How to Reduce Floods, Droughts and Water Pollution naturally

For most Canadians, It’s all too easy to take water for granted. We turn on the tap and out comes fresh, clean water from a reliable source. However, we cannot survive without it for the most basic tasks: drinking, cooking, power, cleaning, washing, etc. In Canada, half-a-billion dollars is currently spent on wastewater treatment, but what will happen when the country’s population, as projected, rises by 24 per cent over the next 20 years and 68 per cent in the next 40 years?

Canada | March 20, 2018
Reading Time : 5 minutes

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Challenge

Canadian household use 3.2 billion cubic meters of water a year. Historically, we settled near watercourses, but increasing development and urbanization have led to humans interrupting the water cycle, burying watercourses, building impermeable surfaces that prevent infiltration, and designing stormwater drainage to get water away from us as fast as possible. This resulted in less water infiltrating into the ground to replenish our aquifers and increased flooding by the inadvertent increase of flows in watercourses, as well as high costs of centralized storm sewer systems. Simultaneously, cars and industry increased pollution in the environment.

Canada’s projected future population growth will result in rising demand for water, space for housing, infrastructure, and potentially increase pollution. At the same time, rainfall is predicted to become ever less reliable and more extreme, thus putting more pressure on our reserves and increasing the chance of flooding.

We are already seeing these strains and impacts become more regular: “Day Zero,” in Cape Town, South Africa, when the city’s water source will run dry; and with flooding in Canada currently costing almost $600 million each year. To be a successful and resilient community, avoiding the associated impacts and rehabilitation costs from water-related incidents, we must be designing for these future challenges now. We must be Future Ready.

Solution

Pushing water away from the urban environment, and focusing it into rivers has clearly caused issues. Current thinking is that a restoration of the water cycle and a decentralized stormwater management approach could help alleviate some of the current challenges. Low Impact Development (LID) systems are techniques which aim to maintain the water regime post development, by storing and infiltrating water on site, and releasing it at a controlled rate. Looking to the natural process of water flow, such as reducing flow rate, careful selection of vegetation, and encouraging infiltration, can also be very effective at removing contaminants and sediment which can be very harmful to watercourses. Costs of installing and maintaining LIDs are similar to those centralized storm sewer systems, but are significantly more effective at reducing water quality impacts.

You have probably seen these at new developments in the form of ponds or landscaped depressions. The LID approach has been around for some time; however, it is often not fully utilized due to concerns regarding:

Groundwater flooding (rising water table)
Groundwater quality impacts
Ongoing maintenance and associate costs
Long term functionality

How we can help

Our Water Resources team has extensive experience in successfully designing and integrating these systems into new developments across Canada, such as Cham Shan Temple , Ontario and Starling, Alberta) Our approach typically considers a wider context of water use and concerns, seeking to use innovative approaches to reduce runoff at source as well as balancing other water uses, such as at our award-winning Earl Bales project, Ontario.

Abe Khademi, Director of Water Resources, explains at a current development site: “We are proposing to import soils with a higher infiltration capability than existing, meaning that all drainage from houses will be able to be dealt with by discharging to the gardens, significantly reducing the area required for central stormwater management ponds.”

Our Water Resources team also has extensive experience combatting existing issues by identifying, adapting and retrofitting existing stormwater drainage systems and combined sewer overflows. We are currently working on studies to reduce combined sewer overflows, helping various municipalities develop master plans. We have also helped others prepare for the future by stress testing existing stormwater management systems, incorporating climate change scenarios to direct investment and policy and help ensure future resilience, such as at Revelstoke (British Columbia).

At WSP, we imagine tomorrow and create the enduring solutions for our evolving understanding of water management. The question is no longer, “Can we design stormwater systems which prevent our site flooding?” but rather, “What if we do this in a respectful way which preserves or reinstates the natural system?”