|
7.1
Status Quo 7.2
Imminent Supply 7.3
Scenario Evaluation
7. Scenarios
The CRYSTAL model may be utilized to investigate the model in its present
status, as well as future changes to the system and possible system alterations.
The following portion of this guide discusses two scenarios. The first scenario
allows the user to evaluate the system in its current condition. The imminent
scenario depicts the system after future options have been implemented including
instream flow requirements, increased reservoir storage, and an intertie between
Tacoma and Seattle.
Demands
The goal of these and all other water supply systems is to provide a safe and
reliable supply. This goal must be met in the present and be continued into the
future. In order to model the system in a useful manner, the user must be able
to evaluate the system's future effectiveness. Using available demand forecasts
to evaluate future loads upon the regional water supply may provide this look
into the future. Although demand projections are frequently proved incorrect,
they remain a useful tool for evaluating current and imminent alterations to the
supply system. Model sensitivity to changing demands upon the system will
provide information about the actual system's behavior.
CRYSTAL provides demand options that may be incorporated into a model
simulation, as seen in Figure 7.1. More details about the individual demand
projections may be found within the model description.
|
Year of Investigation |
This field determines the demand load on the water supply used in the
model simulation. The Year of Investigation may be input only in the
Regional Control Panel. The user inputs a Year of Investigation ranging
between 1994 and 2040.
Everett demand projections were obtained in 1999. Forecasts were
provided through the year 2020 and then extrapolated to include the year
2040.
The demand projections for Seattle were obtained from Seattle Public
Utilities in 1997. These projections were extrapolated from the year 2020
to include the year 2040.
Tacoma demand projections were obtained from the 1998 Draft of the
Comprehensive Water Plan Update. |
|
Tacoma Total Demand Projection |
This option allows user to choose one of two possible Tacoma demand
projections. Tacoma Public Utilities has issued projections which
incorporate demands covering a small (low demand) or large (high demand)
service area. |
|
Seattle Variable Demand |
Selecting this option initiates a variation of base demand that
responds to temperature and precipitation data (i.e. more climate
dependent demand function).
The conventional (default) option determines demand using a seasonal
factor. |
|
Everett % Increase Demands |
This sliding bar allows the model user to increase Everett demands
between 0 and 40%. |
|
Seattle 1% Conservation per Year |
Selecting this option initiates a one percent per year demand reduction
each year for 10 years. Seattle Public Utilities and their purveyors have
agreed to begin this initiative during the spring of 2000. This option is
a selection included in both scenarios. |
|
Tacoma Industry Water Conservation |
This option reduces the Tacoma projected average demand by implementing
industrial water conservation. Tacoma Public Utilities estimate that
industrial mills could conserve 9.4 mgd. |
|
Tacoma Industry Water Reuse |
This option reduces the Tacoma projected average demand by implementing
industrial water reuse. Tacoma Public Utilities estimate that industrial
mills could reduce demands by 17.2 mgd if they recovered and reused
process water. |
Figure 7.1 Regional Water Demand
Forecasts
Table 7.1 provides a brief summary of the scenarios presented earlier. A
check indicates that the option is activated when running the given scenario.
Table 7.2 Summary of Scenarios
|
Option |
Status Quo Scenario |
Imminent Scenario |
|
HAH Expansion/Second Supply Project |
|
ü |
|
Green River HCP Phase I |
|
ü |
|
Cedar River HCP |
|
ü |
|
Seattle |
|
|
|
1% Conservation per Year |
ü |
ü |
|
Implement Curtailments |
|
|
|
Begin Pumping |
ü |
ü |
|
Highline Well Capacity |
10 mgd |
10 mgd |
|
Pump Cedar Dead Storage |
|
|
|
Pump to 30' Drawdown |
|
|
|
Tolt Relies on Cedar |
ü |
ü |
|
Tolt Pipeline II |
|
ü |
|
No Tolt Treatment Facility |
ü |
|
|
Elevation at 1660 |
|
|
|
Elevation at 1690 |
|
|
|
Elevation at 1710 |
|
ü |
|
Tacoma |
|
|
|
Section 1135 Storage |
ü |
|
|
Conserve/Curtail |
|
|
|
Expand Tideflat Groundwater |
|
ü |
|
Chambers Creek - 5.2 mgd |
|
|
|
Chambers Creek - 9.3 mgd |
|
|
|
Industrial Water Conservation |
|
|
|
Industrial Water Reuse |
|
|
|
Corps Basline Flow Targets |
ü |
|
|
Normal Ecology Flow Targets |
|
|
|
Critical Ecology Flow Targets |
|
|
|
Muckleshoot Baseflow Targets |
|
|
Table
of Contents
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