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April Map of the Month – Chesapeake Bay Watershed Land Cover

April Map of the Month – Chesapeake Bay Watershed Land Cover

The Chesapeake Bay watershed is getting a digital update to accurately represent land use and land cover (LULC) on the landscape. Land cover is created using aerial imagery and computer algorithms to classify the physical landscape into categories such as forests, grasslands, cropland, wetlands, or impervious surfaces. With additional input, land use can be derived which describes how the landscape is used or managed by humans with categories such as agriculture, residential development, commercial development, transportation, recreation, or conservation.

Through a Cooperative Agreement spanning six states (and Washington, D.C.), six years, and with four major objectives, the Chesapeake Innovation Center (CIC), in partnership with the University of Vermont and Chesapeake Bay Program, is updating LULC data for the entire Chesapeake Bay watershed. The original LULC data was created using imagery from the 2013/14 timeframe. The current ongoing effort will provide high resolution LULC data based on imagery from the 2017/18 timeframe and also identify any changes that occurred over that time.

The first development of Bay-wide land cover and land use was done in partnership with the CIC using the data from Virginia’s own statewide LULC mapping effort. Virginia’s data was merged with common land uses for use in the Chesapeake Bay Program model. The 2017/18 data will only include localities in the Chesapeake Bay which are fully or partially within the watershed. Partial localities will still be mapped in their entirety.  

Currently, the CIC and partners are wrapping up the first phase in which local governments may provide input to the land cover data and ensure accuracy. Land cover will then be converted to land use, and the change in land use that occured between 2017/18 and 2013/14 will be identified. These detected changes are then applied to the Chesapeake Bay Program’s CAST model. This model integrates with watershed and estuarine models to capture nutrient loads from the landscape, so updated land use data over time is paramount to understanding how our decisions on the land impact water quality across the Bay watershed and in our local waterways.

Graphic of data, defined as circles, informing the Chesapeake Bay Watershed Land Cover Map

The final 2017/18 LULC data set will be downloadable and available by the end of 2021. This data can be used for land use planning, assessment of healthy watersheds, wetlands, habitat, solar suitability analyses, environmental justice assessments, and much more. The 2013/14 data has been widely used for a multitude of initiatives throughout the Bay watershed, the Commonwealth, and the region.

This month’s map showcases the existing 2013/14 data for the Chesapeake Bay watershed, developed by the CIC and partners. The data is at a 1-meter resolution so the detail can be seen at a fine scale – zoom in to view the data at a neighborhood level. Also, the percent of land cover in each locality is shown in a pie chart by clicking on one of the localities in Hampton Roads. When the new data is released, we will update the map to show the changes that have occurred.