Lost Space Design Analysis

A figure grounding design analysis of “lost space” for urban cooling in Lents neighborhood in Portland OR. Using remotely sensed data, and vector files I identified areas that are underutilized for heat mitigation.

What does NDVI tell us about lost space for extreme heat mitigation and urban cooling in the Lents neighborhood of Portland, Oregon?

In 2021, the Pacific Northwest experienced an extreme heat event and some areas in Portland broke records, hitting a high of 112 ˚F. Certain locations around Portland were even hotter on the ground due to urban heat islands and lack of tree cover. A study by Cassandra Bent using data from Portland State University’s Sustaining Urban Places Research Lab (SUPR) evaluated temperature data and demographic data, determining that St. Johns and Lends neighborhoods had the highest temperatures, lowest incomes, and larges proportions of communities of color.

Using GIS, I evaluated building footprints, roads, parks, and NDVI. NDVI stands for normalized difference vegetation index, and it uses remote sensing technologies to determine vegetation density based on the differences between red, green, blue, and infrared reflectivity. The imagery used for this analysis was taken August 8, 2018, which is ideal for this analysis because it represents what vegetation health looks like in the hottest summer months.

It is important to consider that NDVI is classified only for Lents neighborhood. If one were to look at NDVI in August across all of Portland, Lents would show significantly less vegetation than the areas of Portland with dense tree canopy, like the West Hills and Mount Tabor. Figure 1 shows a comparison of vegetation and lost space. Areas in white are areas taken up by buildings and streets, which By comparing existing vegetation and lost space, there are clear patterns of lost space especially around major roadways, like NE 82nd Avenue (running N/S along the West side of Lents), I-205 (running N/S through the center of Lents), and SE Foster Road (running diagonally NW/SE). The Springwater corridor (running diagonally SW/E), shows a lack of vegetation directly where the paved bikeway is, but also shows a clear line of trees and vegetation directly alongside it.

The furthest SE corner of Lents shows sparse vegetation, and is the location of Willamette National Cemetery. Despite the fact that the cemetery is covered by grass, the reflectivity of the lawn shows that the vegetation here is dry, unhealthy, and ineffective for urban cooling. Although there could be more urban greening done in residential areas of Lents, because they don’t face the issue of sightline safety, it is clear that transit-oriented design has resulted in vegetative patterns that exacerbate heat events.

History of Lents Neighborhood                                          

The history of Lents neighborhood, urban renewal, and development of the highway system is important to consider alongside these spatial patterns. Originally home to the Clackamas, Kalapuya, and Molalla tribes, white settlers began to develop along the Sandy river and in 1855 the federal government resettled these tribes at Grand Ronde.[1] The town of Lents was originally created in 1892, and was composed of “lower income Jewish, Chinese, German and Irish families” and was historically neglected by city planners.[2],[3]  In 1912, Lents was annexed into the city and in the 1930s, the Home Owner’s Loan Corporation (HOLC) yellow-lined Lents and the city of Portland developed the 82nd state highway which, “took customers away from Lents downtown”.[4],[5] In the 1970s, I-205 was constructed straight through the center of Lents, removing at least 500 homes and businesses and splitting “the community in half and created a mental barrier between eastern and western Lents”.[6] In 1998, Lents was still the home to many low income families and racial minorities, and the Portland City Council created an urban renewal area in Lents to “combat blight”.

[1] Trimet. “A cultural history of the neighborhoods along the I-205 light rail project”, April 2007.

[2] PDX History.com. “Lents, Oregon”. October 2016.

[3] Wong. “Lents: discover diverse sights and flavors in the East Portland neighborhood”. December 2021, Travel Portland.

[4] PDX History.com“, Lents, Oregon”.

[5] Trimet. “A cultural history of the neighborhoods along the I-205 light rail project”.

[6] Ibid.

Policy & Planning Takeaways

Many plans and policies aim to increase greening in Lents. The 1995 Lents neighborhood plan, policy no. 3 includes objectives for aggressive greening and planting of trees, but specifies that these efforts should “not conflict with future High Capacity Transit”.[1] The city of Portland’s 2015 Climate Action Plan includes Object 14, to “reduce risks and impacts from heat, drought and wildfire by preparing for hotter drier summers with increased incidence of extreme heat days”, and the 2017 progress report discusses revegetation efforts in Johnson’s creek through the East Lents Floodplain Restoration project. Although policies and plans are intended to increase vegetative cover in Lents neighborhood, it is clear that the transit-oriented focus of this space is prohibitive of actual progress.

Climate change and extreme weather patterns are only increasing, and unless fast action is taken Lents, and other similar neighborhoods cities will continue to value automobile transit over the lives of their residents. 

[1] Lents Neighborhood Association, “Lents Neighborhood Plan 1995”. Adopted March 1996. Portland Gov.com.