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Using stable isotopes to develop a regional hydrogeological model and characterize nitrate sources in groundwater

dc.contributor.advisorWassenaar, Lenen_US
dc.contributor.advisorHendry, M. Jimen_US
dc.contributor.committeeMemberKnight, Dianeen_US
dc.contributor.committeeMemberBarbour, S. L.en_US
dc.contributor.committeeMemberAnsdell, Kevinen_US
dc.creatorAthanasopoulos, Panagiotaen_US 2009en_US
dc.description.abstractSemi-arid regions, like the Okanagan Basin of British Columbia, Canada, are often faced with the difficulty of managing limited groundwater and surface water resources while accommodating rapid population growth and increasing land development. In the South Okanagan Basin, a better understanding of groundwater recharge sources, groundwater availability and susceptibility of water supplies to anthropogenic contamination is needed to best direct and protect the region’s water resources. The purpose of this study was: (1) to characterize the regional hydrogeological setting of the South Okanagan Basin by establishing an isotopic and geochemical framework that included precipitation and surface waters of the Okanagan Basin and groundwaters of the South Okanagan Basin; and (2) to characterize nitrate contamination and its sources in shallow groundwaters of the Osoyoos area. Stable isotopes of water, nitrate and dissolved oxygen, groundwater chemistry, water levels and enriched tritium, tritium/helium and/or radiocarbon age dating techniques were used. Two provisional local meteoric water lines were established for the Okanagan Basin: ẟ²H=6.06ẟ¹⁸O–31.21 (Osoyoos) and ẟ²H=7.03ẟ¹⁸O-12.68 (West Kelowna). Surface waters of the Okanagan River system were sources of irrigation water in the South Okanagan Basin valley and irrigation-return flow was the primary source of recharge for shallow groundwaters. Fractured bedrock in highlands east and west of the valley were not a significant source of recharge for shallow valley groundwater, however, may recharge deeper, or basal, valley deposits. As irrigation-return flow controls shallow groundwater dynamics in the valley sediments, groundwater quality is susceptible to anthropogenic contamination. In Osoyoos, nitrate was present in shallow groundwaters at concentrations of up to 24.4 mg/l N as a result of fertilizer nitrogen applied at the soil surface, mostly at orchards. Two agricultural drainage systems in north Osoyoos discharge roughly 1,900 kg N/year from nitrate-contaminated groundwater directly into Osoyoos Lake and may contribute in part to its eutrophication.en_US
dc.subjectRegional Hydrogeologyen_US
dc.subjectAgricultural Drainageen_US
dc.subjectSurface Wateren_US
dc.titleUsing stable isotopes to develop a regional hydrogeological model and characterize nitrate sources in groundwateren_US
dc.type.materialtexten_US Sciencesen_US Sciencesen_US of Saskatchewanen_US of Science (M.Sc.)en_US


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