Annual Residential Development in the Delaware River Basin, 2013 and 2014

Watershed Protection

Annual Residential Development in the Delaware River Basin, 2013 and 2014

Methodology – Estimating annual residential development area
The objective of this study was to estimate the annual total land area devoted to new residential development within the Delaware River Basin (DRB). Isolating development in the Delaware River Basin is a challenge, since data on residential development are available for political geographic units, which do not follow watershed boundaries. In order to overcome this challenge, we used residential construction data from the smallest geographic units available - in this case, Census County Subdivisions (generally equivalent to municipalities). Figure 1 shows the difference in area for counties (left) and county subdivisions with a portion of their area within the Delaware River basin (boundary shown in dark green).
 
The general methodology for estimating annual residential development is to compute the product of the number of residential parcels developed and the average area per residential parcel. To estimate the number of parcels affected, we used building permit data available at the Census County Subdivision level. We used parcel data to compute average residential parcel size. In addition, we added adjustments for the portion of permits representing new development (i.e. excluding permits for renovations), and the portion of the Census County Subdivision area within the DRB. Finally, we separated the data into 1-unit parcels (i.e. single family residential), and multi-unit parcels.

Published: October 2016
Authors: 
Lara S. Hanson
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