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What’s the best way to use geographic information system (GIS) technology to improve surveying and mapping? While many firms are beginning to employ modern GIS software “out of the box” to manage spatial information more efficiently and enhance their mapmaking capabilities, companies on the cutting edge are figuring out how to leverage advanced capabilities to create electronic maps that can be used as tools to analyze trends, conduct “what-ifs,” and provide input into decision-making processes related to land use and development. Such efforts are minimizing the risk to which citizens are exposed while improving their quality of life through use of land resources in other, more appropriate ways. Dewberry, a Fairfax, Va.-based engineering, surveying and GIS firm, is just one example of a company that has done such leveraging with an extremely broad scope. Dewberry’s efforts have resulted in widespread benefits for citizens, corporations and government agencies.
To coordinate and provide better local and state relief, the United States and its territories are divided into 10 FEMA regions. Rather than choosing one contractor to create a nationwide GIS-centric DFIRM, FEMA planned to implement Map Modernization primarily through regional indefinite delivery/indefinite quantity (IDIQ) contracts and state and local government cooperating technical partners (CTP). Dewberry, which had a solid history of serving FEMA for more than three decades, was awarded IDIQ and CTP contracts in several regions.
Geospatial Data Streamlining
At its core, GeoFIRM relies on a centralized, multiuser geo-database. In a GIS, geodatabases organize geographic data into a hierarchy of data objects. This technology makes it possible for project members to instantaneously view data, easily edit the database and readily access Dewberry DFIRM project data such as digital imagery, orthophotography, scanned paper FIRMs, LiDAR (light detection and ranging) and engineering data. Furthermore, GeoFIRM’s engineering and mapping teams can collaborate directly on geodatabase-driven projects via the Internet.
Dewberry built GeoFIRM around a Microsoft SQL database and ESRI’s ArcGIS software. ArcGIS, ESRI’s GIS solution for authoring, serving and using geographic information, contains a collection of software products and tools for building and developing a complete GIS. Using the geodatabase-centric ArcSDE technology in ArcGIS, GeoFIRM became Dewberry’s central repository for engineering and mapping spatial and nonspatial DFIRM data. GeoFIRM’s GIS architecture allows project members to focus more on adding value to the data in the geodatabase rather than on just delivering products such as raster maps and DFIRM databases.
Dewberry built a series of automated “toolkits” using the ArcObjects technology inside ArcGIS to assist project members in the new platform. The toolkits facilitate the modeling process automatically by managing the input and output requirements for each model or task. GeoFIRM provides tools for terrain, survey, hydrology, hydraulics, mapping and DFIRM production. According to Smith, the custom-created toolkits have increased engineering accuracy and quality while drastically reducing FIRM production cost and time.
“One of our key paradigms is to let the computer do what it can do best, which is a lot of number crunching, analysis, what-if scenarios,” says Ken Logsdon Jr., the manager of Dewberry’s GeoFIRM development team. “We let the computer run through a series of automated routines, and then GeoFIRM tools visually present the engineer or the geographer with the results at key stages of the process so they can make informed decisions and infuse better engineering and mapping judgment.
“Essentially what we built,” continues Logsdon, “is a system that’s scalable across our enterprise, revolves around industry-standard and industry-leading software and hardware components, and allows our team members to collaborate across the United States in appropriate teams with the best professional mix, while having access to all project data and edits in real time. While our teams are focused on adding value to the GIS database, we have the tools on the back end of the system that actually produce our product deliverables.”
Advances in remote sensing technology have made the acquisition of high-quality elevation data such as LiDAR more commonplace in flood-hazard risk assessment and mapping projects. LiDAR data’s increasing affordability has made it a technology of choice not only for flood-hazard mapping but also for a host of other applications, including emergency management, post-disaster damage assessment, environmental restoration and natural resources exploration. By incorporating LiDAR technology into GeoFIRM, Dewberry can provide FEMA with automated bare-earth, hydroenforcing, and quality control and analysis (QC/QA) techniques.
