Snow key to water cycle

I am writing this article about Okanagan water from the passenger seat, as our truck crawls through a Coquihalla snowstorm. Under these conditions – fighting the elements – the snow seems like quite a bother and potentially dangerous judging from all the cars off the road. But from the point of view of long-term sustainability, snow is one of the most important elements of our Okanagan water cycle. In fact, most of the planning and infrastructure changes needed to help us adapt to climate change involve ways to adapt to changes in snow cover.

There is a lot of uncertainty about the effects of global warming, but scientists are quite sure that weather in the Okanagan will become less predictable than ever with swings between dry and wet years. As well as the increase in year-to-year variation, our winters are expected to become shorter and warmer on average, with less snow and more rain.

Paradoxically, a winter with above average precipitation (in the form of rain) could be the precursor to a summer of water shortages. The reason is that we rely on snow for water storage. Slowly melting snow recharges our groundwater, keeps flows in the streams for fish, and trickles down into our reservoir lakes, delaying their draw-down in the hot summer irrigation season.

If all the precipitation comes as rain, we have limited capacity to hold it and excess water must be released over the dams in the winter and spring to reduce the risk of flooding. Come summer, it is gone.

Water managers in the Okanagan are thinking ahead about how to adjust to potential changes in snow pack. One way is to increase the number and size of reservoirs we have in the upper parts of the watershed. Although these require substantial engineering and infrastructure costs, if we can capture and hold the rainwater, we can make up for the loss of some snow storage. Another way is to slow down the rainwater as it runs off the land and direct it into wetlands or infiltration basins to refill our aquifers.

A third way is to increase the efficiency of irrigation and water use in agriculture, industry and at home. Strategies range from expanding the re-use of treated wastewater – offsetting fresh water demands – to replacing ornamental turf-grass with drought-tolerant plants. It may seem improbable on a hot July day, but putting in drip emitters and water-wise landscaping will be an important way that individual Okanagan residents adapt to less snow in the mountains in January.

We do have some things to be thankful for. Many cities around the world depend on melt-water from rapidly receding glaciers. Once the glaciers are gone, it will be hard for those cities to adjust to sharp reductions in water supply. We can also be thankful that right now we have the knowledge, resources, and opportunity to adapt our water systems for long-term sustainability in the Okanagan, and thankful for any good snowfalls.

This column is produced by the Allen Brooks Nature Centre and Partners. Guest Collumnist: Anna Warwick Sears.  For feedback please email editors Mary Stockdale: [email protected] or Patrick Allen: [email protected].

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