Reservoirs

Question 1

Purpose of reservoirs - general

Answer 1

regulate flow

Question 2

Purpose of reservoirs - water supply

Answer 2

taking care of fluctuation in water demand (reducing water when demand is less and releasing water when high)

Question 3

Purpose of reservoirs - flood control

Answer 3

store flood water and reduce peak

Question 4

Purpose of reservoirs - power generation

Answer 4

make use of high water head

Question 5

Water supply - environment protection

Answer 5

as water is taken from natural rivers, compensation flow should be discharged to maintain the ecology and environment of the river

Question 6

Types of surface sources - direct supply storage

Answer 6

impounding of a gravity inflow and the piping of most flow directly into supply

Question 7

Types of surface sources - pumped storage

Answer 7

inflow mainly taken from pumping

Question 8

Types of surface sources - regulating reservoirs

Answer 8

primarily impound water for later release when flow downstream (abstraction point becomes too low)

Question 9

How are mass curves related to a reservoirs?

Answer 9

plotting mass curves of both natural river inflow and water demand means the periods when inflow water is higher or lower can be easily identifiable

Question 10

Limitations of mass curve method

Answer 10

1) different mass curves may be obtained when different historical flow records are used. ‘typical year/s’ need to be chosen to represent the most likely scenario
2) it can not tell the probability if the reservoir would fail even with the same level of the water demand, due to the variability of natural river flows

Question 11

Risk analysis

Answer 11

1) ‘reservoir empty’ due to severe droughts
- we require to perform despite the event being less severe than the threshold event