How many rivers are in the US?
over 250,000
What is a tributary?
A tributary is a river that feeds into another river, instead of ending in a lake, pond or ocean
If a river is large, where does most of its water come from?
Where does downstream always point?
to the end of a river, or the mouth
What is the mouth of the river?
the end
What is upstream?
Upstream always points to the river’s source, or headwaters
What is “headwaters”?
the river’s source
Where is River Right?
As you look downstream, your right hand
Where is river left?
as you look downstream, it is on your left
What is the beginning of a river called?
Give examples of headwaters.
spring from underground; marshy areas fed by snow; thousands of small streams coming together; froma lake or pond
What three things shape a river channel?
how much water has been flowing through it for how long; what types of soil or rock it flows over; what vegetation it flows through
How are the bends in a river called meanders formed?
water taking away soil on the outside of a river bend and laying it in the inside of a river bend over time
What is the land next to the river called?
What is the riparian zone?
streamside trees and other vegetation
Why is the riparian zone important?
It is a nutrient-rich area for wildlife, replenished by the river when it floods
In the West, what does the riparian zone provide?
habitat for bird species
What zone protects the river from erosion during floods, and filters polluted run-off from cities and farms?
the riparian zone
What are floodplains?
low, flat areas next to rivers, lakes and coastal waterways that sometimes flood if the water is high
What do animals and plants that live in floodplains often need to survive reproduce?
How do floodplains benefit people?
They absorb floodwaters that would otherwise rush downstream and flood communities and property
What is the end of a river called?
mouth or delta
What shape is a delta?
What happens at the delta?
the land flattens and the water loses speed, spreading into a fanshape
Where are deltas usually found?
where the river meets an ocean, lake or wetland
What happens as the river slows down?
it cannot carry sediment or sand
How do deltas build fertile farmland?
when the river slows, sand and sediment is dropped which contain nutrients that help the soil
Why are deltas called ‘cradles of civilization’?
they help build fertile farmland
Where is the breeding and nesting grounds of hundreds of species of fish and birds?
What are wetlands?
lands soaked with water from nearby lakes, rivers, oceans, and underground springs
Are wetlands wet all year?
some are, but somedry out
What do wetlands do with floodwaters?
protect communities by storing and slowly releasing floodwaters
How do wetlands provide clean water?
by filtering pollution
What is the flow?
flow is the water running in a stream or river
What are two important aspects to flow?
amount of water that flows in the river, and how water moves through the channel
Why can building a dam hurt the flow of a river?
it blocks the water from flowing
What is a river’s pulse?
natural ‘ups and downs’ of a river; example: some parts flow faster than other parts; the river stops flowing completely