4 ms·

This was a 1000 year flood. They probably did plan for 100/500 year floods in choosing the location of these facilities, but you can't reasonably build every cr

This was a 1000 year flood. They probably did plan for 100/500 year floods in choosing the location of these facilities, but you can't reasonably build every critical structure outside 1000-year flood plains.

dredmorbius 2y ago
A 1000 year flood, perhaps, based on 2008-era flood risk maps. The facility was built within a 500 year (0.2% annual flood risk) basin. It's on a flat escarpment surrounded on three sides by the Nolichuky River, in a region characterised by steep terrain and narrow river valleys. The sort of terrain in which if, or rather, when a major tropical storm (or its remnants) moves through will be subject to high levels of flooding. I'm focusing on the Unicoi hospital largely as I'd heard of the heliocopter rescues from it in earlier broadcast news reports, but nothing of its specific situation, when it was planned and built (within the past decade), or the fact that what should have been a major feature of rescue and recovery capabilities was in fact a rescue and recovery target, both diverting resources from elsewhere and eliminating a local point from which aid could have been rendered and coordinated. A much broader point is that this is all but certainly not an exceptional case, and that there are likely similar facilities, or other high-risk activities (e.g., nuclear fuel servicing, a half mile upriver) which are similarly at risk, in Tennessee, surrounding states, and elsewhere in and outside the US, and that a comprehensive review and remediation effort based on identifying risks, updating flood maps, and mitigating or moving both first-responder and other high-risk facilities outside flood or other risk areas be addressed. Climate is changing rapidly, and one characteristic I'm observing are large, moisture-laden, slow-moving storms (Florence (2018), Harvey (2017), and of course Katrina (2005)) which dump immense amounts of rain over side areas. Harvey in particular dumped over 1000mm (40in) of rain over Houston and surrounding areas (peak: 1,539 mm / 60in),[1] which at one tonne per square metre of land actually caused the land in the region to measurably lower, as I recall. (I'm not finding a citation for this, though I'm reasonably certain of my memory. Total rainfall exceeded 16 trillion gallons, or ~63 billion tonnes: <https://apnews.com/article/science-floods-storms-hurricanes-hurricane-harvey-c536ba2a2c074ad3919ec0537966725c https://apnews.com/article/science-floods-storms-hurricanes-...>.) There are numerous communities which likely suffered similar impacts as Erwin, TN, and far more which are at risk of future extreme inundation events. And NOAA/NHC are presently five tropical storms in the Atlantic basin, another two in the Eastern Pacific. <https://www.nhc.noaa.gov/?atlc https://www.nhc.noaa.gov/?atlc> <https://www.nhc.noaa.gov/?epac https://www.nhc.noaa.gov/?epac> Longer-range forecasts (through about 5 October) show potential for more Gulf-originating storms as well. We're hardly through this season yet. Rumours are that there will be other seasons afterward. ________________________________ Notes: 1. <https://en.wikipedia.org/wiki/Hurricane_Harvey#Texas_2 https://en.wikipedia.org/wiki/Hurricane_Harvey#Texas_2>

dredmorbius 2y ago

A 1000 year flood, perhaps, based on 2008-era flood risk maps. The facility was built within a 500 year (0.2% annual flood risk) basin. It's on a flat escarpment surrounded on three sides by the Nolichuky River, in a region characterised by steep terrain and narrow river valleys. The sort of terrain in which if, or rather, when a major tropical storm (or its remnants) moves through will be subject to high levels of flooding. I'm focusing on the Unicoi hospital largely as I'd heard of the heliocopter rescues from it in earlier broadcast news reports, but nothing of its specific situation, when it was planned and built (within the past decade), or the fact that what should have been a major feature of rescue and recovery capabilities was in fact a rescue and recovery target, both diverting resources from elsewhere and eliminating a local point from which aid could have been rendered and coordinated. A much broader point is that this is all but certainly not an exceptional case, and that there are likely similar facilities, or other high-risk activities (e.g., nuclear fuel servicing, a half mile upriver) which are similarly at risk, in Tennessee, surrounding states, and elsewhere in and outside the US, and that a comprehensive review and remediation effort based on identifying risks, updating flood maps, and mitigating or moving both first-responder and other high-risk facilities outside flood or other risk areas be addressed. Climate is changing rapidly, and one characteristic I'm observing are large, moisture-laden, slow-moving storms (Florence (2018), Harvey (2017), and of course Katrina (2005)) which dump immense amounts of rain over side areas. Harvey in particular dumped over 1000mm (40in) of rain over Houston and surrounding areas (peak: 1,539 mm / 60in),[1] which at one tonne per square metre of land actually caused the land in the region to measurably lower, as I recall. (I'm not finding a citation for this, though I'm reasonably certain of my memory. Total rainfall exceeded 16 trillion gallons, or ~63 billion tonnes: <https://apnews.com/article/science-floods-storms-hurricanes-hurricane-harvey-c536ba2a2c074ad3919ec0537966725c https://apnews.com/article/science-floods-storms-hurricanes-...>.) There are numerous communities which likely suffered similar impacts as Erwin, TN, and far more which are at risk of future extreme inundation events. And NOAA/NHC are presently five tropical storms in the Atlantic basin, another two in the Eastern Pacific. <https://www.nhc.noaa.gov/?atlc https://www.nhc.noaa.gov/?atlc> <https://www.nhc.noaa.gov/?epac https://www.nhc.noaa.gov/?epac> Longer-range forecasts (through about 5 October) show potential for more Gulf-originating storms as well. We're hardly through this season yet. Rumours are that there will be other seasons afterward. ________________________________ Notes: 1. <https://en.wikipedia.org/wiki/Hurricane_Harvey#Texas_2 https://en.wikipedia.org/wiki/Hurricane_Harvey#Texas_2>