ALMONTE - Get ready for more heat, more rain, and less available water in the next century.
While it certainly is long, long term forecasting, a study carried out by Mississippi Valley Conservation is predicting that there will be less water to go around.
“Because of the increase in temperatures, we are seeing an increase in evapotranspiration, which results in a 25 per cent reduction in available water,” said Paul Lehman, general manager of Mississippi Valley Conservation, speaking at a special conference looking at the impacts and lessons of the drought of 2012 at the Almonte Old Town Hall on Saturday, Jan. 12. “The type of drought conditions we saw this past year will start to become more prevalent.”
Using the 1974 to 2002 as a base period, the study looked at three future periods: 2010 to 2039, 2040 to 2069 and 2070 to 2099.
“As we project into the future, we will see an increase in precipitation but it won’t be significant,” said Lehman. “We are projecting increases in temperature pretty consistently throughout the year… (for) minimum temperatures, particularly in the winter, will increase the most.”
With dryer conditions, Lehman warned that this could result in increased shoreline erosion and greater variability in summer water levels.
“Our stream flows are going to change,” said Lehman. “We will see lower summer flows,” by as much as 44 per cent lower, “but we will see higher flows in fall and winter,” by as much as 70 per cent, with a greater risk of flooding in the fall and winter periods, with a 26 per cent reduction in annual stream flows – at a time of rising water demands.
“Higher water surface temperatures, we are starting to see that already,” said Lehman. In time, we will also see “lower flushing rates, which will ultimately degrade water quality.”
One way in which these challenges could be met would be to increase reservoir capacity along the Mississippi River by 25 per cent.
“It is a major, major undertaking,” admitted Lehman, who added that the MVC and other water agencies may have to use risk-based management strategies, while our culture of water usage – such as how we water crops and grass – will also have to change.
However, Lehman cautioned that “the analysis we did is pretty preliminary. It is a preliminary risk assessment that only used one climate model.”
He added that “I wouldn’t put 100 per cent confidence in a model,” but noted that it gives researchers and water managers a good idea “of what to expect.”
By projecting out nearly a century into the future, he admitted that “the further out you project…the more uncertain it becomes. It’s something we have to be aware of.”