Watersheds and Stream Order

Watershed

Watershed: The land drained by a river or stream andall of its tributaries.Also known as a Drainage Basin.

Watershed boundaries,or divides, are typicallydefined by the highestelevation that drainsa stream.

Watersheds

The rate at which water travelsthrough a watershed is determinedby factors such as:

its size (total surface area)topography (flat or steep)amount and type of vegetationhuman development

The total amount of water that collects ina river that drains the watershed is calledits Discharge.Discharge is measured in meters3/second.

Total Discharge

Drainage Patterns

Drainage patternsdepend mostlyon: (1) topography;and (2)the type ofrock over whichstreams flow.

Stream Order

Stream Order: a system of classifyingstreams and rivers based on their relationship or position in the drainagenetwork.

Streams at the beginning of the system are calledfirst-order streams. First order streams receive waterdirectly from a source such as a spring, lake,melting snow, etc.

When two first order streams join, the resulting streamis now classified as a second-order stream.

Stream Order

Note: the streamorder will increase only when two like streams join.

Slide 1: Stream Order

Identify the proper stream order for eachof the following locations.

1

2

3

4

Slide #21. Name the mountains thatact as the boundary/divide onthe eastern portion of the Lackawanna River watershed.

2. How many counties comprise the LackawannaRiver watershed?

3. The Lackawanna Rivereventually flows into whichlarger river?

4. Which type of drainage pattern is dominant in the Lackawanna River watershed?

Lackawanna RiverWatershed

Slide 3: Stream Gradient

1

23

1. Place in order from fastest stream velocity to slowest the three locations in the above diagram.2. Which number would best illustrate a youthful stream?3. Which number would best illustrate a mature stream?4. Which number would carry the largest sediments (pebbles, cobbles, boulders)?5. Which location is most likely to have extensive meandering?6. Small sediments like sand and silt will be most likely found at which location?

Slide 4: Mississippi Watershed

1. Name the mountains that cause the divide on the western boundary of the watershed.

2. Name the mountains that cause the divide on the eastern boundary of the watershed.

Slide 5: PA’s Major Watersheds

1. Name the bodies of water that each watershed eventually drains into.2. Which watershed includes theLackawanna River watershed?

Drainage Patterns

#A

#D#C

#BSlide #6

1. Identify the type ofdrainage pattern for each example and;

2. Discuss how, geologically, each pattern forms.

Watershed Questions

1. Describe the relationship between stream order and the size of a watershed.2. Describe how humans can affect a watershed. Give specific examples.3. Describe how increased human development will affect how surface water travels through a watershed.4. Compare a saturated and unsaturated geosphere and how each will influence the rate of surface water flow and discharge of a watershed.

Watershed Dynamics

All of the following watersheds are equal in surface area and receive equal rainfall.Compare and contrast each of the following watersheds: Discuss specifically,

a. the rate of surface water flow through each watersheds (faster or slower)

b. possible disruptions to flow. Give specifics!c. final discharge (more or less)

5. Flat (slope) terrain vs. steep (slope) terrain6. Agricultural vs. forested land7. Rural development vs. urban development