A Decision Framework for Managing the Spirit Lake and Toutle River System at Mount St. Helens (2018) / Chapter Skim
Currently Skimming:
8 Decision Consequences and Trade-Offs
8 Decision Consequences and Trade-Offs
Pages 247-272
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 247... ...
The chapter concludes with a brief discussion of PrOACT-like (Problem, Objectives, Alternatives, Consequences, Trade-offs) processes as compared to existing agency processes.
|
From page 248... ...
There may be a wide range of beliefs concerning a number of key underlying physical processes such as • limiting factors for fish abundance and o the ability of fish to migrate past the sediment retention struc ture (SRS) , o the ability of fish to pass through the sediment field above the SRS, and o the impacts of dredging on aquatic habitat and fish migration; • limiting factors for increased dredging capabilities, including o where spoils can be put, o acceptance of local residents to the placement of spoils, o impact of dredging on listed species migration, and o the ability to secure environmental permits in a timely manner; • long-term performance of the tunnel, including o seismic withstand, and o the ability of tunnel to perform given the underlying geologic composition and dynamism of the surrounding rock; • operational risk arising from tunnel repair closures; • volume of material transfer from debris field, including whether the long-term trend of sediment migration is constant or declining; • susceptibility of an open channel solution to downcutting from erosion; • calculations of a Probable Maximum Flood (PMF)
|
From page 249... ...
. Influence diagrams, developed through discussion with decision participants, can clarify cause-and-effect relationships among the issues being considered.
|
From page 250... ...
A standard approach for capturing uncertainty (Morgan and Henrion, 1990) involves • Modeling consequences using midpoint or best estimates to start; • Identifying parameters (or hypotheses)
|
From page 251... ...
Yet this information is critical to developing an understanding of how the different alternatives perform in preventing a catastrophic breakout. It is up to technical specialists working with the decision participants to finish this task.
|
From page 252... ...
The process of developing a consequence table helps the group create legitimacy of subsequent decisions among themselves and with a broad group of interested and affected parties. Box 8.1 provides examples of past communication of comparison of management alternatives for the Spirit Lake and Toutle River region.
|
From page 253... ...
(An interactive spreadsheet allows this basis of comparison to be changed during discussion.) This interactive visual tool is an excellent aid for exploring how management alternatives align with the decision objectives of the participants.
|
From page 254... ...
TABLE 8.1 An Example Consequence Table for Comparing Optionsa 254 Performance Objective Measure Units Dir Alt 1 Alt 2 Alt 3 Alt 4 Alt 5 Alt 8 Minimize Flooding Flood @Lower Bridge River Frequency # days/yr Lb 1 1 0 0 0 0 Flood @Seton Reservoir Frequency # days/yr L 6 6 6 6 6 6 Maximize Fish Abundance @Carpenter Reservoir Fish Index 1-100 Hc 69 70 41 41 29 29 @Downton Reservoir Fish Index 1-100 H 42 71 48 69 65 69 @Lower Bridge River Fish Index 1-100 H 100 100 100 90 25 10 @Seton Reservoir Fish Index 1-100 H 66 66 66 66 33 10 Maximize Water Quality Water Suspended @Seton Reservoir Solids Tonnes/yr L 94 89 77 84 108 78
|
From page 255... ...
Maximize Vegetated Area @Downton Reservoir Weighted Area Hectares H 223 231 322 313 295 300 @Carpenter Reservoir Weighted Area Hectares H 759 522 758 520 602 600 Maximize Power Benefits Maximize Power Levelized Revenues Revenues $M/yr H 141 145 146 149 144 145 a Blue represents the point of comparison; red indicates alternative measures significantly worse than blue; green indicates alternative measures significantly better; no color indicates no significant difference. b L indicates lower numbers are preferable.
|
From page 256... ...
explains alternative strategies for managing Spirit Lake water levels and also presents alternatives using extended prose descriptions of good and bad features, again making it difficult to apply the decision objective metrics across alternatives. (Note that Table 7.1 was not part of the 2016 report but was presented to the committee during an open session.)
|
From page 257... ...
This discussion can improve understanding about why different parties hold different views on the alternatives; about how susceptible the decision objective in question is to the occasionally poor outcome; and, perhaps, about how to identify ways to modify the otherwise preferred alternative to mitigate these rare occurrences. TABLE 8.2 A Hypothetical Example of Higher Cost Versus Higher Certainty Trade-off Alternative Alternative Objective Sub-Objective Metric 1 2 Maximize Maximize expected usable Haa (P50)
|
From page 258... ...
Whether or not this incremental level of effort is warranted depends on the situation. Helping decision participants collaboratively explore multiple alternatives when there is significant uncertainty across multiple objectives is inherently challenging.
|
From page 259... ...
