Building to conserve: Quantifying the outdoor water savings of residential redevelopment in Denver, Colorado

Abstract

Outdoor water use represents up to half of total urban water demand in many semi-arid and arid cities and presents a climate adaptation challenge in urban centers. As indoor efficiency and reuse improves, outdoor use amounts to an increasingly large portion of consumptive urban water demand. Infill development, or the redevelopment of single-family properties to more dense multi-family and mixed-use developments, is a growing trend in urban planning; however, the influences of infill on outdoor water demand are poorly understood. The current work utilizes a remote sensing-based methodology to calculate parcel-scale irrigation rates in Denver, Colorado and applies a novel resampling methodology to model the impacts of redevelopment on outdoor water use. Results for 2018 showed irrigation rates varied by almost 250 mm between park and commercial land uses, and mean single-family irrigation rates of 224 mm exceeded multi-family rates by 70 mm. In the Berkeley neighborhood, modeled redevelopment of 1,347 single-family parcels (39.5%) resulted in a 102,000 m3 (83 acre-feet, or 30.2%) reduction in outdoor use. Citywide analyses indicate reductions of 141,000 m3 (114 acre-feet, or 0.76%) of residential outdoor use per one percent increase in redeveloped single-family parcels. These savings are equivalent to new annual supply for 181 four-person households and may provide significant contributions towards climate adaptation. Results highlight the importance of the continued integration of land use and water supply for demand management within the urban planning process.