Discussion: View Thread

  • 1.  Are we properly considering sea level rise effects in our work?

    Posted 04-20-2024 06:27 PM

    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?



    ------------------------------
    William McAnally Ph.D., P.E., BC.CE, BC.NE, F.ASCE
    ENGINEER
    Columbus MS
    ------------------------------


  • 2.  RE: Are we properly considering sea level rise effects in our work?

    Posted 04-22-2024 11:38 PM

    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.



    ------------------------------
    Mitch Winkler P.E.(inactive), M.ASCE
    Houston, TX
    ------------------------------



  • 3.  RE: Are we properly considering sea level rise effects in our work?

    Posted 04-25-2024 12:32 PM

    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.



    ------------------------------
    James Bush P.G., RG, A.M.ASCE
    President and CEO
    Los Fresnos TX
    ------------------------------



  • 4.  RE: Are we properly considering sea level rise effects in our work?

    Posted 04-25-2024 12:31 PM

    There are many general and regional guidelines – authored by different federal and state agencies, and others. But, blanket adoption of such guidelines – may either prove too conservative or inadequate. This is because the hydraulics of a certain project location may not often align with what are suggested in the guidelines. Moreover, such guidelines come with disclaimer lines – implying that it is the responsibility of the engineer to defend why certain values are adopted and applied. Therefore, the relevance of highlighting limitations, assumptions and constraints in project documents becomes important. As a note, Sea Level Rise (SLR) and associated issues have been discussed – in at least 5 different threads before. Further:

    • Science of SLR and effects are still evolving and fluid as new information and assessments are pouring in. Therefore due diligence is imperative – this is more so for large projects than smaller ones. I have tried to touch upon some of them – in Sea Level Rise Science (among others, highlighted uncertainty in SLR predictions based on USACE compilation); Sea Level Rise Consequences (among others, highlighted the consequences of SLR on coastal water level and engineering implications); Standards and other articles, e.g. Storm Surge (among others, highlighted high storm surge effects due to SLR induced water level changes).

    • In addition – here are some others: FHWA-HIF-22-051; and on hydraulics issues and modeling FHWA-HIF-19-059. There are also USACE SLR Tracker and User Guide Series and others that one take advantage of. A Boston Harbor magazine article highlights some of their local issues on SLR effects from all different perspectives.

    Dilip

    -------

    Dr. Dilip K Barua, Ph.D

    Website Links and Profile




  • 5.  RE: Are we properly considering sea level rise effects in our work?

    Posted 04-25-2024 11:48 PM

    One of my firm's clients is a municipal water utility situated between two rivers, and they have begun trying to incorporate climate change considerations into their future planning and design efforts.  Most of it is related to the rainfall side of climate change, but a certain portion is related to sea level rise as well. 



    ------------------------------
    Christopher Seigel P.E., M.ASCE
    Civil Engineer
    ------------------------------



  • 6.  RE: Are we properly considering sea level rise effects in our work?

    Posted 04-25-2024 11:49 PM

    According to a 2023 study by HGA (a design firm) and the University of Minnesota (see https://hga.com/climate-forward/), most A&E firms are not taking future sea level rise, or for that matter, the other aspects of climate change adaptation into account in their projects. Few firms are using climate projections to make design decisions.  The barriers include lack of client requests; lack of standards and codes; data resolution needs; format, content, and cost; trust of the data; and a need for internal expertise to use the data.

    But, there is also a risk of not considering climate change in the design of civil infrastructure.  Relying on historical experience on making design decisions even when credible authorities like the US Fifth National Climate Assessment (https://nca2023.globalchange.gov/) state that future climate conditions will no longer resemble the past may be considered as falling below the standard of care.

    Here comes the self-serving part.  To help students, engineers and others working in the built environment to deal with a changing climate, I wrote a book called "The Great Civil Engineering Overhaul" scheduled to be published by ASCE in early June 2024.  In it, I explain climate change and its effects on the built environment.  I also offer several methodologies for planning, designing and delivering projects that are climate resilient, adaptable and contribute to conditions of sustainability.



    ------------------------------
    [Bill] [Wallace] [ENV-SP, F.ASCE]
    [Wilsonville] [Oregon]
    ------------------------------



  • 7.  RE: Are we properly considering sea level rise effects in our work?

    Posted 05-13-2024 10:08 AM

    Thanks, Mr. Wallace. I look forward to seeing your book.

    Bill Mc



    ------------------------------
    William McAnally Ph.D., P.E., BC.CE, BC.NE, F.ASCE
    ENGINEER
    Columbus MS
    ------------------------------



  • 8.  RE: Are we properly considering sea level rise effects in our work?

    Posted 05-13-2024 10:08 AM

    Thanks for the thoughtful comments. 

    Dilip mentions the NOAA-COE SLR online calculator (https://climate.sec.usace.army.mil/slat/). It is regularly updated and is site-specific -- using local water level records in conjunction with standard SLR models to project low, intermediate, and high rates of sea level change. I consider that to be the authoritative source for SLR projections. Some (many?) design and evaluation documents CITE the calculator but then do little with the information it provides.

    Steps such as those mentioned by the valuable comments given here should be part of the standard engineering toolbox. Assigning risk -- probable costs and benefits on the range of predicted sea levels -- provides designers and decision makers with needed information.

    Bill Mc



    ------------------------------
    William McAnally Ph.D., P.E., BC.CE, BC.NE, F.ASCE
    ENGINEER
    Columbus MS
    ------------------------------



  • 9.  RE: Are we properly considering sea level rise effects in our work?

    Posted 05-14-2024 10:11 AM

    Before about 20 years, there was no design consideration for climate change, specifically for rising sea levels due to global warming. Based on sea level measurements, there was clear evidence that the mean sea level increases based on which several RFPs requested to consider the sea level rise in the design of coastal structures and flooding. Since there are many uncertainties in the projected models where several emission scenarios produce different sea level rise. Designers choose the worst-case emission scenario when determining the design water level. This would, in turn, result in a relatively pricy solution.

    *******************************

    Kind Regards, 

    Ahmed Sayed Mohamed, PhD, BC.CE, CEng, M. ASCE, FRINA

    Senior Coastal Engineer

    Geotechnical and Heavy Civil Eng. Dep.

    Smart Village, Street 26, Building 10

    P.O. Box: 129, Giza 12577, Egypt

    Tel:  +202 35318000 (Ext: 1153)

    dar.com

    ***************



    ------------------------------
    Ahmed Ahmed Ph.D., C.Eng, BC.CE, M.ASCE
    Senior Coastal Engineer
    Dar Al Handasah (Shair and Partners)
    Giza
    ------------------------------



  • 10.  RE: Are we properly considering sea level rise effects in our work?

    Posted 2 days ago

    Ahmed, following our earlier discussions on this – here are something more I like to add.

    The short answer is Sea Level Rise (SLR) is an important element of planning and design considerations in most, if not all of contemporaneous Coastal CE works.

    • The question is whether this factor gets 'proper' consideration. Maybe it does, maybe it doesn't. The ambiguity is due to the uncertainty in scientific observations and future projections.

    • There was a different but relevant discussion in the thread: Will . . . Civil Engineering More Attractive? - where climate-related civil engineering standards came into limelight. This is another reason why a question like 'proper' can hardly be answered in definitive terms.

    • There have been at least two other threads in the past – that maybe of some help to clarify some of our thoughts. They are: Knocking of Rising Seas in Higher Frequencies and Sea Level Rise Low Lying Airports.

    Dilip

    -------

    Dr. Dilip K Barua, Ph.D

    Website Links and Profile