Susquehanna River, Asylum Township, Bradford County, as seen from Marie Antoinette Overlook along US Route 6 (Photo by Nicholas A. Tonelli).
Contributors: Warren Brown; Peter Claggett, USGS; Jake Leizear and Susan Minnemeyer, Chesapeake Conservancy Conservation Innovation Center
For thousands of years human survival depended on the ability to look over the landscape and identify where to hunt, gather, farm and find shelter. Technology has dramatically enhanced our ability to visualize and interpret the landscape, and document that the health of our waterways depends on what happens on the land. The Environmental Protection Agency (EPA) and other federal, state and local government agencies have invested millions of dollars in studying how our Chesapeake Bay ecosystem functions. Even after decades of studies and data collection there is much more to learn.
In 2018, Chesapeake Conservancy’s Conservation Innovation Center (CIC) entered into a six-year cooperative agreement with the EPA to provide geospatial support to inform the management of pollutants entering the Chesapeake Bay. The agreement includes collaboration with a variety of partners, including the U.S. Geological Survey (USGS) and the University of Vermont Spatial Analysis Lab on the production of updated land cover, land use, and land change products for the watershed.
Improvements in data about land cover and land uses are providing new insights about how our watershed is changing, what that might mean for water quality and for achieving Bay restoration goals for 2025. Source data are collected primarily from aerial photography supported by the U.S. Department of Agriculture National Agricultural Imagery Program (NAIP) and Light Detection and Ranging (LiDAR) data supported by the USGS. The area mapped for the Chesapeake watershed spans 99,000 square miles, encompassing the full area of the 206 counties that intersect or are adjacent to the region. No other part of the country has as detailed land use data at this resolution for such a large area.
The dramatic new developments in land cover and land use mapping have been an advance in resolution with the release of the first one-meter product in 2016, as well as mapping change at this scale for the first time with products to be released in March 2022. Land use and land cover data have traditionally been produced for large regions at a 30-meter resolution, and forthcoming products at one-meter resolution represent a major advance. This increase in precision is providing much more detail and information about the landscape down to the scale of individual parcels, especially how it is changing over time.
Thanks to improvements in computer software programs and ancillary data layers, the new data are also novel for their categorical resolution, identifying over 50 categories of land use. The distinction between land cover and land use is critical. While land cover data tells us what is visible on the surface, land use data suggests how humans are interacting with the land. For example, an area of low vegetation would be described as such by land cover data, but land use data might identify the area as pasture for livestock, turf lawn or cropland–each having distinct economic uses and impacts on the environment and water quality.
To get from land cover to land use, the land cover dataset is re-classified using a wide range of additional factors including zoning, current uses, parcel boundaries, landfills, floodplains and wetlands. In the past, land cover data generated from lower resolution imagery would identify a swatch of tree canopy and record those acres as entirely forested. The use of more precise imagery can help detect smaller areas within that forest that are open fields, roads, agricultural fields or even housing. In addition, more precise data show small tracts of woods and individual trees in urban areas that were not detected in previous work. This gives us a more accurate look at tree canopy in the landscape and the benefits trees provide—even how fragmented forests and individual trees provide critical functions to reduce temperatures, manage stormwater and clean the air in urban neighborhoods.
One of the discouraging findings of the latest data analysis is that the landscape includes as much as 50% more impervious surfaces than were identified in previous studies. The good news is that these findings can help target remediation efforts and improved management practices on the highest priority areas.
The increased precision in land use and land cover data also allow for adjustments in policy. Data at this resolution maps urban forests across the watershed in a consistent manner, over consistent timeframes for the first time, illustrating how forests and tree canopy are changing.
The next release of data is expected in spring 2022 and should provide even more useful information about what human activities are occurring on the ground and how they are changing over time. This will allow states, local governments and conservation advocates to prioritize areas that are experiencing undesired changes for conservation and restoration, while enabling a more accurate assessment of progress on restoration and conservation initiatives.
High-precision data about land cover and land use are being used to support the Bay Program in several other critical areas including:
Understanding how water flows: High-resolution terrain data are displaying detailed and accurate networks of stream channels, roadside and agricultural ditches, and estimates of channel characteristics. These data will inform partners about how water moves throughout the landscape and where best management practices could be located to most effectively reduce nutrient and sediment loads entering the Bay’s tributaries.
Mapping and tracking best management practice opportunities: High-resolution datasets and modeling are being used to develop a data-driven, dynamic blueprint for conservation strategies in the Chesapeake Bay watershed. This information will help local governments and practitioners understand restoration opportunities that exist in their geographies, identify the suite of practices that will help move them toward their Watershed Implementation Plan goals, and track implementation of these practices to streamline the reporting process.
Synthesizing the data: The CIC provides geospatial planning and support to the Chesapeake Bay Program to create a comprehensive plan and structure that allows Bay Program partners to integrate geospatial data into management efforts. The team completed a user research study to gather information on how data and mapping decision support tools are currently used within the partnership and to develop recommendations on improving access to, and improving the usability of, geospatial information in support of achieving Chesapeake Bay Program goals.
These one-meter resolution land use and land cover data are foundational, authoritative and transformative to the Bay restoration effort. They represent a major and unprecedented advance in our collective ability to characterize the landscape and how it is changing through time. The CIC and USGS are dedicated to helping organizations use the data to make more effective and efficient conservation and restoration decisions.
In-text image credit:
- NAIP Imagery, Chesapeake Conservancy
- 1-Meter Land Cover, Chesapeake Conservancy
- 1-Meter Land Use, Chesapeake Conservancy
- Hyner View State Park, Susquehanna River, Clinton County (Nicholas A. Tonelli)
Lightning Update is a regular communication of the Chesapeake Conservation Partnership. Any opinions expressed are those of the authors and do not necessarily reflect positions of the Partnership or member organizations.
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