Commonly found on hillsides Hot springs are springs in which the water is heated by magma Hot springs are springs in which the water is heated by magma Geyser is a hot spring that erupts periodically Geyser is a hot spring that erupts periodically

Hotspring

Geysers- Erupting Hotsprings

Limestone Caves

KARST TOPOGRAPHY Just like rivers erode the land at the surface, groundwater erodes rocks below the surface Just like rivers erode the land at the surface, groundwater erodes rocks below the surface Limestone is easily dissolved by acidic groundwater; limestone has calcite in it Limestone is easily dissolved by acidic groundwater; limestone has calcite in it Acidic groundwater moves through the cracks in the rock and forms openings called caves Acidic groundwater moves through the cracks in the rock and forms openings called caves When the roof of a cave collapses, a sinkhole forms When the roof of a cave collapses, a sinkhole forms The Valley & Ridge physiographic province has large limestone deposits, caves, and sinkholes The Valley & Ridge physiographic province has large limestone deposits, caves, and sinkholes

Deposits in caves Features form because water with calcite drips; the water evaporates leaving the calcite deposits behind Features form because water with calcite drips; the water evaporates leaving the calcite deposits behind

Stalactites & Stalagmites

Stalagmites Stalagmites are on the ground of the cave Stalagmites are on the ground of the cave Remember “g” for ground Remember “g” for ground

Stalactites Stalactites are calcite deposits on the top of the cave Stalactites are calcite deposits on the top of the cave Remamber “c” for ceiling Remamber “c” for ceiling

Stalactites & Stalagmites

Column Columns form when the a stalactite and a stalagmite meet. Columns form when the a stalactite and a stalagmite meet.