June 18, 2007

Winnipeg River: Better than Ever

Filed under: Droughts, Floods, Precipitation

There is little doubt that increasing atmospheric concentrations of greenhouse gases will generally cause the Earth to warm and alter precipitation patterns in various parts of the globe. Changes in precipitation and temperature will thereby impact hydrological systems, and the global warming alarmists love to show images of floods or dried-up streams to make the threat of the anthropogenic greenhouse effect look as bad as possible. Indeed, the global warming scare has deep roots in the drought of 1988 over the southeastern United States that created an anomalous low flow on the Mississippi River (recall headlines about the Mississippi River drying up?). If you have forgotten, the summer of 1988 also gave us the huge wildfires of the West (Yellowstone Park burned in that summer and fall) as well as Hurricane Gilbert, and those images of how global warming will impact us have lived on powerfully ever since.

The literature on how the enhanced greenhouse effect will alter streams and rivers shows us everything from floods to record-breaking low flows, and of course, both will be bad for humans and natural ecosystems. Floods are definitely bad, but in low flow situations, agriculture will be severely impacted, direct human use of water would need to be curtailed, and if the stream provides hydropower, the impacts can be severe in the energy sector.

Canada is a mid-to-high latitude, northern hemispheric land mass where global warming is expected to be far greater than in other parts of the world, and this warming will surely be felt by the streams across their country. An article has appeared in a recent issue of Journal of Hydrology entitled “Streamflow in the Winnipeg River Basin, Canada: Trends, Extremes and Climate Linkages” by Scott St. George of the Geological Survey of Canada and the University of Arizona. The final sentence of the abstract caught our eye as he wrote “the potential threats to water supply faced by the Canadian Prairie provinces over the next few decades will not include decreasing streamflow in the Winnipeg River basin.” We knew immediately that we had a Winnipeg winner on the line! Let the world know that funding for his work was provided by Manitoba Hydro, the Manitoba Geological Survey, the Prairie Adaptation Research Collaborative and the Natural Sciences and Engineering Research Council of Canada.

St. George explains that “Several Canadian provinces rely heavily on hydroelectric energy, and generate substantial revenue from the sale of electricity to other provinces and the United States. In Manitoba, hydropower provides nearly 95% of total electricity production.” The Winnipeg River (Figure 1) is a major player in the hydropower game, and for a variety of reasons, this river is the focus of his research. St. George collected flow gauge, temperature, and precipitation data from throughout the basin from 1924 to 2003 and performed extensive statistical analyses on trends in the data as well as on the relationship through time between streamflow and climate.


Figure 1. Map of the Winnipeg River basin showing the locations of the climate station and stream gauges (from St. George, 2007).

Well, contrary to what the global warming crusade would lead you to believe, there is good news from the Great White North. St. George states “Trend analysis indicates that mean annual flows of the Winnipeg River have increased substantially since 1924.” As seen in the figure below of monthly flow levels, six meet the “statistically significant“ criterion, all six show an increase in flow, and the six months with substantial increases in discharge all occur in the winter season. St. George notes “the presence of similar trends at upstream gauges demonstrates that direct anthropogenic interference in the hydrological system is not the primary cause of these changes.” These trends are real, robust, and statistically significant.

Figure 2. Linear trends in monthly streamflow for the Winnipeg River at Slave Falls from 1924 to 2003 (from St. George, 2007)

Is global warming causing snow to melt thereby increasing the flow in the winter season? Absolutely not. St. George discovers that “Streamflow between October and March is most strongly related to precipitation between August and October, with significant relationships observed using lags up to 6 months.” Sure enough, he finds that “Rising winter discharge across the basin has coincided with increasing annual and seasonal precipitation” and that “This change largely reflects increases in summer (May–July) and autumn (August–October) precipitation, as no significant trends were observed for winter (November to January) precipitation.”

Recall that the author collected temperature data for the study area, and if you are not a sworn believer in global warming, please have a look at this sentence “No significant trends were identified in annual, monthly or seasonalised temperature records.” This alone is an astounding finding and very little comment about it appears in the paper. Recall that climate models predict the greatest warming to occur in interior portions of large landmasses of the Northern Hemisphere. St. George collects temperature data for this area in interior Canada from 1924 to 2003 and finds no warming – amazing. Can you believe that you didn’t see this on the front pages of newspapers worldwide?

If you think drought and low flows might be an ever-increasing problem in the Winnipeg River Basin, St. George found that the year of lowest flow was 1977 (back in the hey-day of the global cooling scare). The next lowest flow in his 1924-2003 study period was in 1931, followed by 1988, 1932, 1940, 2003, 1911, 1941, 1930, and 1981 (you do the math)! Years of highest river discharge, from record high to lower, are 1974, 1966, 2001, 1927, 1969, 1950, 1970, 1965, 1971, and 1997.

St. George gathers the data, finds an increase in summer precipitation (we are sure the agricultural community is disappointed in having more summer rain), no change in temperature (not likely going over well in the climate alarmist camp), more discharge in the Winnipeg River (and we presume an increase in hydropower production), and no changes in flooding or low flows. In the final sentence he writes again “it seems likely that the potential threats to water supply faced by the Canadian Prairie provinces over the next few decades will not include decreasing streamflow in the Winnipeg River basin.”

Enough said!

Reference:

St. George, S. 2007. Streamflow in the Winnipeg River Basin, Canada: Trends, Extremes and Climate Linkages. Journal of Hydrology, 332, pp., 396-411.




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