COASTAL FLOODING & SOLUTIONS, Workshop July 2020

A Coastal Storm Hazard Early Warning and Monitoring System for Delaware

Location:
CFMS Model, Delaware
Submitted by:
John Callahan
Delaware Geological Survey, University of Delaware, Associate Scientist
Project URLs:

Project Description

It has been widely documented that Delaware is highly vulnerable to the impacts of coastal storms along its Delaware Bay, Atlantic Ocean, and Delaware Inland Bay shores. Delaware’s coastal regions contain large areas of low, open, flat coastal terrain, where even small vertical increases in water levels along with high waves result in large horizontal extent of flooding, with growing residential and commercial development and critical natural resources within or adjacent to these coastal regions. Minor and major flooding from coastal storm surge and high tides are expected to get worse as sea levels continue to increase due to climate change.
The Delaware Coastal Flood Monitoring System (CFMS, http://coastal-flood.udel.edu/), released in 2013, is an online web application designed to provide coastal flood forecasts and real-time conditions for the Delaware coast. Display and content are specifically geared to translate NOAA modeled flood forecasts for local community managers and emergency personnel in an easy-to-use manner. The Delaware CFMS generates 48-hour tidal and wind forecasts, inundation maps, and road elevation profiles for each of 15 communities along the Delaware Bay shoreline from New Castle, DE to Lewes, DE. Each community can subscribe to receive e-mail and text message notifications of potential flood conditions over the 48-hour forecast period. The Delaware Weather Hazard Index (DWHI, http://cema.udel.edu/applications/dwhi/) is another online application designed to display NOAA modeled forecasts for Delaware. However, the DWHI tool expands beyond flooding along the coast to also include hazards from wind, temperature, precipitation, ice/snow, and thunderstorm activity for the entire state. With support from the Delaware Department of Natural Resources and Environmental Control (DNREC) Delaware Coastal Programs, data and information provided by the CFMS and DWHI applications are being combined into a new Coastal Storm Hazard Early Warning and Decision Support Dashboard for Delaware. The new “Coastal Dashboard” will include weather and flood forecasts from NOAA model guidance products, real-time weather and hydrologic conditions, and historical coastal storm data.

Key Successes

Currently in use by various state, county, local agencies, NWS, and others including local residents, during flood events. Easy to use and focused on local communities. Anecdotal support that predicted water levels on our site were good. Continue to receive (small) funding from state partners.
In addition to local training and conference presentations in Delaware, we’ve been invited to present the CFMS to several regional groups: Delaware River Basin Committee (DRBC), NASA Mid-Atlantic Coastal Resilience Institute (MACRI), joint meeting with IOOS/MARACOOS and NOAA CO-OPS.

Challanges

Additionally, the following services/solutions are future needs.

1) Inclusion of northern part of the state (higher elevations more influenced by precipitation/run-off, urban areas of Wilmington). Need to investigate the difference between DBOFS water level forecasts and actual water levels, although very few inland water level sensors exist and stormwater drainage issues occur in many locations in southern Wilmington.
2) Move beyond bathtub model. The current Delaware CFMS uses a bathtub model to display inundation maps focused on each coastal community. Waves, high tides, storm surge attenuate as they propagate up tributaries, flooding adjacent areas albeit at a lower elevation during observed at the coast. The rate of attenuation and the exact nature of flooding at more inland locations is unique per location and dependent upon topography, channel/tributary depth, length/sinuosity of the tributary, surrounding land use (marsh vs agricultural vs residential), protective barriers or water control structures (dikes, dune systems) that are in place, etc.., as well as meteorological conditions.
3) Validation of “predicted or statistically extrapolated” inland water levels: anecdotal evidence from citizen-science contributions (e.g., mobile apps such as Coastal Observed, King Tides) or statistical performance validation which would require installation of water level sensors.
4) Wider adoption/awareness of tool, which would require additional outreach and advertisement.
Any question regarding this posting, email edl@gatech.edu
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