Guest editorial– Why Reservoirs are the Wrong Solution for Increasing Central Indiana’s Water Supply in a Changing Climate

The proposed Mounds Lake Reservoir has been touted as necessary for securing a reliable water supply for continued growth in central Indiana. A growing body of evidence, however, shows that the likely changes to precipitation patterns that will result from climate change point toward ground water aquifers as a much more reliable water source. Among these are changes are an increase in short term summer droughts, an increase in summer evapotranspiration, and an increase in total dormant season precipitation.

As climate change continues, summers are forecast to be up to 9 % drier according to research cited by the Union of Concerned Scientists in their publication Confronting Climate Change in the U.S. Midwest. The summers of both 2010 and 2011 were characterized by heat waves that corresponded with late summer droughts. These occurrences result from a strong ridge of hot high pressure that anchors itself over the central United States, forcing storm systems to ride over the ridge, often north of the border with Canada. The sinking air associated with these high pressure systems suppresses convection, preventing the formation of summer thunderstorms. As a result, several weeks of dry weather combined with high heat and evapotranspiration levels result in a rapid loss of soil moisture and low levels in stream and rivers. Although deleterious to surface water supplies, these short term droughts that only last a couple of months have little effect on ground water levels. While longer droughts like the one in 2012 may have a more measurable effect on ground water, it is still much less than the devastating effects they have on surface water flows.

In contrast, again according to the Union of Concerned Scientists, winter and spring precipitation is forecast to increase by up to 30% by the end of this century.  Since most ground water recharge occurs during the dormant season when evapo-transpiration rates are low, the near surface aquifers characteristic of the glacial till plain of central Indiana are expected to continue to see adequate direct surface recharge in spite of the drier summers. Further, the increase in dormant season precipitation is expected to lower the chance of long duration droughts that last more than 2 years. These long duration droughts are ones more likely to affect groundwater.The Indianapolis Metropolitan Area has already experienced minor water capacity shortages during the aforementioned droughts due to its reliance on surface water from White River and the existing reservoirs for the vast majority of its supply. In view of the shifts in precipitation patterns likely with climate change, Citizens Energy would be wise to look to ground water to diversify its water supply portfolio.

Kevin Tungesvick

 

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