Flooding at the Port of Port Townsend: Marina ramps should not have negative slope
During the afternoon of December 20th, 2018, my hometown of Port Townsend, WA experienced an extreme tidal event known as a “king tide”. While this event, an abnormally high tide of +11.0ft, caused no loss of life and only minor flooding and property damage, it served as a preview of Port Townsend’s potentially waterlogged future.
Port Townsend sits on the Quimper Peninsula, a small promontory protruding into the Puget Sound off of the Northeast corner of the much larger Olympic Peninsula. While most of Port Townsend’s residential areas are located at least a few hundred feet above sea level, the town’s historic downtown, full of thriving small businesses, as well as the Port of Port Townsend, one of the county’s largest employers, sit just a few feet from the high tide line. Though this waterfront location provides much of Port Townsend’s charm, it leaves much of the town’s economy vulnerable to flooding from higher-than-usual tidal events.
 |
Port Townsend, shown in the context of the greater Puget Sound
|
King tides, such as the one that struck Port Townsend on 12/20/18, are caused by astronomical events that exacerbate the effect of the moon’s gravity on tidal motion. These events can be the alignment of the sun or other celestial bodies with the moon, or they can be seasonal changes in tidal patterns due to the orbit of the Earth and moon. The 12/20/18 event is part of a greater pattern of “winter king tides” that occur in late December/early January when Earth is at the point in its orbit where it is closest to the sun. Winter king tides in Port Townsend are typically between 9 and 10 feet, so even within this annual pattern the 12/20/18 event was an anomaly.
Port Townsend's Northwest Maritime Center at a normal high tide vs during the 12/20/18 king tide.
So what can we learn from these extreme high tide events? Many believe these tides may provide a glimpse into the future for coastal communities such as Port Townsend, where these events that presently only occur a few times a year may become the new norm due to sea level rise in the coming decades. What does this mean for the future of Port Townsend’s downtown business district and maritime industry? Anthropogenic climate change has already “locked in” a degree of future sea level rise regardless of whether we are able to lower global emissions, so communities like Port Townsend will be forced to adapt and overcome. Let today’s extreme tides serve as a warning for tomorrow - the City of Port Townsend must help facilitate development for a future where today’s waterfront may be underwater, or risk the collapse of the many of the community’s economic engines.
 |
| Port Townsend's susceptibility to flooding based on models of future sea levels.
References:
|
to anyone reading this: I am not sure what is good with the formatting at the moment, for some reason my first two paragraphs of text appear in my editing window but not in the published version. If u know how I can fix this please let me know.
ReplyDeleteIs the local area doing anything to prepare for this slowly worsening geohazard?
ReplyDelete