1. Physical Characteristics of streams
Unit 1: The Hydrosphere

2. Temperature Varies with season, time of day, and amount of sunlight
Land use: what did I say about trees that provide shade?
Runoff gets warmed as well
Warmer temperatures have serious impacts on Dissolved Oxygen
Concentrations decrease
Inc. rates of metabolism, requiring more DO
Once again, remind them this is connected with the biology and chemistry

3. Turbidity Review: what is turbidity? Effects of high turbidity
Clogging gills of fish reducing the amount of oxygen they can take in
Absorb more sunlight increasing
temperature
Fish spawning
Decreased amount of light
Can be caused by suspended sediments AND single-celled algae!
5 percent inc. in turbidity can lead to a 50 percent decrease in the number of fish eggs!

4. Stream Order
A common stream classification system to refer to the size of the stream and its tributaries
First order is small with no tributaries; occur at “top” of watershed
When two first order streams come together, they form a second order stream!
Two seconds? What about a second and a first?
Why is this important?
Tells us where streams occur
Tells us characteristics of streams (velocity, slope, substrates), which in turn give us information about the biology and chemistry

6. Rates of Flow
Streamflow/discharge – the volume of water flowing past a certain point over a designated period of time (m3/sec)
Small stream: 1 m3/sec
Amazon River: 200,000 m3/sec
Can be calculated by multiplying the cross sectional (vertical) area by the velocity (easy measure)
Measured regularly by the U.S. Geological Survey by using an equation specific to each site

7. discharge Changes Over Time
Represented by a Hydrograph
Higher right after a
rain or snow storm
(additional water)
Lower during a
dryspell

8. Impact of Impervious Surfaces
Review: where is percolation into the groundwater greater, natural ground cover, or urban ground cover?
In urban areas, there is more runoff into a body of water
Therefore, discharge in an urban watershed reaches a higher peak, indicating higher flood levels
Negative impacts on organisms:
Increased erosion which destroys habitats
Decreased percolation » less groundwater = BAD during dryspells