I think Mr. Winkler is heading in the right direction, but this question is far more robust that probably any of us accurately recognize. First off, IPCC itself really doesn't know which models are "truly" correct. Second, site specific effects of all the storm parameters (storm surge, wave set up, combination of drainage flooding's geographically simultaneous impact with gross tidal rise, etc. etc.) also have to take into account the land topography - which changes with sea level rise and future construction… FEMA modeling for land flood risk classification frequently does not take this into account, and their GIS alignment with properties is frequently in error. The variables quickly become overwhelming when we have to take into account the challengingly robust parameter of being "cost effective" particularly in the more robust "cost-benefit", hence my frustration is almost to the point of disgust. Furthermore, in this context, just the definition of "benefit" is difficult, i.e. while one choice may help overcome one problem, it may contribute to another. In this area we have recently discovered that flood drainage discharge of two communities ultimately drains to the same area (considerably outside our purview), to the extent that allowing one community to drain more aggressively backs up water to the other - helping one, harms the other. Perhaps the notion of transferring portions of the "responsibility of the decision/choice" to the client would be satisfactory, more likely barely satisfactory. Being able to put probabilities on certain parts of the impact of a sea level rise scenario, or at least ranking them, would allow the client to choose thereby sharing the burden of "cost effective/cost benefit". It also would give a client a better understanding of what we now "guess" is the most likely future, allowing them to participate in the risk/benefit decisions…providing, of course, that the client fully understands the uncertainty of "most likely" future.
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James Bush P.G., RG, A.M.ASCE
President and CEO
Los Fresnos TX
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Original Message:
Sent: 04-22-2024 04:10 PM
From: Mitchell Winkler
Subject: Are we properly considering sea level rise effects in our work?
A big challenge with sea level rise is what model to believe and how much stock to put in ordinances or design guidelines. They are probably wrong as the uncertainties with the rise of sea level are too significant, and then there is what we do not know. I think designing for sea level rise is a situation that demands a complementary approach to safety-critical systems. For safety-critical systems, one designs to As Low As Reasonablly Practicable (ALARP). For a safety risk to be ALARP, it must be possible to demonstrate that the cost involved in reducing the risk further would be grossly disproportionate to the benefit gained. One should consider designing as high as reasonably practicable for sea level rise. This incremental mitigation would be on top of any minimum set by local ordinances or design guidelines. This approach has a cost, but it is a tradeoff that responsible owners/clients should heed.
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Mitch Winkler P.E.(inactive), M.ASCE
Houston, TX
Original Message:
Sent: 04-20-2024 10:48 AM
From: William McAnally
Subject: Are we properly considering sea level rise effects in our work?
A recent ASCE Civil Engineering Source article by Scott Douglass asked, "What future sea-level rise should we design for today?" It's an important question for designers, planners, and those who write and review environmental assessments in most areas.
Sea level issues arise in obvious ways such as tidal flooding, increased wave penetration, and submergence of structures, but also in less obvious ways such as decreased land drainage slope, increased salinity intrusion, and contamination of groundwater supplies.
Are we properly considering sea level rise effects in our work? What should we be doing differently?
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William McAnally Ph.D., P.E., BC.CE, BC.NE, F.ASCE
ENGINEER
Columbus MS
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