The use of ERDDAP in a self-monitoring and nowcast hazard alerting coastal flood system
Authors: Darroch Louise , Thomas Gardner , Margaret Yelland , Christopher Cardwell , Emma Slater , Elizabeth Bradshaw , Justin Buck , Robert Jennings , Andrew Hale , Jennifer Brown 
Published: March 2021

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&lt;p&gt;In the UK,&amp;#160;&amp;#163;150bn of assets and 4 million people are at risk from coastal flooding. With reductions in public funding,&amp;#160;rising sea levels and&amp;#160;changing storm conditions, cost-effective and accurate early&amp;#160;warning&amp;#160;flood&amp;#160;forecasting&amp;#160;systems are required.&amp;#160;However, numerical tools currently used to estimate wave overtopping are based on tank experiments and very limited previous field measurements of total overtopping volumes only.&amp;#160;Furthermore, the&amp;#160;setting of tolerable hazard thresholds&amp;#160;in&amp;#160;flood&amp;#160;forecasting models&amp;#160;requires site-specific information of wave overtopping during storms of varying severity.&amp;#160;&lt;/p&gt;
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&lt;p&gt;The National Oceanography Centre (NOC) are&amp;#160;currently developing&amp;#160;a new nowcast wave overtopping alert system&amp;#160;that can be deployed in site-specific&amp;#160;coastal settings&amp;#160;to detect potentially dangerous&amp;#160;flood&amp;#160;conditions in near real-time&amp;#160;(NRT)&amp;#160;while&amp;#160;validating&amp;#160;operational&amp;#160;forecasting&amp;#160;services.&amp;#160;At its core, it utilises a&amp;#160;prototype overtopping sensor&amp;#160;and&amp;#160;an instance of&amp;#160;the National Oceanic and Atmospheric Administration&amp;#8217;s&amp;#160;ERDDAP&amp;#160;data server&amp;#160;in&amp;#160;a&amp;#160;self-monitoring&amp;#160;and alerting&amp;#160;control&amp;#160;system.&amp;#160;In-situ&amp;#160;detection will be&amp;#160;performed&amp;#160;by&amp;#160;WireWall, a&amp;#160;novel&amp;#160;capacitance wire&amp;#160;sensor that&amp;#160;measures&amp;#160;at the high (400 Hz) frequencies required to&amp;#160;obtain&amp;#160;the distribution of overtopping volume and horizontal velocity on a wave-by-wave basis.&amp;#160;The sensor&amp;#160;includes&amp;#160;on-board data processing and 2-way telemetry&amp;#160;to enable automation&amp;#160;and control.&amp;#160;The telemetry posts&amp;#160;regular health summaries&amp;#160;and&amp;#160;high-resolution (1 sec)&amp;#160;hazard data (produced by&amp;#160;the&amp;#160;on-board processing) using&amp;#160;the standard&amp;#160;internet protocol (https) to an open&amp;#160;ERDDAP&amp;#160;server&amp;#160;so data are freely available via an application programming interface (API) alongside other&amp;#160;NRT&amp;#160;and delayed-mode&amp;#160;global coastal ocean and weather information&amp;#160;for&amp;#160;further&amp;#160;data exploration.&amp;#160;ERDDAP allows&amp;#160;NRT hazard&amp;#160;data to be accessed&amp;#160;by statistical algorithms and visual applications,&amp;#160;as well as receiving&amp;#160;alerts&amp;#160;that are also fed&amp;#160;to&amp;#160;messaging queue points&amp;#160;(RabbitMQ)&amp;#160;that&amp;#160;can be monitored by&amp;#160;external systems.&amp;#160;Combined, this will enable&amp;#160;automated&amp;#160;health monitoring&amp;#160;and&amp;#160;sensor operation&amp;#160;as well as offer the potential for downstream hazard management tools (such as navigation systems and transport management systems) to ingest the nowcast wave overtopping hazard data.&amp;#160;To&amp;#160;integrate&amp;#160;data&amp;#160;with wider systems&amp;#160;and&amp;#160;different disciplines,&amp;#160;ERDDAP&amp;#160;data sets&amp;#160;will be enriched with common and well-structured metadata. Data provenance, controlled vocabularies,&amp;#160;Quality Control and&amp;#160;attribution&amp;#160;information embedded in&amp;#160;the&amp;#160;data workflow is fundamental to ensuring user trust in the data and any products generated, while&amp;#160;enhancing&amp;#160;FAIR&amp;#160;data&amp;#160;principles.&amp;#160;&lt;/p&gt;
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&lt;p&gt;The new nowcast wave overtopping alert system&amp;#160;will be tested in 2021 during field deployments of multiple&amp;#160;WireWall&amp;#160;systems at&amp;#160;two high energy&amp;#160;coastal&amp;#160;sites in the UK.&amp;#160;Such data are crucial for validating&amp;#160;operational&amp;#160;flood forecast services&amp;#160;as well as protecting local communities&amp;#160;and minimising transport service disruptions.&amp;#160;The addition of&amp;#160;SMART monitoring optimises sensor maintenance&amp;#160;and operation,&amp;#160;reducing&amp;#160;the&amp;#160;costs associated with&amp;#160;teams travelling to the site.&amp;#160;Using&amp;#160;ERDDAP&amp;#160;embedded with well-structured metadata&amp;#160;enables&amp;#160;machines to&amp;#160;access multiple&amp;#160;flood&amp;#160;parameters&amp;#160;through a single&amp;#160;point that abstracts users from the complexities associated with the source data,&amp;#160;offering the potential for further&amp;#160;data&amp;#160;exploration&amp;#160;through modelling or&amp;#160;techniques&amp;#160;such as machine learning.&amp;#160;&lt;/p&gt;
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