For example, asking a participant in the Bridge River water management process highlighted in BOX 8.2 Examples of Trade-Offs That Might Be Considered for Management of the Spirit Lake and Toutle River System Based on input received by the committee during public session meetings, some antic ipated trade-offs might be • Downstream sedimentation versus the "naturalness" of the drainage system; • Cost versus catastrophic flood risk, particularly if the decision process includes consideration of multiple and redundant engineering solutions to managing Spirit Lake water levels; • Sediment retention versus fish recovery; • Sediment retention versus wildlife recovery; • Fish populations downstream of the SRS versus fish populations upstream of the SRS (but only if participants see this as an important trade-off instead of seeing the abundance of the aggregate fish population being of primary importance) ; • Short- versus long-term actions and consequences, particularly if it turns out that the system is likely to "reset" itself every few decades (e.g., through seismic or volcanic activity)
|
From page 260... ...
The trade-off step is about exploring that decision space; looking for insights into how values are affected by the way in which the system reacts to changes; and looking for mutually advantageous solutions or, at least, solutions where important gains for some decision participants can be found without too much sacrifice of the interests of other participants. Developing consequence tables was discussed in the previous sections.
|
From page 261... ...
may be an indication of whether a particular metric can be ignored in decision making. Note the important process implications here: a decision objective and metric were put into the consequence table because one or more of the decision participants believed they were important factors when comparing alternatives.
|
From page 262... ...
There is also an important communication element here. If this issue was important to the decision participants, then it is likely that it will be important to those outside the process as well.
|
From page 263... ...
First, monetization of consequences can be controversial, and doing so before mutual trust has developed may undermine the legitimacy of the decision process. Second, leaving consequences in their natural units until consideration of trade-offs increases the opportunity to align understanding of consequences and participants' decision objectives.
|
From page 264... ...
. While the swing weighting approach is built on and consistent with the theory of consumer choice as found in any microeconomics textbook, it is not an optimization process that generates the best answer based on objectively defined decision weights.
|
From page 265... ...
As with all these tools, it is necessary to maintain communications with all decision participants to explicitly test whether the extra process burden is worth the resulting insights it could reveal. It is important for participants to know that these valuation tools do not supplant decision making; rather, they help participants gain additional insights into their decision objectives that otherwise might be obscured by the multiple-objective decision making in a complex management system.
|
From page 266... ...
TABLE 8.3 Consequences, Swing Weighted from Worst to Best 266 Swing Weighting Sub-Objective-Level Swing Weighting Performance Objective Sub-Objective Measure Units Dir Worst Best Rank Weight Minimize Flooding @Lower Bridge River Flood frequency #days/yr L 1 0 @Seton Reservoir Flood frequency #days/yr L 6 6 Maximize Fish Abundance @Carpenter Reservoir Fish index 1-100 H 29 70 @Downton Reservoir Fish index 1-100 H 42 71 @Lower Bridge River Fish index 1-100 H 10 100 @Seton Reservoir Fish index 1-100 H 10 66
|
From page 267... ...
Maximize Water Quality Water suspended @Seton Reservoir solids Tonnes/yr L 108 77 Maximize Vegetated Area @Downton Reservoir Weighted area Hectares H 223 322 @Carpenter Reservoir Weighted area Hectares H 520 759 Maximize Power Benefits Levelized Maximize Power Revenues Revenues $M/yr H 141 149 SOURCE: Gregory et al., 2012.
|
From page 268... ...
o Structure longer-term data gathering? • If there are complex trade-offs that include multiple options and multiple conflicting decision objectives, has a structured approach such as swing weighting been used to help interested and affected parties construct their values around these complex and novel trade-offs?
|
From page 269... ...
In fact, these formally stated reservations may form the basis of discussion regarding monitoring, adaptive management triggers, and the conditions of future reviews. COMPATIBILITY OF A PROACT-LIKE PROCESS WITH AGENCY PROCESSES Determining whether the decision framework recommended in this report is better than another framework, or no framework at all, requires that the framework be decomposed into its overarching elements of organized participation and the integration of science.
|
From page 270... ...
Whether a process similar to PrOACT is better than some alternative for structuring the analytic content of public participation is difficult to assess. The decision process described in this report draws on real-world experience as well as current understanding of how people make decisions in complex and unfamiliar situations.
|
From page 271... ...
Decision Consequences and Trade-Offs There is a broad alignment between the steps laid out in a PrOACT-like process, those in a USACE planning process, and a document prepared to comply with the National Environmental Policy Act, with perhaps a bit more granularity given by the five steps of the PrOACT framework. Given these similarities, following the recommended decision framework will not preclude also satisfying individual agency planning processes.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.