Field trip liability

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Field trip liability sheets
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Lec 4 Dams Reservoirs
I. Why Have Dams Reservoirs? II. Comparisons
to Natural Lakes III. Reservoir Zones IV.
Alteration of Habitat Communities V. Serial
Discontinuity VI. Water Turnover and Trophic State
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I. Why Dams Reservoirs?

• Water storage for Irrigation, municipal use
• Flood control
• Electric power generation
• Recreation (both within downstream)
• Sediment trapping
• Water quality improvement
• Navigation

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• Comparisons to Natural Lakes
• -Reservoirs tend to be dendritic

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II. Comparisons to Natural Lakes
U.S.
Compared to natural lakes, reservoirs are

• Much larger
• Drain more area / surface area
• Are deeper
• Shorter water residence time
• Higher nutrient loading rates

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II. Comparisons to Natural Lakes
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Zones
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III. Reservoir Zones
Longitudinal zonation in deep reservoirs occupying
a well-defined river valley
Morphology Flow Clarity Nutrients PP
limitation Cell losses Allo/Auto Trophic St.
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Longitudinal Gradients across Zones
Morphology Clarity Nutrients PP
limitation Allo/Auto
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IV. Alteration of Habitat Communities 1.
Dams homogenize downstream habitat

• Controlled water releases prevent
• - High discharge events (spates)
• - Variation in discharge
• More amenable to generalists than specialists
• In a stable setting, generalists will always
  out-
• compete specialists
• This means that dams put on smaller,
  unpredictable
• streams tend to decrease species diversity
  and
• favor generalists.

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IV. Alteration of Habitat Communities

• 2. Migration
• Fish are more seriously affected by dams than
  inverts
• Migratory fish are unable to reach their spawing
  grounds
• Quality of spawning habitat is reduced (/-
  discharge)
• The inability to migrate affects fish
  distributions (salmon, trout, sturgeon).
• 3. Salinization of coastal wetlands (How?)

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V. Serial Discontinuity

• The Serial Discontinuity Concept (SDC) describes
  how dams reset or interrupt physical, chemical,
  and biological processes
• Two components
• Discontinuity distance which is the distance
  below the dam it takes a measured variable to
  return to its state above the impoundment. It is
  also expressed in terms of stream order above
  the dam it may be a 5th order stream, while below
  it has conditions more similar to when the river
  use to be a 2nd order stream (where?)
• Intensity which is the degree of change measured
  in magnitude or absolute units (to what degree)

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VI. Water Turnover and Trophic State

• Change in Y
• Change in X
• Change in P
• Turnover rate vs. plankton popn growth
  rates

Longer residence time, more likely P will be
sedimented
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HIDDEN DAM (HENSLEY) Station ID HID Elevation
561' ft River Basin FRESNO R County
MADERA Hydrologic Area SAN JOAQUIN RIVER Nearby
City RAYMOND Latitude 37.2000N Longitude
119.9170W Operator US Army Corps of Engineers
Data Collection DATA EXCHANGE The following data
types are available online. Select one of the
links below to retrieve recent data. EVAPORATION,
PAN INCREMENT, inches (daily) From 01/02/1994 to
present. PRECIPITATION, INCREMENTAL, inches
(daily) From 01/04/1988 to present. RESERVOIR
ELEVATION, feet (daily) From 01/01/1985 to
present. RESERVOIR INFLOW, cfs (daily) From
01/02/1994 to present. RESERVOIR OUTFLOW, cfs
(daily) From 10/01/1993 to present. RESERVOIR
STORAGE, af (daily) From 01/01/1985 to
present. RESERVOIR, STORAGE CHANGE, af (daily)
From 10/03/1993 to present. RESERVOIR, TOP
CONSERV STORAGE, af (daily) From 10/20/2000 to
present. TEMPERATURE, AIR MAXIMUM, deg f (daily)
From 01/02/1994 to present. TEMPERATURE, AIR
MINIMUM, deg f (daily) From 01/02/1994 to
present. WIND, TRAVEL LENGTH, miles (daily) From
01/09/1994 to present. RESERVOIR, SCHEDULED
RELEASE, cfs (event) From 10/01/1995 to
present. PRECIPITATION, ACCUMULATED, inches
(hourly) From 12/07/1988 to present. RESERVOIR
ELEVATION, feet (hourly) From 12/07/1988 to
present. RESERVOIR INFLOW, cfs (hourly) From
12/07/1988 to present. RESERVOIR INFLOW-LAST 6HR
AVG, cfs (hourly) From 03/07/2000 to
present. RESERVOIR OUTFLOW, cfs (hourly) From
12/07/1988 to present. RESERVOIR STORAGE, af
(hourly) From 12/07/1988 to present. RESERVOIR
STORAGE, af (monthly) From 10/01/1975 to present.
http//cdec.water.ca.gov/cgi-progs/plotDaily?staid
HID
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HIDDEN DAM (HENSLEY) (HID) Located at 561 feet
in the FRESNO R basin.
43,560 ft3 / AF