Changing river flow

Stream flow in the southern Interior has changed over the last 30 years. Spring runoff starts earlier and autumn rains come later, extending the period of low summer flow. More precipitation falls as rain than as snow in autumn, therefore snowpacks are smaller. Smaller snowpacks result in lower stream flow in summer. These trends will continue if climate continues to warm.

Upper Similkameen Rivers (Source: Leith and Whitfield, 1998)

Longer, warmer summers and lower, summer stream flows will affect hydroelectric power generation. In the future, some reservoirs may not fill to their present levels, and the amount of electricity generated from them will be less than today.

Dry lake bed, Okanagan Valley (Ole Westby)

The water balance: running a deficit

Summers are dry and hot in southern Interior valleys such as the Okanagan. Climate warming will affect the water balance in these valleys. Less precipitation may fall as snow, and less water would be stored in the mountains over the winter. Evaporation and plant transpiration will increase during the longer, warmer summer. Lake levels may fall, while the demand for irrigation and municipal water will increase.

Typical water use inside a home

Typical water use inside a home (Source: American Waterworks Association)

Did you know?
Hydroelectric reservoirs supply 90% of British Columbia's electrical power needs.

Did you know?
On average, each person uses over 300 L of water at home every day. This is equal to about one full bathtub. The amount increases to about 600 L per day when we include our indirect use of water through businesses and services that support us. If we had to retrieve this amount of water, it would take some 75 trips with a 4 L jug in each hand.

As demand for water increases, what can be done to conserve and share this precious resource?

References

Leith, R.M.M. and Wakefield, P.H., 1998: Evidence of climate change effects on the hydrology of streams in south-central B. C.; Canadian Water Resources Journal, v. 23, n. 3, p. 219-230.