For this Science Friday we are going to dive a little bit deeper into streamflow on the Rattlesnake Creek. We explore what a typical discharge rate looks like and how it will change with the pressing impacts of climate change.
The map included in this post is highlighting an analysis conducted on parts of the country where streamflow is strongly influenced by snowmelt. You can see that Montana fits into the analysis area. This map is showing the changes in the timing of annual high winter-spring runoff carried by rivers and streams from 1940 to 2018 (so a few years back but still a good representation of what increase of snowmelt can look like) (1).
Now let us zoom in a lot, all the way to the Rattlesnake Creek. By accessing the DNRC stream gauge data, we can see what the discharge has been over the past few years (2020-2022).The first graph is showing, alone, the discharge rate. The second graph shows how temperature fluctuates with changing discharge rates (2).
Streamflow naturally varies over the course of a year. High-flow periods typically occur in the spring as the snow melts, and then the lowest flow periods run into the summer (as represented in the graphs). The amount of streamflow is important because very high flows can cause erosion and damaging floods, while very low flows can diminish water quality, harm fish, and reduce the amount of water availability for people to use (1).
The timing of high flow periods is important because it affects the ability of a watershed to preserve and hold some of the water from these high-flows. Migratory species are also impacted by this, as they depend on particular patterns of stream flow as part of their life cycle (1).
Climate change affects streamflow by changing the amount of spring snowpack, and air temps that influence the size and timing of high flow periods. More precipitation also will likely cause higher stream flows. And droughts, as they become more frequent and severe, could have the possibility of reducing stream flow in certain areas (1).
Right now we are seeing the high discharge rates happening earlier and earlier on the Rattlesnake Creek and surrounding rivers. It is important to keep an eye on these gauges and continue monitoring to try to find ideas or solutions that will make our communities more resilient to the pressing impacts of climate change and how it will affect our Montana Waters.
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