390
17 Environmental Flow Definition and Management: A Case Study …
Proposed 2020 reservoir operating rules changed?
No
Yes
No
Yes
Environmental flow rules included?
S3
S9
S7
S8
S1
S2
S6
S5
S1
S11
S4
Fig. 17.7 Diagrammatic representation of modeled scenarios. Source WET (2007). Permission
granted by WET project subject to proper citation
17.3.5 Analyses of Modeling Results
17.3.5.1 Scenario 2: Current Proposed Arrangements for year 2020
Scenario 2 models expected flows and reliabilities based on the currently planned
supply and operational arrangements for 2020.
(1) Implications for reliability of supply
The local water supply from Zhu Creek for urban/industrial is provided at a daily
reliability of over 97%. Annual reliability for irrigation from Zhu Creek is 100%.
From Changtan Reservoir, urban industrial users are suppled at an annual reliability
of 96% and a daily reliability of 82%. Irrigation supplied from Changtan Reservoir
has an annual reliability of 69%.
Based on the model results, reliability of supply for all purposes from Changtan
Reservoir is likely to be below an acceptable level for the currently proposed
arrangements.
(2) Implications for environmental flows
Table 17.13 provides an overview on the impact of the proposed 2020 development of
most of the environmentally important flows within Reaches 1, 2, and 3. The greatest
impacts are in Reach 1 immediately downstream of Zhuxi Reservoir. Baseflows at the
required level are almost non-existent (Fig. 17.8), and the number of environmentally
important pulses (both low and high) is reduced to 5% or less of their natural number.
17 Environmental Flow Definition and Management: A Case Study …
Proposed 2020 reservoir operating rules changed?
No
Yes
No
Yes
Environmental flow rules included?
S3
S9
S7
S8
S1
S2
S6
S5
S1
S11
S4
Fig. 17.7 Diagrammatic representation of modeled scenarios. Source WET (2007). Permission
granted by WET project subject to proper citation
17.3.5 Analyses of Modeling Results
17.3.5.1 Scenario 2: Current Proposed Arrangements for year 2020
Scenario 2 models expected flows and reliabilities based on the currently planned
supply and operational arrangements for 2020.
(1) Implications for reliability of supply
The local water supply from Zhu Creek for urban/industrial is provided at a daily
reliability of over 97%. Annual reliability for irrigation from Zhu Creek is 100%.
From Changtan Reservoir, urban industrial users are suppled at an annual reliability
of 96% and a daily reliability of 82%. Irrigation supplied from Changtan Reservoir
has an annual reliability of 69%.
Based on the model results, reliability of supply for all purposes from Changtan
Reservoir is likely to be below an acceptable level for the currently proposed
arrangements.
(2) Implications for environmental flows
Table 17.13 provides an overview on the impact of the proposed 2020 development of
most of the environmentally important flows within Reaches 1, 2, and 3. The greatest
impacts are in Reach 1 immediately downstream of Zhuxi Reservoir. Baseflows at the
required level are almost non-existent (Fig. 17.8), and the number of environmentally
important pulses (both low and high) is reduced to 5% or less of their natural number.