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By JoAnne Castagna

JoAnne Castagna is a technical writer/editor for the U.S. Army Corps of Engineers, New York District; e-mail: joanne.castagna@usace.army.mil.

The 2009 Atlantic Ocean Hurricane Season officially ended on November 30, but the U.S. Army Corps of Engineers is working on safeguarding coastal states in the Northeast from storm events that can occur now and in the future.

The Army 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. The GIS produces products such as electronic maps, reports and charts that show analysis results to perform many different missions and solve complex problems.

Reducing Beach Erosion

The Philadelphia District is using GIS to protect New Jersey’s shore from beach erosion.

In 2003, 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.

To restore the New Jersey shore and help protect it from future storms includes replacing sand along the shoreline. Beach nourishment is a costly process that includes obtaining sand from the ocean offshore using a dredging process and placing it on the shore.

A map shows “borrow areas” off the New Jersey Shore. (U.S. Army Corps of Engineers)

To minimize the cost and better manage the sand-replenishment work, the 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 Web site using GIS tools, which is helping to make this study a success.

“The goal of the New Jersey Alternative Long Term Nourishment Alternative Study is to address New Jersey’s beach-nourishment issues on a multi-project level, rather than on a project-by-project basis,” says J. Bailey Smith, project manager, Philadelphia District, Army Corps.

“Planning beach-nourishment projects with a systemwide, 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,” adds Smith.

To help the district share beach-nourishment information with each other as well as stakeholders and the public, it developed the New Jersey Regional Sediment Management Web site at https://w3.nap.usace.army.mil/NJALTN/default.aspx. The site is an interactive map with layers of various data, including aerial photos, bathymetry, environmental and geotechnical data, etc.

A map of the study area was created using ESRI’s ArcMap to organize the data to provide meaningful information about the project, providing the ability to visualize the data.

Using ArcGIS Server technology, the map was published to the Web, allowing any end 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.

Using the Web site allows them to see a base map that shows the New Jersey State boundaries and waterways. From there, users can study additional map layers that show the district’s available coastal data, including the following:

• Surf Clams & Fishery Data: Project managers are using this information to identify where sea life resides in the ocean. This will determine where they can and can’t dredge sand.

• Archaeological Data: Project managers are using this information to locate shipwrecks and other historical artifacts. This also will help determine where sand can be dredged.

• Sediment Samples: Project managers are using this information to identify the properties of sand sediment, such as size, so they can match the size of the sand they dredge with what’s needed to replenish the shore. Matching sand size maintains the shore’s environment, and this information also shows how sand is moving along the beaches and inlets on the New Jersey coast.

• Bathymetry Data (ocean depth measurements): Project managers use this information to identify ocean areas with potentially large quantities of sand to help prioritize dredging locations.

• Borrow areas (dredging areas): Project managers use this information to identify consistent, reliable sources of sand.

Additionally, the Web site provides features that help better view needed information. For example, users can adjust their map views by panning in and out, and magnifying. They also can use a measuring tool that allows them to obtain the actual size of land and water features.

In the near future, the Web site will include data from additional Philadelphia district coastal projects, as they’re collected. Historic data also will be converted as needed. The Web site already is proving to be a valuable resource for the district, their stakeholders and the public.

Safely Evacuating Communities

The Baltimore District is using GIS to safely evacuate communities around the Chesapeake Bay, a large body of water located in Maryland and Virginia that was one of Hurricane Isabel’s worst victims. Waves in the bay peeked at eight feet above normal, causing severe flooding that destroyed homes, vehicles, boats and businesses as well as caused millions of gallons of raw sewage to run into the bay.

If another Isabel were to hit today, the bay will be better prepared because of work being accomplished by the U.S. Army Corps of Engineers Baltimore District, which is creating Storm Surge Inundation Maps (i.e., flooding maps) using GIS for the Federal Emergency Management Agency (FEMA) National Hurricane Program (NHP).

A Google Earth overlay shows storm-surge inundation at Baltimore's Inner Harbor. (U.S. Army Corps of Engineers, Baltimore District)

Federal partners in the NHP include the Army Corps’ Planning Center of Expertise for Coastal Storm Damage Reduction, based at the Army 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 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 route maps showing the best roadways for citizens to evacuate and flooding maps to show citizens if their homes are in danger of flooding.

The Storm Surge Inundation Maps are a critical part of the NHP that has a mission to help protect communities and residents from hurricane hazards through various projects and activities, including conducting assessments as well as providing tools and technical assistance to state and local agencies in developing hurricane-evacuation plans.

“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,” notes Jared Scott, a GIS analyst with the Army Corps’ Baltimore District. “With GIS, these maps can be updated instantly with new information and provide quick results, which is important in emergency situations.”

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). These maps have proven to be extremely useful for preparedness for hurricanes or other natural disasters.