UBC professors devise water plan for future urban gardens in Vancouver

July 26, 2016

In January 2013, the City of Vancouver unanimously passed the Vancouver Food Strategy, an official roadmap calling for Vancouver to become a global leader in urban food systems, with the target of increasing city and neighbourhood food resources by 50 per cent by the year 2020.

Already known as a hotspot for urban agriculture development in Canada, the strategy sets out goals to grow the city’s food assets, such as community gardens, orchards, farmer’s markets, and urban farms– which the City aims to boost in numbers from 17 to 35 within the next six years.

All that development will need plenty of fresh water to support it, and with public interest in these initiatives continuing to blossom, two Peter Wall Institute Associates are working to shed light on the actual production potential of the city, based on availability of healthy soil, sunlight, water and nutrients. Dr. Mark Johnson and Dr. Nicholas Coops hope to gain insight into what impact agricultural development could have on water use within Vancouver.

“We’re developing approaches to effectively understand the water use implications of growing food in Vancouver, and we’re trying to use methods that would then be transferable to other areas as well,” explains Dr. Johnson, part of the Institute’s 2013-2014 Research Mentoring Program and an Associate Professor at the University of British Columbia’s (UBC) Institute for Resources, Environment and Sustainability.

According to Dr. Coops– Dr. Johnson’s mentor and member of the Department of Forest Resources Management at UBC – the modelling they are doing utilizes climate information, remote sensing data, and insight on plant water use. The maps eventually generated from the project will help identify the ideal zones for new urban agriculture, what kind of direct and indirect light is available in those regions and what water resources would be needed to keep plants alive and producing through the spring and summer months.

“People tend to overestimate how much water plants actually need,” says Dr. Johnson, adding that the choice of what type of water to use for these purposes is crucial as well.

“The only obvious water available to people is municipal tap water, which has been treated to drinking water standards and then is used for non-potable uses [in local food production].”

Besides encouraging more use of alternate water systems such as rain collection barrels, Dr. Johnson’s background in ecohydrology– the study of the interactions between water and ecosystems– has shown a need to measure the water required to bring a crop from seedling to table. This includes not just irrigation, but transportation, washing and processing needs as well. 

“That amount of water, depending on the crop, can be significantly more than what is actually used in growing,” he explains. 

The project uses water meters to monitor water use in urban agriculture. The meter is connected to a data logger to register time of water use relative to other environmental variables such as temperature and rainfall. 

The current Research Mentorship Project undertaken by Dr. Coops and Dr. Johnson, titled An Integrated Assessment of Local Food Production Potential and Water Use Implications, will help provide crucial information for city planners, policy makers and food producers.

“I think this is a piece of the puzzle for water planning for the future,” says Dr. Johnson. “As we look to climate change becoming an increasing concern, what that looks like here [in Vancouver] could be enhanced seasonality. So we might have longer dry spells in the summer.”

For Dr. Coops, the Institute’s Mentorship Program, which matches experienced Institute Associates with early to mid-career Faculty to support interdisciplinary research, has brought about a unique kind of collaboration. It’s the first partnership of this kind in his career, combining his expertise in forest management and remote sensing with Dr. Johnson’s focus on ecohydrology.

The Program also supports collaboration between the two researchers’ graduate students (Rory Tooke and Michael Lathuillière), and is the first time the quartet has conducted research in an urban setting. The results have been an innovative new cross-disciplinary approach to understanding urban agriculture development.

“The graduate students have developed a new model, which I think is unique,” explains Dr. Coops, who is the Canada Research Chair in Remote Sensing. The modelling technique brings together data on how much and how well vegetation will grow in certain areas, the amount of energy or sunlight required to ensure budding and fruiting along with information about local plant water consumption. He says it’s the first time these three factors have been linked to provide insight into agriculture carrying capacity across Vancouver in such fine spatial detail.

To do so, the project has partnered with the City of Vancouver to obtain remote sensing imagery, also known as Light Detection and Ranging (LiDAR), which is a technology that measures distance and other geographical features by illuminating a target with a laser and analyzing the light that is reflected. LiDAR is a recent technology which is becoming more frequently used in high-spatial resolution urban map-making.

“The main challenge is the acquisition of data, because the data is quite extensive,” Dr. Coops says.

“But the results allow incredible detail, such as predictions of vegetation growth across the city within individual home-owners backyards, local gardens, parks and other lands.”

Examples of LiDAR data inputs for the combined water use and food production model being developed by the project’s team. This example shows the area around UBC Farm. Insolation refers to the total amount of solar radiation energy received on a given surface area during a given time, and evapotranspiration is the sum of evaporation and the movement of water through plants into the atmosphere.

In addition to this data, Dr. Johnson plans to collect more specifics on plant water use under different conditions by placing sensors on plants, hoses, pipes and water meters in various local urban agricultural areas around Vancouver.

“We’re fairly close to the beginning [of the project],” Dr. Johnson says. Water use sensors were tested last August, but require a full growing season of data in order to test the models the team has developed.

“We want to encourage people to continue gardening and producing food,” says Dr. Johnson. “There are a lot of social benefits and community benefits that are derived from it.”

The researchers are now trying to obtain additional funding to develop a web-based tool to allow all Vancouverites the capacity to look at the conditions within their local neighbourhood and assess how much food could grow and the resulting implications on their water use.

“But we also need to think about where the water availability under future climates might be impacted by different uses, and start to make choices.”

Ultimately, Dr. Johnson says Vancouver is quite privileged with its relative abundance of fresh water. However, attention needs to be given to the type of water resources used as the city continues to move forward with its food sustainability goals.

“We might have constrained choices, but we’re not going to run out of water per se,” he reiterates. “The question comes down to the energy and resources that go into treating the water. The ideal situation is to match the quality of water with the use of that water.”