Reservoirs Effects on the Interannual Variability of Winter and Spring Streamflow in the St-Maurice River Watershed (Quebec, Canada)

Abstract

The aim of this study was to test three main hypotheses about the interannual variability of streamflow downstream from dams: (1) an almost similar long-term trend in interannual variability, (2) low variability of flow, and (3) its independence (no link) from climate variability. To test these hypotheses, the interannual variability of winter and spring streamflow downstream from three reservoirs (Gouin, Manouane, and Matawin) which induce an inversion of the natural cycle of streamflow (maximum flows in winter and minimum flows in spring) was compared to the interannual variability of streamflow in natural rivers (measured at the Matawin and Vermillon stations) over the period from 1932 to 2008 in the St-Maurice River watershed. As far as the interannual variability of flow is concerned, its long-term trend is not homogeneous downstream from the three reservoirs in both seasons. However, downstream from two reservoirs, changes in streamflow were observed to be different from those in natural rivers (no significant trend downstream from the Taureau reservoir, on the Matawin River, and significant decrease in spring flow downstream from the Manouane reservoir). Finally, coefficient of variation values for minimum flows are higher downstream from reservoirs than in natural rivers, despite the fact that watershed surface area is larger for regulated rivers than for natural ones. As for the link with climate variability, analysis of the correlation between climate variables (temperature and precipitation) and mean winter and spring daily streamflow reveals that winter streamflow downstream from the Taureau reservoir is not correlated with any climate variable, whereas spring streamflow is positively correlated with rainfall and negatively Water Resour Manage (2011) 25:3661-3675 correlated with maximum temperature. Thus, downstream from reservoirs, the interannual variability of streamflow depends on climate during the spring, but not during winter.

Analysis of the Impacts of Man-Made Features on the Stationarity and Dependence of Monthly Mean Maximum and Minimum Water Levels in the Great Lakes and St. Lawrence River of North America

“…In addition, this method is sensitive to small changes in mean and variance, unlike other tests [16]. Because the Lombard test equations have been presented in several papers (e.g., [16][17][18]), they are not described herein. According to this test, at the 95% confidence interval, one concludes that the mean or variance of the series changes significantly whenever S n > 0.0403.…”

The Management Modes of Seasonal Floods and Their Impact on the Relationship Between Climate and Streamflow Downstream From Dams in Quebec (Canada)

“…Many authors who have highlighted the heterogeneous nature of the impacts of dams on streamflow have questioned this interpretation (e.g. Piron and Neumann, ; Assani et al ., ; McManamay et al ., ). Most of these authors, however, have highlighted a spatial, rather than temporal, heterogeneity. Factors that can account for such spatial heterogeneity are dam type, dam operation, dam storage capacity and geographical setting.…”

“…Poff et al ., ), and others look at the effect of climate on seasonal and/or annual flows (e.g. Assani et al ., ). This is problematic because the scale of analysis can affect the relationship between climate and streamflow. Methods used to analyse the relationship between climate variables and streamflow downstream from dams may differ from one study to another, which may undoubtedly lead to differing conclusions. There have been no study yet of the impact of flood management mode on the relationship between streamflow downstream from dams and climate, even though floods are the main factor affecting the interannual variability of streamflow both in natural rivers and downstream from dams.…”

“…This topic, however, remains controversial because other studies have highlighted the effect of climate on the spatio‐temporal variability of streamflow downstream from dams (e.g. Naik and Jay, , ; St‐Jacques et al ., ; Assani et al ., , ; Jay and Naik, ; Zhao et al ., ).…”

Comparison of the Spatio-Temporal Variability of Annual Minimum Daily Extreme Flow Characteristics as a Function of Land Use and Dam Management Mode in Quebec, Canada

“…The mathematical basis for this method was described by [21] as well as [22]. Its application to the analysis of hydroclimate data was documented, among others, by [23]. In applying this method, the null hypothesis (absence of shift in mean or variance) is rejected at the 5% level when the Sn value of the Lombard test derived for observed hydroclimate series is larger than the (theoretical) critical value of 0.0403.…”