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Commission reviews satellite-based tree-canopy assessment and options to track change over time
Summary
Commissioners heard about a satellite-sampling canopy assessment that estimates citywide tree and shrub cover and discussed repeating the exercise periodically to track canopy change.
A commissioner presented a satellite-sampling assessment of Delaware City’s tree and vegetation cover, and the Shade Tree Commission discussed using the method to track canopy changes over time.
The presenter described the methodology as sampling Google Earth or similar satellite imagery, overlaying the city boundary, and randomly sampling dots to determine land-cover types. The commission reviewed the results, which the presenter summarized as roughly 24 percent tree and shrub cover citywide, 24 percent pervious herbaceous cover (including pasture) and 24 percent farm-field crops in the last sampled data set. The presenter said the sampling dated from about 2019–2020.
Commissioners discussed how removing row-crop acreage and converting it to development would change the citywide numbers; the presenter calculated that moving row crops into development would raise cumulative canopy coverage in one hypothetical adjustment to roughly 30 percent. Members discussed limitations of satellite sampling — for example, distinguishing rooftops from asphalt — and noted the sampling is not a gold-standard LIDAR analysis but is relatively quick and inexpensive to update.
Commissioners suggested the city could repeat the sampling periodically, or obtain contracted annual low-vegetation layers as part of existing aerial-imagery services. The presenter said the spreadsheet and methodology can be shared with the commission and that the commission’s canopy spreadsheet is already used for maturity and canopy assumptions in plan reviews.
The commission agreed to request the presenter’s data and to consider a schedule for repeating the assessment to monitor progress toward canopy goals.