Dewberry has been involved in LiDAR mission planning, design and execution since the technology’s earliest application to flood mapping. The company’s team of remote sensing, geodesy and GIS specialists help plan, manage and execute every facet of a LiDAR mission so that the results meet the demanding requirements for flood mapping. From mission design to independent QA/QC, the team ensures that mission specifications meet project needs and resulting data attain the designed specifications.
While the availability of LiDAR data has helped to significantly increase the accuracy of the flood maps, it has become increasingly challenging to manage the huge datasets produced by LiDAR in a GIS. ESRI addressed this issue when it introduced the terrain datatype in ArcGIS 9.2. The software more efficiently stores large topographic data in both file-based geodatabases and SDE datasets, and it provides on-screen visualization in a dynamic triangular irregular network (TIN) format. Dewberry leveraged this technology in its GeoTerrain toolset within GeoFIRM and extended the usability of terrain data. Dewberry uses GeoTerrain in coastal and riverine (stream and river) studies and has delivered significant modeling and mapping efficiencies across various tasks for DFIRM production.
DFIRMs produced using Dewberry’s GeoFIRM software have helped protect the lives and property of more than 40 million people. For example, after Hurricane Katrina, Dewberry mapped the flood elevations along the coastlines of Mississippi and Louisiana, representing 19 counties. GeoFIRM’s GeoCoastal toolset enabled the project team to statistically analyze field survey data of observed high-water marks and to map inundation and debris limits. The resulting data were employed to help establish advisory base flood elevations that were used to guide recovery efforts from the catastrophic storm. Although recovery efforts for the 2008 hurricane season were just beginning at press time, Dewberry’s standing contracts with FEMA make it likely that the firm will provide similar services in the aftermath of these and other natural disasters.
While many land surveying firms struggle with understanding the concept of a GIS--and struggle even more with understanding how it can help invigorate their businesses--astute leaders of other firms are making the effort to learn the breadth and depth of the GIS technology they can access. Thus armed, they are able to creatively design solutions that wouldn’t have been conceivable a mere decade ago.
Sidebar: The FIRMIn 1968, Congress passed the National Flood Insurance Act and created the National Flood Insurance Program (NFIP). The act mandated that the nation’s flood zones be established in order to define locations subject to higher probability of flooding. Paper maps were created to show the location of 100-year floodplains. Property in a 100-year floodplain has a 1-in-100 chance to flood in any given year and, thus, is labeled a Special Hazard Flood Area (SHFA).
Specific building standards and flood insurance rates were assigned to SHFAs, and risk zones were established and designated by a letter or series of letters. AE Zone, for example, denotes a floodplain with a 100-year elevation, while VE Zone identifies flooding along a coastline. Shaded X Zone areas have a low to moderate risk of flooding and are located in a 500-year floodplain while nonshaded X Zone areas are outside a 500-year floodplain.
The result of detailed topographic and hydraulic studies was state-of-the-art paper Flood Insurance Rate Maps (FIRM) first printed in 1973. FIRMs became the official source of data for determining if a structure was located in a flood zone and were used to establish flood insurance rates and building codes.
As digital technology evolved, computer-aided design (CAD) files were used in the 1980s to process and produce paper FIRMs. In the 1990s Windows-supported applications were common on desktop computers, and FEMA answered with digital FIRMs in a GIS format called Q3. Because the floodplain data provided was compressed into a single layer of zones, Q3 maps were void of some paper map features such as base flood elevations, river cross sections, study data and river depths. GIS users produced maps using Q3 data, but FIRM users found Q3 and its quality-control procedures limited, and they continued to produce paper FIRMs for final flood-zone determinations.
Paper maps and Q3 data was pre-empted in 2004 when FEMA, Congress and the president recognized the value of DFIRMs and initiated the Map Modernization program. As part of its mission to reduce loss of life and property from all types of hazards, FEMA’s Mitigation Division oversees the production of DFIRMs, all of which are being released in GIS formats.