The Use of Temperature and Environmental Isotopes as Tools to Characterize Groundwater Discharge to the Grand River, Ontario, Canada

Geochemistry;Hydrology;Isotopes;Hydrogeology;Earth Sciences

Westberg, Robert Eric

University of Waterloo

关键词: Geochemistry;    Hydrology;    Isotopes;    Hydrogeology;    Earth Sciences;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/7280/1/Westberg_Robert.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

The Grand River Watershed, in southern Ontario, is home to approximately 900,000 people and oneof the fastest growing regions in Canada; specifically, in the urban areas of Guelph, Cambridge,Kitchener, and Waterloo. This growth strains the watershed’s capacity to supply adequate waterresources to these municipalities, as well as manage the waste-water treatment effluent dischargedfrom them. Nowhere in the watershed is this juxtaposition in water resource function more apparentthan at the city of Brantford, with a population of approximately 100,000 people. Located forty-twokilometers downstream from the major urban areas, Brantford is unique in the watershed in that itobtains its entire municipal water supply directly from the Grand River, into which the upstreammunicipalities discharge 77% of the total waste-water treatment plant effluent emitted to thewatershed. One contaminant of concern is nitrate, which, for decades, has been linked to numeroushuman and aquatic health complications. The input of nitrate from these upstream WWTP’s isconsiderable; the WWTP’s have a combined flow rate of 2.3 m3s-1, and a mean nitrate concentrationof 10.4 mg N·L-1 (data from Anderson, 2012). As a comparison, the Nith River, the largest tributaryto the Grand River between Cambridge and Brantford, has a summer baseflow of 2.9 m3s-1 and, from2000 to 2004, had a mean nitrate concentration of 4.4 mg N·L-1 (Cooke, 2006).Brantford, in addition to treating their water supply, relies on the dilution of in-stream nitrate fromgroundwater that is thought to discharge along the Grand between Cambridge and the Brantfordmunicipal water intake. This 40-km reach of the Grand River is colloquially referred to as either thedischarge reach or the recovery reach. Recent data from various authors indicate that groundwatermay not always act to dilute in-stream nitrate from upstream WWTPs (Encalata, 2008; Pastora, 2009;Rosamond 2009).The main objective of the research completed in this thesis was to refine the conceptual model ofgroundwater/surface water interaction along the Grand River between Cambridge and Brantford.Refinement of this conceptual model was accomplished in two parts. First, groundwater discharge,from bank seepage and direct discharge through the riverbed, was located using a variety of methods;a simple reconnaissance survey by canoe, a FLIR thermography survey, drag probe surveys, and atemperature profiling method. Then domestic wells, seeps, tributaries, riverbed discharge, andWWTP effluent were sampled to geochemically characterize inputs to the Grand River.