08 November 2019

Urban Agriculture for Phoenix Sustainability

Welcome Back. I apologize if you’ve been waiting to learn what happened with my idea to convert the farm’s long inactive dairy barn to an indoor vertical farm. (For the few who may have missed those blog posts, five years ago, I reviewed Indoor Farming, then featured the barn in a photo addendum, Indoor Farm Barn Addendum

Sadly, before I developed a business plan, they rented the barn to a beef cattle and chicken venture, which has since ended. The barn is now being used for storage and miscellaneous.

But since you’re here and I’m going on about agriculture, you might be interested to learn about the citywide analysis of Phoenix conducted by researchers with Arizona State University and Google, Inc. I was attracted to the study by the topics covered--urban agriculture (not indoor), sustainability and remote sensing.

National Research Council
consensus study report,
EPA bases sustainability on the principle that everything that we need for our survival and well-being depends, either directly or indirectly, on our natural environment. To pursue sustainability is to create and maintain the conditions under which humans and nature can exist in productive harmony to support present and future generations.

The National Environmental Policy Act (NEPA) of 1969 (enacted 1 January 1970) committed the U.S. to sustainability, declaring it a national policy. NEPA’s most significant outcome was the requirement that all executive Federal agencies prepare environmental assessments and environmental impact statements that describe the potential environmental effects of proposed Federal agency actions.

United Nations Sustainable
Development Goals
Over 100 nations have enacted national environmental policies modeled after NEPA. Further, in 2015, all United Nations Member States adopted 17 Sustainable Development Goals. Goal 11 is to make cities inclusive, safe, resilient and sustainable.

Achieving Phoenix’s Sustainability Goals
Phoenix is the fifth largest and second fastest growing U.S. city. The subtropical desert climate allows year-round crop production with irrigation, but climate change and growing population are water resource concerns.

In 2016, with substantial community input, the Phoenix City Council adopted eight 2050 Environmental Sustainability goals toward becoming a Sustainable Desert City, as envisioned in the city's General Plan.

The researchers set out to quantify the benefits of urban agriculture for achieving desired outcomes associated with three of the city’s sustainability goals: eliminate "food deserts," provide open green spaces, and reduce energy and CO2 emissions from buildings.

Three Phoenix 2050 Sustainability Goals addressed by study
(from iopscience.iop.org/article/10.1088/1748-9326/ab428f).
Urban Agriculture for Sustainability Goals
Urban agriculture or urban farming is pretty much what you would expect--producing food in a city or heavily populated municipality--except there is normally an element of commerce. The food is grown to be sold.

Eliminate Food Deserts
To address food deserts, the researchers estimated the total annual amount of food that urban agriculture could produce based on available area and most suitable crops.

The area potentially available for urban agriculture included unpaved vacant lots, flat rooftops and building façades amenable to growing plants vertically with trellises, cages or the like. The area of vacant lots was derived from an inventory of all vacant property. Rooftop and vertical surface areas were derived from 2014 lidar building footprint data provided by the US Geological Survey.

Lidar-derived 3D buildings and trees in downtown Phoenix
(from lib.asu.edu/geo/news/robust-usgs-lidar-data-now-available).
(Lidar, an active remote sensing method that uses a pulsed laser, is increasingly employed in diverse fields, especially for airborne mapping of terrain and preparing 3D building models.)

Crop suitability was ranked, based on estimated water use, historical yields and supermarket retail prices. The area devoted to each crop was proportional to its suitability.

Open Green Spaces
The researchers addressed the open green space provision by repurposing unpaved vacant lots as urban farms or community gardens.

When urban agriculture on vacant lots added open green space to an area without a public park, they considered that area no longer underserved. They also estimated how the added open green space could improve walkability.

Building Energy and Emissions
The researchers estimated the reduction in building energy that would result from the increased insulation afforded by rooftop agriculture. The difference between electrical power needed with and without rooftop agriculture was used to estimate the reduction in CO2.

Example of rooftop agriculture
(from www.growingmagazine.com/rooftop-farming-an-alternative-growing-system/).
Wrap Up
The study found that, if fully implemented, urban agriculture could supply 183,000 tons/year of food, providing produce in all food deserts and meeting 90% of fresh produce consumption; increase green space area by 17%, reducing underserved areas by 60%; and reduce building energy use by nearly 125,500 MWh, potentially displacing 51,270 tons of CO2 per year.

Overall, the analysis highlights the importance of merging a data-driven framework with local information and serves as a template for other city sustainability assessments. Thanks for stopping by.

Urban Agriculture:
Sustainability: www.epa.gov/sustainability/learn-about-sustainability#what
National Environmental Policy Act: en.wikipedia.org/wiki/National_Environmental_Policy_Act
UN Sustainable Development Goals: sustainabledevelopment.un.org/sdgs
Goal 11: Make cities inclusive, safe, resilient and sustainable: www.un.org/sustainabledevelopment/cities/

Phoenix 2050 Environmental Sustainability Goals: www.phoenix.gov/sustainability/goal
Phoenix videos on becoming a carbon-neutral city:

Phoenix urban agriculture assessment in Environmental Research Letters: iopscience.iop.org/article/10.1088/1748-9326/ab428f
Article on study on EurekAlert! website: eurekalert.org/pub_releases/2019-09/asu-tpg092719.php
Article on lidar and available lidar data sources on Geospatial World website: www.geospatialworld.net/blogs/did-you-know-the-sources-for-free-lidar-data/

My 2014 blog post about the application of airborne lidar for detecting stone walls in a forested area, Stone Walls Photo Addendum.

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