Harold Vigneault

Groundwater recharge trends in CanadaGeological Survey of Canada Contribution 20090009.

Groundwater plays a major role in social and economic development and in human and ecosystem health. However, little is known about the potential impacts of climate change on this resource in Canada, namely if groundwater recharge is increasing or decreasing over time. This paper focuses on trend statistical analysis of historical series of baseflow and groundwater levels and their field significance as indicators of recharge. Monitoring wells are mainly located in the southern half of western Canada, where few gauging stations either are available or provide significant trends. Both data sets are thus complementary. Results show that most available groundwater level series have significant trends (80%), whereas most available baseflow series have not (3%–33%). However, groundwater level series usually show smaller slope magnitudes than baseflow series. Mixed trends are often observed across Canada for a given variable, period, or series length, although some regions can have marked trends. For instance, ...

Numerical simulation of the radius of influence for landfill gas wells

In North America, most domestic waste produced is disposed in landfills. These sites generate leachate and gas, mainly CH 4 and CO 2 , which are harmful for the environment if not properly controlled. The design of active landfill gas recovery systems is based in large part on the radius of influence of vertical pumping wells. This parameter is commonly estimated empirically. This study presents results of numerical simulations of the radius of influence of gas recovery wells for different site conditions. The simulations were performed with the TOUGH2-LGM simulator. In the simulation scenarios, the radius of influence was defined in relation to several factors: the waste thickness, the generation rate of CH 4 gas in the waste, and CH 4 concentration in the recovered landfill gas. The results are presented in the form of general graphs that are not site-specific. The adequacy of the results still needs to be validated against field measurements. On the basis of simulation results, a systematic approach is proposed for the design of landfill gas recovery systems, and this approach is illustrated with a hypothetic example. This approach should guide landfill managers and engineers in the design of landfill gas recovery systems. The simulations only considered cases where landfills are open to the atmosphere, which are representative of most operating conditions. The results thus do not apply to post-closure conditions usually involving an impermeable cover built on top of the waste.

A watershed-scale study of climate change impacts on groundwater recharge (Annapolis Valley, Nova Scotia, Canada)

Abstract The potential impacts of future climate change on the evolution of groundwater recharge are examined at a local scale for a 546-km2 watershed in eastern Canada. Recharge is estimated using the infiltration model Hydrologic Evaluation of Landfill Performance (HELP), with inputs derived from five climate runs generated by a regional climate model in combination with the A2 greenhouse gas emissions scenario. The model runs project an increase in annual recharge over the 2041–2070 period. On a seasonal basis, however, a marked decrease in recharge during the summer and a marked increase during the winter are observed. The results suggest that increased evapotranspiration resulting from higher temperatures does not offset the large increase in winter infiltration. In terms of individual water budget components, clear differences are obtained for the different climate change scenarios. Monthly recharge values are also found to be quite variable, even for a given climate scenario. These findings are compared with results from two regional-scale studies. Editor D. Koutsoyiannis; Associate editor M. Besbes Citation Rivard, C., Paniconi, C., Vigneault, H., and Chaumont, D., 2014. A watershed-scale study of climate change impacts on groundwater recharge (Annapolis Valley, Nova Scotia, Canada). Hydrological Sciences Journal, 59 (8), 1437–1456. http://dx.doi.org/10.1080/02626667.2014.887203