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Stream Solute Tracers


Problem Statement

Solute tracers are used to estimate stream discharge and assess transport and transformation in streams, commonly to infer transport into temporary storage zones including in-channel dead zones and hyporheic zones. The planning, execution, and interpretatation of these tracers is not a common skill in undergraduate hydrology and hydraulics courses, but the rich data that result make these a useful tool.

Module Overview

This module covers the required background knowledge to plan, execute, and interpret stream solute tracer studies.

Topics Covered

Solute tracer study design, estiamtion of discharge by dilution gauging, estimation of advective and dispersive processes, inference of gross gains and losses along a study reach, calculation of summary metrics to describe short-term storage, and a brief introduction to StorAge Selection as an approach to study streams


Students will benefit from an introductory knowledge stream hydraulics, though it is not required. Calculations in the assignments require students to hav esome skill in computations. Students have been successful in this course using spreadsheets, R, Matlab, and Python.

Learning Objectives

The overarching goal of this course is to enable students to design, execute, and interpret stream solute tracer studies. Upon completion of this module, students will be able to: (1) Design both slug and constant rate injections; (2) Quantify discharge, advective velocity, and dispersion based on field data; (3) Quantify and characterize transport and transformation in a study system using techniques including Short-term storage analysis, temporal moments, channel water balance, breakthrough curve decomposition, StorAge Selection functions; (4) Quantify and characterize transport and transformation in a study system using channel water balance and network turnover; and (5) Demonstrate a conceptual understanding of the strengths and weaknesses of each analysis and study design, and how they complement one another, in analysis of stream solute tracer data.

This will be accomplished through activities within each section. Results from each activity will be recorded in specified results templates. The results templates for each activity can be found at the beginning of each activity. The results templates are organized such that results from one activity can easily be used in successive activities.

Course Authors

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Adam S. Ward

Ward is a hydrologist who uses stream solute tracers to study transport and transformation in systems that couple water in streams to less mobile domains including in-channel dead zones and hyporheic zones. He is an expert in the use and interpretation of stream solute tracers, and this course content is based on a series of short courses he has instructed over several years. Students or instructors seeking support should contact Ward at

Target Audience

The target audience for this module is anyone seeking to plan and execuate a solute tracer study in a stream or river.

Tools Needed

Students will need to have access to a computational tool of their choice. Spreadsheets are sufficient, though the advanced user will benefit from a tool like R, Python, or similar

Expected Effort

This course contains five primary sections. It would be appropriate to cover one section per week in terms of pacing. Each section includes reading and lecture-based content that should take users 2-4 hours of time to read or watch, and homework assignments that should take another 4-6 hours each week.

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