Salt, streams & Selkirk students

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If you were tasked with finding the flow rate of a stream, would your initial thought be to use salt to do it?

Maybe not, but salt dilution gauging is actually one of the most accurate ways of measuring flow rates in creeks and streams. It is particularly useful in the steep mountainous streams that dominate the Kootenay region.

Paul Saso, a hydrologist with Living Lakes Canada, leads a hydrometric monitoring field lab with Selkirk College’s Integrated Environmental Planning students.

This was just one of the various flow measurement methods that Selkirk College’s Integrated Environmental Planning students recently gained hands-on experience in. Last month these students participated in a hydrometric monitoring field lab held at Anderson Creek near Nelson, B.C. The lab was led in part by Paul Saso, a hydrologist with Living Lakes Canada’s Kootenay Watershed Science (KWS) program.

In this triple focus lab, students learned to use three standard methods to gauge flow rate: salt dilution, the Mannings equation (an empirical equation for calculating flow rate using the channel velocity, flow area, and channel slope), and a standard current meter. The results between the three methods were compared and discussed.

The Mannings equation used by Selkirk College students to calculate stream flow.

During the portion of the lab dedicated to salt dilution gauging, students measured out an exact amount of salt in grams (accurate to two decimal places). This salt was then introduced into the creek at carefully chosen sites. As the salt was added into the creek, students waited downstream of these sites with a conductivity meter submerged in the water. The data about the water’s salt content from the meter was used to calculate how many liters of water were flowing down the creek per second.

“It was great to meet and learn with Paul. Being able to interact with my local stream and use state-of-the-art equipment was a highlight of the school term.” – Lori Clyde, Integrated Environmental Planning Student, Selkirk College

Being able to measure stream water flow with this level of accuracy can partially be attributed to the advanced technology in the KWS equipment arsenal. The conductivity meter used by KWS was developed by Fathom Scientific and generously donated to the KWS program. This conductivity meter, with the endearing official name the “QiQuac”, allows the KWS team to have greater confidence in the data that the program produces.

“It was so great that we got to use the latest technology and learn from someone as knowledgeable as Paul Saso… Seeing the salt dilution method of stream discharge measurement in the field was a great learning experience.” – Tyson Leonard, Integrated Environmental Planning Student, Selkirk College

Why is this data important?

Understanding stream flow (i.e., the volume and speed of moving water) is important for many reasons. It’s a critical consideration if you’re planning to build a house by a water source and trying to ascertain the flood risks. Municipal governments also rely on this information when making water licensing designations. Decision makers must consider downstream ecosystems and fish populations, and maintaining a flow of water that sustains these systems, when determining how many individuals may be licensed to use a water source.

Students participating in a hydrometric monitoring lab facilitated in part by Paul Saso, pictured in center. Left to right: Nathan Bertolucci, Mac Puddu, Paul Saso, Anna Heiter, Lori Clyde

Living Lakes Canada hopes to see the students involved in the Integrated Environmental Planning program at Selkirk College continue on to provide effective water monitoring support to their communities using the new flow measurement techniques they have learned.

“Engaging with younger generations of environmental scientists is a highly rewarding aspect of my work. Passing on my knowledge and experience to students and seeing their enthusiasm for the field is wonderful. Thank you to our generous funders for helping KWS empower these budding scientists on their path to maintaining healthy and safe watersheds.” – Paul Saso, Hydrologist, Living Lakes Canada’s Kootenay Watershed Science program

Still curious about salt dilution gauging? Want to learn more? Follow the link for a more detailed explanation of the principles behind the process! Kootenay Watershed Science Program Page

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