[GWSG] NC floods vs. tide gauges; Miami flood study; ground water in Hawaii; saline ground water; editorial nag

[Tilley, Al]

1. A study by two universities in North Carolina found that flooding in coastal regions was not well indicated by official figures, based on tide gauges and the NOAA and National Weather Service flood thresholds which miss rises in ground water, runoff from rain, and other sources. The government sources may also ignore effective drainage measures. “For example, when you subtract floods associated with extreme storms, we recorded flooding on 122 days in Sea Level (NC). But if you looked at the data from the closest tidal gauge, the NWS threshold inferred that there were 31 days of flooding. And the HTF threshold inferred only nine days of flooding.” In contrast, flooding in Carolina Beach actually occurred on 65 days, but was indicated on 120 days by the closest tidal gauge.  https://www.sciencedaily.com/releases/2025/06/250602155338.htm
Coastal Review supplies further information on the study. https://coastalreview.org/2025/06/coastal-areas-flood-more-frequently-than-thought-study/   Coastal communities may need more detailed planning for climate adaptation, on another schedule than they had thought.
2. The Miami Herald reports a study of the combined effects of sea level rise, rainfall, and rising ground water levels in Broward County. The study should be an eye-opener for coastal communities generally. https://www.miamiherald.com/news/local/environment/climate-change/article307805065.html
3. We have known about the crucial role of ground water in coastal flooding for over ten years following a study in Hawaii, but it has seldom been attended to in vulnerability studies.  https://www.higp.hawaii.edu/hggrc/groundwater-flooding-due-to-rising-sea-levels/
4. As sea level rise translates to a rise in ground water levels, salinity profiles also change. The corrosive effect of newly saline water in infrastructure is a major threat to coastal communities. The damage “can occur decades before SLR-induced surface inundation.” https://pubmed.ncbi.nlm.nih.gov/37540890/
5. If you have not been reading about the insect apocalypse or the crossing of the planetary boundary for ocean acidification, you should Google the topics. (I try in this list to address issues new to most of us—if ground water concerns are old hat to you, I have wasted your time.) Our Trumped-up troubles in the US should not distract us from the real issues which face us, however they are complicated by political exigencies and the attack on science and education in general. Bugs, phytoplankton shells, and ground water need our attention. We must support attempts to deal with the climate even as we work to preserve our democracy and to defend vulnerable minority populations.


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