Smart city story: Technology and trees

Planting for the future: Measuring tree watering to grow the urban forest

The City of Calgary has over half a million trees on public land and 1.5 million privately owned trees. This is a remarkable and valuable accomplishment: our arid grassland climate means trees don’t live in many areas, much less thrive.

Trees provide many benefits to both citizens and wildlife. They increase our air and water quality, reduce erosion, provide food and shelter to animals, raise property values and enhance our neighbourhoods- to name a few.

The urban canopy is both a public investment and community resource. As such, the City has a mandate to protect existing trees and grow new ones.

Establishing new growth

One of the ways The City ensures trees grow for the next generation of Calgarians is by planting new trees and ensuring their survival.

Watering a tree is the single best way to ensure it establishes in a new location - and thrives.

However, when you are responsible for over 9,000 newly planted trees each year, there are a number of factors to consider:

  • How often is each tree watered?
  • How much water does each tree receive?
  • How do we make sure a tree isn’t over or underwatered?
  • How do you keep watering practices consistent between vendors who care for our trees?
  • How do you ensure this data is collected accurately, consistently and in a useful way?

Public trees are watered for the first five years of their life, so The City needed to ensure we could answer these questions to track our work, protect citizen investment in the urban forest and save on replacement costs for failed trees.

Until recently, there was no dependable, measurable way to confirm City trees were receiving correct amounts of water at correct intervals.


Water and electricity working together safely

The idea of using a water flow sensor was proposed. City trucks already had portable GPS and cellular modems- which could give wireless connectivity to transmit the flow data in real time.

The idea was simple, but the ask was complicated: water and electricity rarely work well together.

The solution required multi-departmental collaboration and expertise from disciplines including sensor design and integration, vehicle mechanics and wiring, modem hardware and firmware customization, and GIS software development.

So far, eight watering trucks now have an industrial grade water flow sensor. A GIS application allows viewing of disperse amount on each tree in real-time.

Reports were also available from the system to provide overall tree watering progress per day and per truck.

Measuring success

The results of the program:

  • Costs came in under budget: projected cost was 150k, and final spend was 126k. This saved citizens money while protecting their initial investment in newly planted trees.
  • Improved public visibility to show effective tree watering to Calgarians
  • Reduced unnecessary water consumption for new trees
  • Reduced death of new trees due to overwatering/underwatering
  • Further trucks are being fitted for water flow sensors to ensure continued effective and efficient use of City resources