Open Journal of Modern Hydrology, 2019, 9, 41-53 http://www.scirp.org/journal/ojmh ISSN Online: 2163-0496 ISSN Print: 2163-0461 DOI: 10.4236/ojmh.2019.92003 Apr. 18, 2019 41 Open Journal of Modern Hydrology End-Member Selection in Two-Component Isotope-Based Hydrograph Separation Samuel Bansah 1,2,3,4,5* , Jonathan Quaye-Ballard 6 , Samuel Andam-Akorful 6 , Edward Bam 7 , Geophrey K. Anornu 8 1 Department of Geological Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana 2 Isotope Hydrology Research Program (IHReP), Kumasi, Ghana 3 Department of Geological Sciences, University of Manitoba, Winnipeg, Canada 4 Manitoba’s Watershed Systems Research Program, Manitoba, Canada 5 Center for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada 6 Department of Geomatic Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana 7 Global Institute of Water Security, University of Saskatchewan, Saskatoon, Canada 8 Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana Abstract The science that underpins our knowledge and understanding of Isotope-Based Hydrograph separation (IHS) has gained grounds, over the last few decades, in the identification of streamflow sources. However, challenges still exist in identifying appropriate tracers and the right combination of end-members for the IHS process. In a two-component IHS analysis, the application of the dual isotopes tracers, δ 18 O and (or) δ 2 H, is regarded as the simplest method. We undertook an IHS study within a nested system of eight Prairie watersheds located in South central Manitoba, Canada. The work evaluated about 17,000 results emanating from the application of a combination of two potential tracers (δ 18 O and δ 2 H) and eight each of potential “old” and “new” water end-members in a two-component IHS process. The outcome showed occurrences of many mathematically possible but hydrologically unacceptable IHS results. The observation was particularly predominant within relatively larger perennial sub-catchments of the watershed. It is also shown that in- ter-site sub-catchment isotopic end-member transferability is possible within watersheds of similar physio-hydrographic characteristics. We suggest that a careful evaluation of the physio-hydrographic characteristics of catchments be considered in IHS studies in addition to the recommended guidelines in the selection of tracers and end-members. Keywords Hydrograph Separation, Oxygen-18, Deuterium, Stable Isotopes, How to cite this paper: Bansah, S., Quaye-Ballard, J., Andam-Akorful, S., Bam, E. and Anornu, G.K. (2019) End-Member Selec- tion in Two-Component Isotope-Based Hy- drograph Separation. Open Journal of Modern Hydrology, 9, 41-53. https://doi.org/10.4236/ojmh.2019.92003 Received: February 16, 2019 Accepted: April 15, 2019 Published: April 18, 2019 Copyright © 2019 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access