In this review, material that is underlined is what
everyone should know for this unit. There will be
opportunity on the test to share about other material
shared in this review. Understanding of extra material
will give students opportunity to show advanced
understanding of the Land and Water Unit.
The Water Cycle
You should be able to describe precipitation, condensation and evaporation.
To show advanced, you should be able to describe transpiration, infiltration, and
groundwater flow.
Are the following forms of water a solid, a liquid, or a gas?
Rain = liquid
clouds = liquid
ice = solid
River = liquid
steam = gas
snow = solid
WHAT IS A RIVER SYSTEM?
Every river is part of a larger system-a watershed, which is the land drained by a river and its
tributaries. Rivers are large natural streams of water flowing in channels and emptying into
larger bodies of water. This diagram shows some common characteristics of a river system.
Every river is different,
however, so not all rivers may
look exactly like this
illustration.
The river source, also called
the
head, is the beginning of
a river. Often located in
mountains, the source may be
fed by an under- ground spring,
or by runoff from rain,
snowmelt, or glacial melt.
The
mouth is the place
where a river flows into a larger
body of water, such as another
river, a lake, or an ocean.
Upstream is in the direction of
or nearer to the source of a
river.
Downstream is in the direction
of or nearer to the mouth of a river.
Wetlands are low-lying areas saturated with water for long enough periods to support vegetation
adapted to wet conditions. Wetlands help maintain river quality by filtering out pollutants and
sediments, and regulating nutrient flow.
A fully-developed floodplain is relatively flat land stretching from either side of a river, which
may flood during heavy rain or snowmelt. Built of materials deposited by a river, floodplain soil
is often rich in nutrients and ideal for growing food.
A
tributary is a smaller stream or river that joins a larger stream or main river.
A watershed boundary, also called a drainage divide, marks the outer- most limit of a
watershed. A watershed is a tract of land drained by a river and its tributaries. Anything that
affects a watershed may eventually impact its tributaries and river as well as the water body at
the mouth of the river. People's actions within a watershed can affect the overall quality of its
rivers.
The main river is the primary channel and course of a river.
A meander is a loop in a river channel. A meandering river winds back and forth, rather than
following a straight course.
The delta is the buildup of deposited soil at the mouth of the river.
You should be able to draw a river and label the head, the mouth and the tributaries.
For advanced you will be able to add labels of other parts of rivers.
An area that has gone a long period of time without rain is suffering from a
drought.
An area that has received too much rain in a short period of time may be
suffering from a
flood.
What is in soil?
Pieces of Gravel are often found in soil. Gravel are rock fragments that
can be anywhere from 2 mm to 6.4 cm long.
Components of Soil
Sand is the largest particle in the soil other than gravel. When
you rub it, it feels rough. This is because it has sharp edges.
Sand doesn't hold many nutrients.
Silt is a soil particle whose size is between sand and clay. Silt
feels smooth and powdery. When wet it feels smooth but not
sticky.
Clay is the smallest of particles. Clay is smooth when dry and
sticky when wet. Soils high in clay content are called heavy soils.
Clay also can hold a lot of nutrients, but doesn't let air and
water through it well.
Particle size has a lot to do with a soil's drainage and nutrient
holding capacity. To better understand how big these three soil
particles are, think of them like this. If a particle of sand were
the size of a basketball, then silt would be the size of a
baseball, and clay would be the size of a golf ball. Line them all up, and
you can see how these particles compare in size.
Also in soil…
There is also humus in soil. Humus is organic material – made from
decaying plant and animal material. It is generally very dark, and holds
lots of nutrients. It will often float when a lot of water is added.
There is also air and water in soil.
What is
erosion?
 The process by which earth materials are broken down
and moved from place to place.
 In our stream tables, we saw that water moved the soil
from one end of the table to the other.
 The larger streams moved the bigger particles of gravel
and sand. The smaller stream mainly moved the sand
and clay.
 Erosion changed our flat surface of soil into a canyon,
or rivulet,
Why do humans build dams?
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To create electricity
Provide water for farmers
To provide a water supply for large cities
To create habitats for fish and wildlife.
To restore beaches when water is released.
To prevent flooding.
How does slope effect the way water moves?
What happens to the water and the land?
A lentic system
Land is mostly flat… the water will move very
slowly or be still. The land soaks up the water or the
water evaporates into the sky. When land is mostly flat, a
pond, lake or wetlands area may often form.
A lotic system
Land has a steep hill… the water will move very fast
down the hill, perhaps creating a waterfall. The fast
moving water will erode the land and pull the land down
toward the bottom of the hill. Rivers and streams have
formed due to water flowing down hills that have a slope
rather than flat land.
People plant grass and trees on sloped hills to help protect
the land from erosion.
Erosion makes canyons, caves and
sinkholes.
Deposition makes beaches and deltas.