Introduction

Connecticut has a diverse, largely forested landscape characterized by hills and low mountains in the Western Upland, hills in the Eastern Upland, ridges and broad valleys in the Central Lowland, and many beaches and harbors along the coast of Long Island Sound. Connecticut is manufacturing and service focused, ranking almost highest among the 50 States in the United States in personal income per capita (Hoyt and others, 2024). Due to Connecticut’s dense population, many people, especially the approximately 60 percent living near the coast, may be affected by climate-driven disasters. High-quality elevation data can inform the activities of many nongovernmental organizations and municipal and academic entities statewide, resulting in substantial economic impact. Government at the State and local levels relies on these data to support regulatory permitting, resource and infrastructure management, and various engineering and planning-level analyses. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features.

The 3D Elevation Program (3DEP; refer to sidebar) is managed by the U.S. Geological Survey (USGS) in partnership with Federal, State, Tribal, U.S. territorial, and local agencies to acquire consistent lidar coverage at quality level 2 or better (table 1) to meet the many needs of the Nation and Connecticut. The status of available and in-progress 3DEP baseline lidar data in Connecticut is shown in figure 1. 3DEP baseline lidar data include quality level 2 or better, 1-meter or better digital elevation models, and lidar point clouds, and must meet the Lidar Base Specification version 1.2 (https://www.usgs.gov/3dep/lidarspec) or newer requirements. The National Enhanced Elevation Assessment (Dewberry, 2012) identified user requirements and conservatively estimated that availability of lidar data would result in at least $4.40 million in new benefits annually to the State. The top 10 Connecticut business uses for 3D elevation data, which are based on the estimated annual conservative benefits of 3DEP, are shown in table 2.

Status of 3DEP in Connecticut

In 2015, the Capitol Region Council of Governments, on behalf of all nine regional councils of governments, received a grant from the Connecticut Office of Policy and Management to fund the statewide acquisition of high-quality lidar through the Regional Performance Incentive Program. The grant also leveraged funding from the Connecticut Department of Transportation and the Connecticut Department of Emergency Services and Public Protection. In 2017, Connecticut took delivery of statewide coverage of quality level 2 lidar data (fig. 2). Connecticut is currently processing statewide 3-inch orthoimagery and quality level 1 lidar data having a minimum of 20 points per square meter (ppsm) along the coast and 15 ppsm elsewhere, having been acquired and delivered in the spring of 2023 and anticipated in 2026, respectively, and incorporated into 3DEP.

Coastal Zone Management

According to the Connecticut Department of Energy and Environmental Protection (2020), “the Connecticut Coastal Management Act (CMA), effectuated in 1980, is the centerpiece of the State’s comprehensive coastal resource management program, building upon existing and new authorities. Responsibility for CMA implementation is shared by State and municipal levels of government. The CMA delineates a coastal management boundary, statutory policies, standards, and implementation procedures and defines government management responsibilities.” Mapping intertidal zone elevations, sea-floor bathymetry, and upland topography and seamlessly integrating these data can inform effective coastal zone management (National Oceanic and Atmospheric Administration, 2012). Lidar has the potential to improve coastal hazards modeling, impervious surface identification and analysis, and development of resiliency plans and storm response, all of which can help to protect Connecticut’s shoreline as well as its tourism and fishing industries.

Flood Risk Management

The availability of high-quality statewide elevation data can substantially improve the accuracy of flood maps and help to reduce onsite data-collection costs associated with flood risk mapping projects. More-accurate flood maps based on high-quality elevation data can be used to improve emergency preparedness and response. Connecticut experiences significant storm events, such as in September 2021, when remnants of Hurricane Ida produced heavy rainfall in parts of the State. Comprehensive lidar coverage enables detailed modeling, including dynamic 3D models of the overflow from streams and other water bodies affected by large storm events, catastrophic dam failures, and coastal overland storm surges. Quality level 1 lidar data can provide an enhanced ability to predict surface-water movement and inundation in high-risk coastal areas. Communities and agencies can use this information to design improved evacuation route plans and better protect the public in the event of a disaster.

Natural Resources Conservation

Connecticut is rich in natural resources and has a great diversity of habitat, landscapes, plant life, and wildlife. High-quality elevation data enable State, regional, and local governments to effectively implement natural resources conservation practices such as minimizing stormwater runoff, protecting tidal marshes and open space, siting trails, pursuing best agricultural practices, and identifying and protecting habitat, while reducing costs. Accurate lidar can increase Connecticut’s ability to protect natural resources and steward related recreational opportunities, both of which are economically relevant.