The UrbanFootprint Land Consumption module quantifies the land converted for development in future land use scenarios. Comparative scenario results demonstrate the impacts of different growth patterns, which may take place as infill/redevelopment or greenfield development. Converted land area is classified according to its existing condition, yielding five categories – agricultural, woodland, other greenfield, urban vacant, or urban redevelopment.

Analysis is run at the scale of the project canvas (generally parcels or census blocks), yielding a spatial output layer and corresponding data table; both can be used within UrbanFootprint for mapping and data exploration, and exported. The module also reports individual and comparative scenario results via summary charts, and generates a spreadsheet summary in Excel format.

Methodology

The UrbanFootprint Base Canvas and painted scenarios represent development via Building and Place Types. For future scenarios, analysis assumes that the application of building and place types to the parcel or census block geometries of the scenario canvas leads to the consumption of all the “developable” area within each, provided that the incremental density of new growth meets a minimum specified threshold. The analysis process is summarized in Figure 1, and described in the following sections.

Figure 1. Land Consumption Analysis Flow

Calculations

The module first calculates the incremental housing and employment densities for each painted parcel or block to assess its development status. Incremental density is measured as the increase in dwelling units or employment in the scenario being analyzed as compared to the Base Canvas, divided by the developable area in the parcel or block. Developable area refers to unconstrained parcel area within a parcel or block.

The module then filters the canvas for parcels or blocks that have incremental densities greater than the minimum specified density thresholds, which are defined by users as input parameters. The total developable area within each parcel or block meeting the minimum condition is considered as land consumed.

Lastly, the module classifies the land consumed into the five land cover categories: agricultural, woodland, other greenfield, urban vacant, or urban redevelopment. The total area of each “consumed” parcel or block is multiplied by its proportional share within each of the five categories, yielding land consumed by each category.

Base Condition Categorization

The categories of the base condition are derived from the National Land Cover Dataset (NLCD) 2011 for all of the United States but Hawaii. For Hawaii, the National Oceanic and Atmospheric Administration (NOAA) Coastal Change Analysis Program (C-CAP) Land Cover 2011 dataset is used. Both are derived from satellite imagery and assign values to 30m by 30m pixels.

Using a raster-based calculation, the module counts the number of pixels in each parcel/ block by NLCD classification. For the “developed” NLCD classifications, the pixels are counted towards the “Urban Vacant” category if the parcel/block is vacant and “Urban Redevelopment” if the parcel/block had any dwelling units or jobs on it. Using these counts, we get the proportional share that each of the five categories contribute to that parcel/block. This process is illustrated in Figure 2.

Figure 2. Base Condition Categorization

Input Parameters

The housing and employment densities of new development on a parcel or block must meet a minimum threshold in order for the developable land area of a parcel or block to be considered as consumed. By default, these cutoffs for increases in dwelling unit (DU) and jobs density are 0.05 DU/acre or 0.05 jobs/acre, respectively. Parcels/blocks with painted development at densities that fall beneath these thresholds are not included as consumed land. This allows users to introduce “conservation” land uses in future scenarios without the changes being considered as urban development.

The minimum development density thresholds can be set individually for each scenario via the Analysis Module Parameters Manager, as shown in Figure 3.

Figure 3. Land Consumption Module Parameters Manager

Output Metrics

The Land Consumption module generates a spatial output layer and corresponding data table; both can be used within UrbanFootprint for mapping and data exploration, and exported. The module also reports individual and comparative scenario results via summary charts, and generates a spreadsheet summary in Excel format. The attributes of the spatial output/data table are summarized in Table 1.

Table 1: Land Consumption Module Outputs