Groundwater and Surface
Water in a Watershed
Human Activity
7.8C- model the effects of human activity on groundwater and surface water
in a watershed.
What is Groundwater?
 Groundwater is water that comes from
the ground. Sounds easy, doesn't it?
Amazingly, many people use
groundwater but don't even know it. In
fact, half of everyone in the United
States drinks groundwater everyday!
Groundwater is even used to irrigate
crops which grow food for tonight's
dinner.
Where Does Groundwater
Come From?
 Groundwater comes from rain, snow, sleet,
and hail that soaks into the ground. The water
moves down into the ground because of
gravity, passing between particles of soil,
sand, gravel, or rock until it reaches a depth
where the ground is filled, or saturated, with
water. The area that is filled with water is
called the saturated zone and the top of this
zone is called the water table. Makes sense,
doesn't it? The top of the water is a table! The
water table may be very near the ground's
surface or it may be hundreds of feet below.
Do YOU Live on a Watershed?
 Do ya? Huh? Do ya???
 What do you think of when you hear
the term “watershed”?
Watershed Diagram
What
is
a
Watershed?
 Watershed- the land area from which surface runoff
drains into a stream channel, lake, reservoir, or other
body of water; also called
http://www.youtube.com/embed/dUlAANVBYHM
 a drainage basin.
A BASIN is the entire geographical area drained by a
major river and its intersecting streams.
 In every watershed, small streams flow into larger
streams, which flow into rivers, lakes, and bays. The
smallest streams at the outer limits of a watershed are
called headwaters. Headwaters are the source and
upper part of a stream.
What is a Watershed?
 These headwater streams have no
tributaries and are called first order
streams. All other streams have tributaries.
Second order streams form when first order
streams meet.
A tributary is a stream that flows into a
larger stream or other body of water.
Do WE Live on a Watershed?
 All land is a part of some watershed!
Not only do streams and rivers flow to a
collecting basin, but so too do the
impacts that humans have upon those
waterbodies. Human activities that
impact the quality of the river water
flowing into a basin also impact the
basin itself.
YOUR Watershed!
http://www.brazos.org/images/Basin-Topo.pdf
Think About This:
 Think about this: have you ever dug a hole in
sand next to an ocean or lake? What
happens? As you're digging, you eventually
reach water, right? That water is
groundwater. The water in lakes, rivers, or
oceans is called surface water...it's on the
surface. Groundwater and surface water
sometimes trade places. Groundwater can
move through the ground and into a lake or
stream. Water in a lake can soak down into
the ground and become groundwater.
Where is Groundwater Stored?
 Groundwater is stored in the
ground in materials like gravel
or sand. It's kind of like the
earth is a big sponge holding
all that water. Water can also
move through rock formations
like sandstone or through
cracks in rocks. An area that
holds a lot of water, which can
be pumped up with a well, is
called an aquifer. Wells pump
groundwater from the aquifer
and then pipes deliver the
water to cities, houses in the
country, or to crops.
How Does Groundwater Fit in
the Water Cycle?
 The water cycle is also known as the
hydrologic cycle- the same water is
cycled on earth since the beginning of
time.
 Where does this water come from?
Steps of the water cycle:
 1) Evaporation- happens when heat is added to
water molecules and causes them to slowly transform
from liquid into vapor.
 What phase change occurs?
 2) Condensation- water vapor travels up into the
atmosphere and condenses, forming clouds.
 3) Precipitation- Water vapor in the clouds
condense more and more until they form water
droplets. The clouds get heavy and cause the droplets
to fall as rain, sleet, snow, or hail.
Steps of the water cycle:
 4) Infiltration/Runoff- Infiltration means water soaks into
the ground (called recharge). Runoff is when water flows
from high points of ground to low points, due to gravity.
 Down, down, down the water goes through the soil until it
becomes groundwater and is stored in the aquifer below.
Once the water has joined the aquifer, it doesn’t stop there.
The groundwater slowly moves through the spaces and
cracks between the soil particles on its journey to lower
elevations. This movement of water underground is called
groundwater flow. Eventually, after years of underground
movement, the groundwater comes to a discharge area
where it enters a lake or stream. There, the water will once
again be evaporated and begin the cycle again. Water has
been transported through the water cycle for millions of
years and will continue this cycle forever. In the water cycle,
water is constantly on the move.
What Happens to
Groundwater?
 Most groundwater is clean, but groundwater can
become polluted, or contaminated. It can
become polluted from leaky underground tanks
that store gasoline, leaky landfills, or when
people apply too much fertilizer or pesticides on
their fields or lawns. When pollutants leak, spill,
or are carelessly dumped on the ground they can
move through the soil. Because it is deep in the
ground, groundwater pollution is generally
difficult and expensive to clean up. Sometimes
people have to find new places to dig a well
because their own became contaminated.
Human Activity
 Human activities commonly affect the
distribution, quantity, and chemical quality of
water resources.
 Human activity can include: agriculture,
urban development and industry, drainage of
low-lying areas, construction of levees, dams,
or reservoirs and removal of vegetation from
flood plains.
Agriculture
 Irrigation removes groundwater or
surface water for use on crops then
carries it away.
 Chemicals, pesticides or fertilizers, are
applied to croplands and eventually
make their way into watersheds can
lead to an overgrowth of algae in water.
Urban Development
 Discharge from sewage-treatment
plants, industrial facilities, and storm
water drains, leaking fluid storage
tanks, septic tanks, and landfills can
also add to the contamination.