Development of a High Water Mark Database and Display System for Coastal Flooding Events in Delaware

Project Status

Delaware is well-known for being affected by coastal storms, both tropical systems and extra-tropical storms (Nor’easters), and has been hard hit in recent years from Hurricane Irene in 2011, Superstorm Sandy in 2012 and the Mother’s Day Storm in 2008. Specifically, loss of life and damages done to the natural and built-up environment due to severe coastal flooding is likely the most significant natural hazard facing Delaware today. Unfortunately, for Delawareans, its geographic location, low-lying elevation, high rates of relative sea-level rise, and expanding coastal population and development, is making Delaware increasingly susceptible to abnormally high tides and storm surge. There exists a need for improved collaboration among Delaware state agencies and regional organizations to better analyze, monitor, and document the magnitude and extent of coastal flooding.

High water marks (HWMs), typically observed as water stains on building walls or debris lines on the street or beach, are arguably the best method for capturing the maximum depth and extent of a flood. They are also used to help in disaster recovery planning and allocation of insurance claims, among others. Together with maximum measurements during a storm from traditional tidal gages (also known as peak storm tides), HWMs are excellent resources for validating hydrodynamic models, such as Delaware Bay Operational Forecast System (DBOFS, used in the Delaware Coastal Flood Monitoring System) and the NOAA ET-Surge model, assessing the severity of a storm, and developing planning procedures. There is no formal collaboration among Delaware organizations in the collection of HWMs or technical infrastructure in place for sharing HWMs or peak storm tide data with each other or the public.

The project aims to facilitate solving these issues by:

  • Hosting two workshops to foster collaboration among all Delaware agencies and organizations
    involved with collecting or using HWMs/peak storm tide data,
  • Developing a database for storage of HWM/peak storm tide data for each flooding event,
  • Developing a publicly available website for distributing and mapping the database,
  • Testing the feasibility to significantly increase spatial and temporal coverage of monitoring flood levels through developing low-cost pressure sensors at strategic coastal locations, and
  • Laying the framework for future collaborations in mitigating damages due to coastal hazards.

Outreach groups such as Delaware Sea Grant and the Delaware Environmental Monitoring and Analysis Center (DEMAC) will utilize the resulting data sets, associated maps, and other derived products to enhance public awareness and K-16 education of coastal issues in Delaware.