{"id":5709,"date":"2016-03-01T13:10:00","date_gmt":"2016-03-01T18:10:00","guid":{"rendered":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/?page_id=5709"},"modified":"2024-08-15T16:23:20","modified_gmt":"2024-08-15T20:23:20","slug":"currents-data-surge-better-storm-records-will-improve-predictions","status":"publish","type":"post","link":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/currents-data-surge-better-storm-records-will-improve-predictions\/","title":{"rendered":"CURRENTS: Data Surge: Better Storm Records Will Improve Predictions"},"content":{"rendered":"\n\n\n\n\n

The National Sea Grant College Program<\/a> is celebrating its 50th anniversary through March 2017. The monthly theme for May 2016 is Community Resilience. To recognize North Carolina Sea Grant\u2019s long-time role in resiliency efforts, Spencer Rogers<\/a> offers this essay. Rogers has been North Carolina Sea Grant\u2019s coastal construction and erosion specialist since 1978. He serves on the science panel that advises the N.C. Coastal Resources Commission, and has participated in many state, regional and national research and outreach efforts.<\/em><\/p>\n\n\n\n

North Carolina Sea Grant<\/a> is pleased to continue to be a partner in national efforts to improve storm-surge data gathering and understanding. Those efforts are advancing thanks to the increased attention from the U.S. Geological Survey<\/a>, or USGS, to storm surge in and following Superstorm Sandy in 2012.<\/p>\n\n\n\n

USGS efforts to take the lead for the coastal storm-surge\/wave-elevation measurements are greatly appreciated. The upgrade to faster wave gauges is a significant step forward. I am now out of the gauge rapid-deployment business. But I will continue to help partners identify prime deployment locations during storms \u2014 and will continue the recordkeeping in my own backyard near the Intracoastal Waterway in Wilmington.<\/p>\n\n\n\n

Measurements of water levels and wave heights in specific storms obviously are important as part of a storm record. But that data also will be used in models for forecasting impacts of future hurricanes or other coastal storms that threaten our coasts.<\/p>\n\n\n\n

In North Carolina and other states, these data are used in emergency management and planning, such as floodplain mapping. Those records also are key factors in predictions that are used in flood-resistance designs for new buildings and retrofitting of existing structures.<\/p>\n\n\n\n

EARLY EFFORTS AND STORM RESPONSES<\/h2>\n\n\n\n

My interest in wave gauges goes back to 1978. At that time, they were too expensive to purchase in useful numbers.<\/p>\n\n\n\n

Even 20 years ago, local, state and national officials did not have precise measurements of the water flow during storms. Rather, they relied on \u201cwatermarks\u201d as historical records.<\/p>\n\n\n\n

That system had at least two major drawbacks, as Sam Houston of the National Oceanic and Atmospheric Administration<\/a>\u2019s Hurricane Research Division and I described in a paper presented at a conference of the American Society of Civil Engineers in 1997. The paper was in response to Hurricane Fran just the year before.<\/p>\n\n\n\n

We described common errors in post-storm watermark surveying \u2014 and recommended installation of storm-surge\/wave gauges at key points in advance of specific storms.<\/p>\n\n\n\n

\"spencer
Spencer Rogers adapted the design for a gauge that Andrew Kennedy developed as part of a Florida Sea Grant research project. NC Sea Grant file photo.<\/figcaption><\/figure>\n\n\n\n

The first problem was that no single agency was in charge. Nationally, many folks were collecting storm-related water data, including USGS, the U.S. Army Corps of Engineers<\/a>, the National Weather Service<\/a> and various researchers at state agencies and universities, including Sea Grant program staff and researchers.<\/p>\n\n\n\n

No single system or protocol was used to measure watermarks, or to maintain the records. Also, the marks recorded the highest water during a storm. While that is good information, it is much better to identify the ebbs and flows of storm surge and other water movement during and after storms \u2014 be they named or not.<\/p>\n\n\n\n

While watermarks note the peak at the worst of the storm, we do not know what time they occurred. (My home includes marks from Hurricane Fran in 1996 and Floyd in 1999 \u2014 along with a handwritten record of approximate timing.)<\/p>\n\n\n\n

