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The 2009 Atlantic Ocean hurricane season officially ended Nov. 30, but the U.S. Army Corps of Engineers continues work on safeguarding coastal states in the Northeast from storm events that can occur now and in the future. The Corps’ Philadelphia and Baltimore Districts are using GIS to reduce storm-related problems such as flooding, beach erosion (loss of sand), destroyed homes and businesses, and loss of life.
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These were the results of Hurricane Isabel in 2003. Isabel’s powerful winds and rough waves bombarded the Atlantic Coast and was the deadliest and costliest hurricane that year, taking the lives of 51 people and costing taxpayers $4.22 billion, according to 2009 figures.
Reducing beach erosion
Hurricane Isabel put New Jersey’s shore community in a state of emergency. Along the 125-mile-long shoreline, Isabel created waves 10 feet higher than normal, killing one surfer and causing flooding and severe beach erosion.
Replacing sand along the shoreline can restore the New Jersey shore and help protect it from future storms. However, beach nourishment is a costly process that involves dredging sand from the ocean floor.
To minimize the cost and better manage the sand-replenishment work, the Philadelphia District, in collaboration with the state of New Jersey, initiated a study to consolidate its beach-nourishment efforts and prioritize sources of sand for beach-nourishment projects. In addition, it created a website using GIS tools, which is helping to make this study a success, said J. Bailey Smith, project manager, Corps Philadelphia District.
“The goal of the New Jersey Alternative Long-Term Nourishment Study is to address New Jersey’s beach nourishment issues on a multi-project level rather than on a project-by-project basis,” said Smith. “Planning beach nourishment projects with a system-wide, regional mindset, including the use of GIS, helps to reduce shore protection costs and resources utilized and minimize environmental impacts, as well as help to identify and critique alternative shore-protection strategies for the New Jersey coast.”
To help the district share its beach-nourishment information internally as well as with stakeholders and the public, it developed the New Jersey Regional Sediment Management website. The website (https://w3.nap.usace.army.mil/NJALTN/default.aspx) presents an interactive map with layers of data including aerial photos, bathymetry, and environmental and geotechnical data from the study area with a base map of the New Jersey coast as a backdrop.
A map of the study area was created using ESRI ArcMap. Using ArcGIS Server technology, the map was published to the web, allowing any user with access to an Internet browser the ability to view the data. The interactive nature of the map helps engineers, scientists, and stakeholders visually review, manage, and analyze the geographically referenced data from multiple perspectives. Starting with a base map of the New Jersey state boundaries and waterways, users can study additional map layers that show the district’s available coastal data, including the following:
- Surf clams and fishery data — Project managers are using this information to identify where sea life resides. This will determine where they can and can’t dredge sand, so as not to harm any sea life.
- Archaeological data — Project managers are using this information to locate ship wrecks and other historical artifacts. This will help determine where sand can be dredged so as not to harm historically valuable sites.
- Sediment samples — Project managers are using this information to identify the properties of sand sediment, such as its grain size, to match the size of the dredged sand with what’s needed to replenish the shore. This information is also showing them how sand is moving along the beaches and inlets on the New Jersey coast.
- Bathymetry data — Project managers are using this information to identify areas of the ocean with potentially large quantities of sand to help prioritize dredging locations.
- Borrow areas (dredging areas) — Project managers are using this information to identify consistent, reliable sources of sand.
Additionally, the website provides features that help better view the information they need. For example, users can adjust map views by panning in and out, magnifying, and using a tool that measures the size of land and water features.
In the near future, the website will include data from additional Philadelphia District coastal projects, as it is collected. Historic data will also be converted as needed. The website is already proving to be a valuable resource for the district, its stakeholders, and the public.
Safely evacuating communities
The Corps Baltimore District is using GIS to safely evacuate communities around the Chesapeake Bay. During Hurricane Isabel, waves in the bay peeked at 8 feet above normal, causing severe flooding that destroyed homes, vehicles, boats, and businesses and caused millions of gallons of raw sewage to run into the bay.
Today, if another Isabel were to hit, the bay will be better prepared because of work being accomplished by the Corps Baltimore District. The district is creating Storm Surge Inundation Maps or flooding maps using GIS for the Federal Emergency Management Agency’s (FEMA) National Hurricane Program (NHP). The maps are a critical part of the NHP, which has a mission to help protect communities and residents from hurricane hazards by conducting assessments and providing tools and technical assistance to state and local agencies in developing hurricane evacuation plans.
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Federal partners in the NHP include the Corps’ Planning Center of Expertise for Coastal Storm Damage Reduction, based at the Corps’ North Atlantic Division, and the National Oceanic and Atmospheric Administration.
Using GIS Storm Surge Inundation Maps, community leaders will be able to see what areas may be vulnerable to flooding during different categories of hurricanes and quickly determine how citizens can safely evacuate. They will be able to do this by overlaying the Storm Surge Inundation Maps with population data and aerial photography. Areas of concern include hospitals, fire and police stations, housing units, hotels, emergency shelters, bridges, and roadways.
From this information they can create maps showing the best evacuation routes and maps to show citizens if their homes are in danger of flooding. The Baltimore District’s GIS staff completed worst-case scenario storm surge inundation maps for the state of Maryland (Chesapeake Western Shore), District of Columbia, and Northern Virginia (counties located along the Potomac River).
According to Jared Scott, a GIS analyst with the Corps’ Baltimore District, Storm Surge Inundation Maps are bringing hurricane evacuation plans into the 21st century. “In the past, these maps were crafted in multiple ways, including manually calculating and drawing data by hand, and updating these maps took months or even years,” said Scott. “With GIS, these maps can be updated instantly with new information and provide quick results, which is important in emergency situations.”
With GIS technology, the Corps is reducing the probability of flooding, beach erosion, destruction of homes and businesses, and loss of life.
JoAnne Castagna, Ed.D., is a technical writer-editor for the U.S. Army Corps of Engineers, New York District. She can be reached at joanne.castagna@usace.army.mil.
