Integration of sediment fingerprinting techniques and sampling approaches within a prairie watershed in southern Alberta

Abstract

Soil erosion can cause sedimentation and eutrophication of waterbodies, which can decrease the quality of water. This study took place in southern Alberta within the Lower Little Bow River (LLBR) watershed, which has been a source of water quality studies as a part of the Oldman River Basin Water Quality Initiative. The objectives of this study were, firstly, to identify and apportion sources of suspended sediment using a sediment fingerprinting technique and the mixing model, MixSIAR, within a small 6-km reach of the LLBR, secondly, to build a better understanding of colour properties as tracers, and thirdly, to explore the effect of reach sampling within using the MixSIAR model. The first objective was accomplished through the sampling of multiple watershed sources including Agricultural Land, Coulee Walls, Stream Banks, an Irrigation Return-Flow channel and Upstream sediment. Suspended sediment was collected within the reach itself and un-mixed to determine source proportions contributed by each of the five potential sediment sources. The second objective was accomplished by taking three approaches in order to determine the appropriate environmental tracer combination to apportion sources accurately and how these affect choosing appropriate environmental tracers for sediment fingerprinting. The third objective of this thesis was accomplished by determining the composition and incorporation of upstream inflowing sediment into a watershed reach when conducting a sediment fingerprinting study. The mixing model, MixSIAR, was used as a tool to manipulate the watershed in order to determine how to improve the efficiency of the sediment fingerprinting process regarding tracer selection and sampling approaches. The MixSIAR model is used as a tool to determine how to design an approach to a reach within a watershed and the significance of upstream inflowing sediment inclusion as a sediment source.