The Water Above Ground and Underground Water On
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 constantly moves between the atmosphere and earth in the water cycle
Water • 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 • Runs along the ground to someplace else (runoff) • Evaporates
Runoff • Runoff is when water doesn’t soak into the • ground or evaporate Factors that affect the amount of runoff – amount of rain & time-span over which it falls – Slope of the land v Steep- more runoff v Gentle- less runoff ---Amount of vegetation-plant roots soak up 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 • Twigs-small stream • Branches- large streams • 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 Mature Young Old Oxbow lakes form when meanders get cut-off by deposition 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 hillsmature; lowest point of drainage basin-old
Young Rivers v. Steep slope v. Found in mountainous & hilly areas v. Rapids and waterfalls v. Lots of energy v. Bottom eroded
Mature Streams v Develop curves (meanders) v Gradual slope v No rapids and waterfalls v Less swift v Sides are eroded v Water flow less swiftly in shallow areas because of friction and more swiftly in deep areas and the fast water erodes the sides v Floodplain develops
Old Streams v v v 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! Through precipitation, water will infiltrate into the soil and eventually reach the water table Water percolates through rock
Porosity • Porosity is the amount of pores a rock • • • has Pores are located between fragments and pieces of weathered rock. Water collects in the pores. A system of connecting pores transport water through the ground.
Permeability • • Permeability is the ability of water to pass through rock. If water can pass easily, we say the soil or rock is permeable If it cannot pass easily, it is impermeable. 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 • 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
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 Commonly found on hillsides Hot springs are springs in which the water is heated by magma 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 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 When the roof of a cave collapses, a sinkhole forms 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
Stalactites & Stalagmites
Stalagmites • Stalagmites are on the • ground of the cave Remember “g” for ground
Stalactites • Stalactites are calcite • deposits on the top of the cave Remamber “c” for ceiling
Stalactites & Stalagmites
Column • Columns form when the a stalactite and a stalagmite meet.
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