Introduction

In Minnesota, high-quality elevation data are essential for agriculture and precision farming, natural resources conservation, flood risk management, infrastructure and construction management, water supply and quality, coastal zone management, and many other business uses. 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 Minnesota. The status of available and in-progress 3DEP baseline lidar data in Minnesota 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 $13.6 million in new benefits annually to the State. The top 10 Minnesota 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 Minnesota

The Minnesota Geospatial Advisory Council’s 3D Geomatics Committee (refer to text box), with guidance from the National States Geographic Information Council 3DEP for the Nation project, has written the Minnesota Lidar Plan (Minnesota Geospatial Advisory Council, 3D Geomatics Committee, 2021). The goals of the plan include (1) collection of quality level 1 lidar data, (2) collection of data statewide within about 5 years, and (3) development of more detail regarding lidar-derived information.

Water Supply and Quality

Detailed topographic information is essential to understanding the dynamics of water resources in Minnesota and knowing how to best mitigate human influences on the hydrologic systems, such as nutrient and sediment loading. Having updated elevation information at higher densities than previously available provides substantial time saving and greatly eases the identification of water conveyance features (fig. 2). Accurate modeling of the surface flow of water across the landscape is important for a myriad of applications, and high-density lidar provides the necessary detail for these applications.

Forest Resources Management

Comprehensive forest inventory information is desired for multiple land uses and can be used in many applications, such as generating industry estimates of wood fiber and timber, assessing wildfire risk, and compiling foundational data for a host of other mitigation efforts in forest and habitat health monitoring. However, the costs of maintaining such information collected through fieldwork continue to be a large annual expense and long-term challenge. According to Jennifer Corcoran (Minnesota Department of Natural Resources, Remote Sensing Program, written commun., September 25, 2020), “The Minnesota Department of Natural Resources conducted a pilot study using high-density lidar data to create model-assisted forest inventory, showing that costs can be cut by about 55 percent, including the cost of lidar. This new approach enables the analysis of valuable three-dimensional information across all lands, not just State-administered lands.”

Infrastructure and Construction Management

The Minnesota Department of Transportation has relied on aerial imagery, photogrammetry, and precision field data to create high-accuracy surveys for more than 40 years. However, these data have their limitations. Today’s lidar sensor technology and the capability of very high density scanning enables laser pulses to shoot through gaps in the forest canopy and reach the bare earth below. This allows engineers to use lidar-derived models to perform analyses of areas remotely, thereby reducing field time and safety risks. High-density lidar can also be used to identify archaeological sites and help avoid harmful impacts on them; calculate line of sight; determine the best location to build; accurately calculate cut-and-fill for road planning; identify heights of in-place assets; and, overall, identify and map streets, highways, railroads, grades, levees, buildings, and other constructed features in much greater detail and at a lower cost than ever before (fig. 3).