If we use watermarks with errors in storm-surge models, then we are building errors into those models. Gauges, on the other hand, offer a hydrograph that is needed to calibrate the models.<\/p>\n\n\n\n

Originally, the National Ocean Service<\/a>\u2019s tide gauges were designed for navigation. They were not optimized to survive hurricane conditions. In the worst conditions, they often failed. Their daily water records were not helping us in storms.<\/p>\n\n\n\n

Beginning with Hurricane Rita in 2005, USGS began extending its century of work in measuring streams and rivers to deploying pre-storm gauges.<\/p>\n\n\n\n

My focus on gauges started through a collaboration with Andrew Kennedy. While a researcher at the University of Florida, he designed units that would be dropped from helicopters to measure offshore waves, as part of a Florida Sea Grant project in the early 2000s.<\/p>\n\n\n\n

\"gauge
Rogers secured his gauges up and down the coast, including in Kure Beach. Photo by Spencer Rogers.<\/figcaption><\/figure>\n\n\n\n

I liked his design but I saw a more direct need to measure waves and storm surge near buildings. So we made arrangements to obtain and adapt them for use in North Carolina \u2014 to have them on call when a storm threatened. The goal was to place these gauges at predetermined locations based on the storm\u2019s track.<\/p>\n\n\n\n

At one point, the USGS gauges would cost up to $50,000 each, but officials realized that as technology improved, the prices were dropping \u2014 down to $1,000 or even $500 each for Kennedy\u2019s designs and our adaptations that were funded by a North Carolina Sea Grant minigrant.<\/p>\n\n\n\n

We let USGS know what we had in hand. Rick Luettich, director of the University of North Carolina at Chapel Hill\u2019s Institute of Marine Sciences<\/a>, or IMS, also had gauges for his research. North Carolina Sea Grant started deployments in 2006, with several years in which we did not have severe storms to test the process.<\/p>\n\n\n\n

But when Irene threatened North Carolina in 2011, the three groups \u2014 Sea Grant, IMS and USGS \u2014 were ready to cover deployment in different parts of the state. Kennedy, now at the University of Notre Dame in Indiana, came down to join our team (see map). This was a great advance over Hurricane Isabel in 2003, when we really needed the gauge-based measurements, but had to rely on watermarks.<\/p>\n\n\n\n

\"gauge
The gauges included Rogers’ contact information so that they cold be returned and data recovered even if moved via the storm surge. Photo by Michael Halminski.<\/figcaption><\/figure>\n\n\n\n

After Sandy \u2014 first designated a hurricane, then a superstorm \u2014 hit the East Coast in 2012, USGS was tasked with collecting storm-surge and other water data. Based on our experience, we encouraged them to move from slower stream-flow measurements to the wave gauges for storm surge.<\/p>\n\n\n\n

At the time, the USGS storm-surge gauges would only sample every 30 seconds, comparable to their century of stream-gauge recording history. Unfortunately, more accurate wave sampling requires about one-second sampling. I admit that I sounded a constant refrain at every opportunity I could during discussions among national partners: We need wave gauges that sampled faster.<\/p>\n\n\n\n

USGS agreed and was able to start purchasing wave gauges to meet nearshore and inshore needs. For Hurricane Joaquin in 2015 and a 2016 winter storm, we saw successful deployments.<\/p>\n\n\n\n

As North Carolina is within a primary area for USGS, I no longer will be dashing about to deploy gauges before storms. I have kept some of our North Carolina Sea Grant gauges for ongoing research and outreach. Others have been shared with the Mississippi-Alabama Sea Grant Consortium<\/a> for a project on Dauphin Island, which was affected by hurricanes such as Katrina and Ivan.<\/p>\n\n\n\n

ONGOING COLLABORATIONS<\/h2>\n\n\n\n

Now, with equipment and deployment much better refined thanks to USGS, I see a key issue to address: How to optimize useful data collection. That leads to defining \u201cuseful.\u201d I suggest the most important applications of these gauges are likely to be ones that lead to:<\/p>\n\n\n\n