Watersheds%20and%20Hydrology

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Watersheds and Hydrology

• Whats Water Got to Do with It?
• More water moves through ecosystems than any
  other material
• The materials that it carries and deposits and
  the energy that it expends are major drivers in
  shaping the contour of the land and the habitat
  availability/suitability for organisms.
• A resource that humans cannot live without

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Watersheds and HydrologyLearning Objectives

• Where do we find water?
• What is the hydrologic cycle?
• How many dimensions does a stream have?
• 4 How do we characterize stream water?
• 5 What do we want to know about stream flow?

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Question 1

• Where do we find water?

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Global distribution of water
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Global distribution of freshwater
Water Storage Reservoir Percent () of total Percent () freshwater
Oceans 96.5 0
Ice and Permanent Snow 1.74 68.7
Groundwater 1.7 30.1
Lakes 0.013 0.91
Soil Moisture including permafrost 0.023 0.26
Atmosphere 0.001 0.04
Streams, Rivers, Swamps 0.001 0.036
Biosphere 0.0001 0.003
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Watersheds and Hydrology

• Where do we find water?
• What is the hydrologic cycle?
• How many dimensions does a stream have?
• 4 How do we characterize stream water?
• 5 What do we want to know about stream flow?

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Question 2What is the hydrologic cycle?

• What is the hydrologic cycle?

Precipitation Interception Infiltration Evaporatio
n Transpiration Runoff Ground water

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Watersheds and Hydrology

• Where do we find water?
• What is the hydrologic cycle?
• How many dimensions does a stream have?
• 4 How do we characterize stream water?
• 5 What do we want to know about stream flow?

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Question 3

• How many dimensions does a stream have?

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Question 3

• How many dimensions does a stream have?
• Longitudinal (upstream to downstream)
• Lateral (bank to bank and valley wall to valley
  wall)
• Vertical (water surface to bed to hyporheic to
  ground water)
• Temporal (time seconds to millennia)

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Longitudinal Changes in Streams

• Certain characteristics of streams change
  predictably from upstream to downsteam
• Channels become wider
• Channels become deeper
• Flow becomes slower, but greater in volume

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Longitudinal Changes Reach Scale

• Longitudinal changes are also observed at shorter
  scales than the entire river length
• We call this shorter scale the reach scale
• One example of reach scale changes is the
  pool-riffle pattern found in many streams
  draining areas with medium gradients
• Riffle is an area of rapid flow over coarse
  substrate (sediment) whereas the pool is a slower
  flowing stretch with finer substrate

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Lateral Patterns

• There are also some predictable changes laterally
• The stream has its low flow channel, the low
  point of which is the thalweg
• The stream has banks which define its frequent
  flow limit
• The stream has a floodplain which defines its
  flow limit on less frequent events, annual or
  lesser frequency

Thalweg
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Lateral Patterns

• Some streams and rivers will have a single
  dominant channel while others have a network of
  interwoven channels

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Lateral Features

• As rivers increase in size they will develop a
  complex floodplain system

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Vertical dimensions

• Velocity changes with depth in stream channel

Diagram byEric G. Paterson Department of
Mechanical and Nuclear Engineering The
Pennsylvania State University
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Vertical Features

• Hyporheic (below stream) inter-actions
• Exchanges occur with groundwater just below the
  stream

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Lateral and Vertical Patterns

• In many large alluvial valleys, creatures that
  live in ground water and hyporheic water can be
  found in the subsurface water kilometers from the
  stream.
• In other words the stream extends well beyond its
  visible channel.

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Temporal dimension

• Stream flow changes
• Second by second
• Hourly
• Daily
• Monthly
• Seasonally
• Annually
• Millenniumly
• Channels migrate
• Riparian areas go through disturbance and
  succession
• Seasonal changes in inputs

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Watersheds and Hydrology

• Where do we find water?
• What is the hydrologic cycle?
• How many dimensions does a stream have?
• 4 How do we characterize stream water?
• 5 What do we want to know about stream flow?

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What are the major physical, chemical, and
biological components used to characterize water
quality?
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Selected Important Habitat Factors

• Light
• Substrate
• Temperature
• Oxygen levels
• Flow velocity
• Food availability
• pH
• Hydrologic, nutrient and sediment regimes
• Organic input and transport
• Toxics and other pollutants
• Biological communities

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Influence of temperature on growth rates
1.0
Midges
Daily Growth Rate (mg/day)
0.5
Blackflies
Mayflies
0
0
8
16
24
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Temperature C
Modified from Benke 1993
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Watersheds and Hydrology

• Where do we find water?
• What is the hydrologic cycle?
• How many dimensions does a stream have?
• 4 How do we characterize stream water?
• 5 What do we want to know about stream flow?

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What do we want to know about stream flow?
Question 5

• Magnitude - how much?
• Frequency - how often?
• Timing - when?
• Duration - how long?
• Rate of change how fast?

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1982
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(No Transcript)
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(No Transcript)
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Mean daily flow (cfs)Juanita Creek Water Year
2010
Oct
May
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Mean Monthly FlowsJuanita Creek Water Years
2005-2009
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October flows Juanita Creek
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Oct 13 midnight
Oct 12 midnight
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15 minute flow (cfs) Juanita Creek Monday Oct
29-Wed Oct 31 2012
107
40
20
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November flows Juanita Creek
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Mean May DischargeJuanita Creek
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Hourly vs 15 Minute Measurements
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Mean Daily FlowJuanita Creek (cfs)
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15 minute flowsJuanita Creek May 27-29, 2004
May 28
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Daily vs hourly discharge (cfs)
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(No Transcript)
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Unregulated
Regulated
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Q
Discharge
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How much water is enough?

• Depends on who or what is using the water
• Historically managed for minimum flows (what is
  the minimum flow that keeps fish alive)
• Legal issue of water rights complicates situation

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Examples of where to locate national data for
watersheds and streams

• Watershed data
• EPA Surf your watershed http//www.epa.gov/surf/
• Climate data (national and international)
• http//www.ncdc.noaa.gov/oa/ncdc.html
• Climate data (Washington) http//www.wrcc.dri.edu/
  summary/climsmwa.html

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Examples of where to locate national data for
watersheds and streams

• Stream data- quantity and quality
• USGS Water Resources Data http//water.usgs.gov/da
  ta.html
• Soils data
• http//soils.usda.gov/
• Aquatic biologic indicators
• http//www.epa.gov/bioindicators/

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Take home messages

• Flow regimes play a major role in habitat
• Land-use alters flow paths and storage components
  and hence, flow regimes
• Effects vary with spatial and temporal scales
• Research on which aspects of flow are most
  critical to various biotic responses are in
  progress
• Dont forget the basic processes involved