Field trip liability sheets

Lec 4: Dams & Reservoirs

I. Why Have Dams & Reservoirs?II. Comparisons to Natural Lakes III. Reservoir ZonesIV. Alteration of Habitat & CommunitiesV. Serial DiscontinuityVI. Water Turnover and Trophic State

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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II. Comparisons to Natural Lakes -Reservoirs tend to be ‘dendritic’

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II. Comparisons to Natural Lakes

• Much larger

• Drain more area / surface area

• Are deeper

• Shorter water residence time • Higher nutrient loading rates

Compared to naturallakes, reservoirs are:

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U.S.

II. Comparisons to Natural Lakes

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‘Zones’

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III. Reservoir ‘Zones’

Morphology‘Flow’

ClarityNutrients

PP limitationCell losses

Allo/AutoTrophic St.

Longitudinal zonation in deep reservoirsoccupying a well-defined river valley

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Morphology

Clarity

Nutrients

PP limitation

Allo/Auto

Longitudinal Gradients across Zones

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• 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.

IV. Alteration of Habitat & Communities

1. Dams homogenize downstream habitat

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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?)

IV. Alteration of Habitat & Communities

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• 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…)

V. Serial Discontinuity

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VI. Water Turnover and Trophic State

•Change in Y

•Change in X

•Change in [P]

•Turnover rate vs. plankton pop’n growth rates

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Longer residence time, more likely P will be sedimented

HIDDEN DAM (HENSLEY)

Station ID HID Elevation 561' ftRiver Basin FRESNO R County MADERAHydrologic Area SAN JOAQUIN RIVER Nearby City RAYMONDLatitude 37.2000°N Longitude 119.9170°WOperator 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.

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http://cdec.water.ca.gov/cgi-progs/plotDaily?staid=HID

43,560 ft3 / AFHIDDEN DAM (HENSLEY) (HID)Located at 561 feet in the FRESNO R basin.