Field trip liability sheets Lec 4 Dams Reservoirs

Field trip liability sheets

Lec 4: Dams & Reservoirs I. III. IV. V. VI. Why Have Dams & Reservoirs? Comparisons to Natural Lakes Reservoir Zones Alteration of Habitat & Communities Serial Discontinuity 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 2

II. Comparisons to Natural Lakes -Reservoirs tend to be ‘dendritic’ 3

II. Comparisons to Natural Lakes Compared to natural lakes, reservoirs are: U. S. • Much larger • Drain more area / surface area • Are deeper • Shorter water residence time • Higher nutrient loading rates 4

II. Comparisons to Natural Lakes 5

‘Zones’ 6

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. 7

Longitudinal Gradients across Zones Morphology Clarity Nutrients PP limitation Allo/Auto 8

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 outcompete specialists • This means that dams put on smaller, unpredictable streams tend to decrease species diversity and favor generalists. 9

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? ) 10

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 5 th order stream, while below it has conditions more similar to when the river use to be a 2 nd order stream (where…? ) • Intensity which is the degree of change measured in magnitude or absolute units (to what degree…) 11

12 VI. Water Turnover and Trophic State • Change in Y • Change in X • Change in [P] • Turnover rate vs. plankton pop’n growth rates Longer residence time, more likely P will be sedimented

HIDDEN DAM (HENSLEY) http: //cdec. water. ca. gov/cgi-progs/plot. Daily? staid=HID Station ID HID Elevation 561' ft River Basin FRESNO R County MADERA Hydrologic Area SAN JOAQUIN RIVER Nearby City RAYMOND Latitude 37. 2000°N Longitude 119. 9170°W 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 6 HR AVG, cfs (hourly) From 03/07/2000 to present. RESERVOIR OUTFLOW, cfs (hourly) From 12/07/1988 to present. RESERVOIR STORAGE, af (monthly) From 10/01/1975 to present. 13

HIDDEN DAM (HENSLEY) (HID) Located at 561 feet in the FRESNO R basin. 43, 560 ft 3 / AF