Bio 346 - Freshwater Eco. (Chpt 29) --> Reservoirs

Question 1

What are 3 things reservoirs are primarily used for?

Answer 1

1. Irrigation
2. Water supply
3. Fish farming

Question 2

How are reservoirs typically constructed?

Answer 2

Constructed by damming rivers in regions where evaporation approaches or exceeds precipitation with the water typically derived from local rivers during rainy periods

Question 3

What are large volumed reservoirs primarily used for?

Answer 3

Hydroelectric power generation

- Constructed where precipitation can be low or high to have river discharge

Question 4

What has major ramifications on reservoirs for river discharge and its timing for sediment and nutrient retention behind dams?

Answer 4

Water retention

Question 5

What are 3 things that happens to reservoirs at lower latitudes?

Answer 5

1. Longer growing season
2. Longer stratification period
3. Higher water temp
4. Lack of ice cover
5. Receives a much greater put of inorganic matter from their well-vegetated catchments than dimicdic lakes

Question 6

Epilimnion

Answer 6

The upper layer of water in a stratified lake

Question 7

Thermocline

Answer 7

A steep temp gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temps

Question 8

Hypolimnion

Answer 8

The lower layer of water in a stratified lake

- Typically cooler than the water above

Question 9

Lacustrine (define)

Answer 9

In the deepest region downstream from the transition zone and where strictly limnteic processes dominate

Question 10

Riverine Zone (define)

Answer 10

An island or coastal area comprising both land and water, characterized by limited land lines of communication with extensive water surface and/or inland waterways that provide natural routes for surface transportation and communications

Question 11

Transition zone (define)

Answer 11

Area between 2 states (land and water)

Question 12

What does increase in erosion lead to? (5 things)

Answer 12

1. Degradation of the original river channel
2. Effects sediment characteristics
3. Lowers the groundwater table
4. Impacts the feeding and spawning habitats of fishes
5. Impacts the biota of the rivers in general

Question 13

Whats happens when you trap sediment and their absorbed nutrients behind dams?

Answer 13

It removes the rivers role as a fertilizing agent to previously undisturbed and seasonally flooded wetlands, crop-growing areas downstream and the receiving estuaries
- Dams act as barriers

Question 14

What kind of sediment is in high flowing waters?

Answer 14

Course sediment

Question 15

What kind of sediment is in low flowing waters?

Answer 15

Fine sediment

Question 16

What do flood control dams do?

Answer 16

Reduce seasonal variations in discharge

Question 17

What are 6 factors both artificial and natural lakes lie along?

Answer 17

1. Gradients of climate
2. Geology
3. Morphometry
4. Flushing
5. Chemistry
6. Biology

Question 18

What are the 3 types of reservoirs?

Answer 18

1. Mainstream reservoirs
2. Tributary storage reservoirs
3. Mainstream storage reservoirs

Question 19

Mainstream reservoirs (4 things)

Answer 19

• Most river like (WRT = days–>weeks)
• Constructed to generate electricity
• Experience no temp stratification
• Experience no seasonal lowering of the water

Question 20

Tributary storage reservoirs (4 things)

Answer 20

• Longest WRT (month–> years)
• Greatest possibility of temp stratification
• Built on small rivers
• Usually built for flood control and irrigation

Question 21

Mainstream storage reservoirs (2 things)

Answer 21

• Intermediate WRT (usually a few months)

- Its more lotic during high runoff periods and switches to more lentic at other times

Question 22

When does washout of phytoplankton commence?

Answer 22

At lower WRT in turbid, deeply mixed or cold reservoirs where conditions for photosynthesis are much less favourable than in shallow systems of low turbidity at summer temps

Question 23

Larger organisms have what kind of growing rate and doubling time?

Answer 23

• Slower

- Longer

Question 24

Riverine Zone (7 things)

Answer 24

1. Narrow
2. High flow and rapid water flushing
   - High turbidity
3. High suspended spoils
4. Low light
   - limits planktonic pp, but high benthic pp
5. Relatively high nutrients
6. Growth rate is less than flushing rate
7. Coarse sediment

Question 25

Transition zone (7 things)

Answer 25

1. Broader
2. Reduced flow and flushing
   - Low turbidity
3. Reduced suspended solids
4. Increased light availability
   - High planktonic pp, low benthic pp
5. Low nutrient supply
6. Fine sediment
7. Dissolved O2 is high when unstratified and low when stratified

Question 26

Lacustrine zone (7 things)

Answer 26

1. Broad and deep
2. Little flow and slowest water flushing
3. Relatively clear = good lighting (better higher up)
4. Nutrient supply by internal recycling
5. Growth rate is higher than flushing rate
6. Fine sediment
7. Dissolved O2 is variable

Question 27

What is very important about resident time?

Answer 27

It creates a stable community

Question 28

What does shortening of the resident time do?

Answer 28

Cant double up which results in low transparency (due to low grazers)

Question 29

Storage reservoirs experience what annually?

Answer 29

Drawdown

- which is a primary response to seasonably changing needs for hydroelectric power or irrigation water

Question 30

What is aging linked to?

Answer 30

1. Oxidation of the terrestrial vegetation
2. Flooded soil organic matter
3. Shifts in the composition and abundance of biota during its transition from a primary riverine (lotic) to a lake (lentc) assemblage

Question 31

Trophic upsurge

Answer 31

During the early years after it is filled, nutrient [ ] and productivity at all trophic levels are usually elevated

Question 32

What percent of global water is fresh?

Answer 32

3%

- drinking, irrigation and industrial use

Question 33

How much fresh of the 3% of freshwater is hard to use? And why?

Answer 33

• 99.7%

- Held in glaciers and deep aquifers

Question 34

What does water balance depend on?

Answer 34

Ratio between inflow, precipitation and evaporation

Question 35

What can the balance of water be effected by?

Answer 35

1. Dams or diversion
2. Climate change
   - Resulting open systems into closed systems with no outflow

Question 36

How are salts and chemicals transported?

Answer 36

By wind

Question 37

Health consequences (5 things)

Answer 37

1. Higher child mortality
2. Lower life expectancy (64 –> 51 years)
3. Increase in cancer
4. DNA damage
5. Birth abnormalities

Question 38

How do you stabilize lake levels?

Answer 38

Increase water input into basin

Question 39

What are 5 problems due to dams?

Answer 39

1. Human displacement
2. Blockage of fish passage and transportation
3. Holdback of sediment, erosion downstream
4. Changes downstream quality
5. Reduced productivity

Question 40

3 Gorges dam in China

Answer 40

• Flood control, hydro power, transportation, water supply
• Loss of agricultural land, historical sites
• Local climate, public health, soil stability

Question 41

Dam diversion (Past and future problems)

Answer 41

• Largely political
• Careful consideration of economics
• Education of public as to value of water and increase cost
• International co-operation efforts
• Conservation
• Re-use

Question 42

What are some impacts due to dams?

Answer 42

1. Increase in accumulation of Hg in fish and neurodegenerative symptoms in humans

Question 43

What happens to the loading of oceans and salinity if the creation of dams increase to meet the increasing rate of consumption?

Answer 43

• Loading to oceans will decrease

- Salinity would increase as a result