Water Quality Through the Lens of a Trail Camera

Photos provide the unique opportunity to extract both qualitative and quantitative hydrological data from one image. Our goal is to use a camera trap configured to take color photos at 15 minute intervals during daytime hours to assess sediment movement through a stream by analyzing the RGB color bands and how they fluctuate through time. Data was collected from October 2023 to April 2024 in lower Dry Creek Watershed, which lies 16 km NE of Boise and was established in 1999. It is 28 km^2 in area and consists of grasses and shrubs at low elevations and coniferous forests at higher elevations. Precipitation is rain dominated at low elevations and snow dominated at high elevations. This is a perennial creek with one perennial tributary: Shingle Creek. The headwaters sit at an elevation of 2100m and drainage is at 1000m. Data was obtained in 15 minute intervals from both the trail camera and complimentary light and temperature sensors. One light and temperature sensor was located in the stream and one out of the stream, while the camera was secured to a tree to take images of the stream from above. After pulling the RGB color bands from each image collected, the values were organized into a time series and compared to plotted fluctuations in the light and temperature data. We hypothesized that distinctive and outlying changes in the light and temperature data are representative of sediment movement and these changes will coordinate with changes in the RGB color bands, indicating that RGB information itself can capture temporal dynamics of sediment transport like the passing of sediment pulses. As we continue to collect data, we are noticing trends of the RGB color bands showing distinctive changes coinciding with sediment transport. Due to differences in mechanism and type of sediment though, these changes are not always constant. With more data, we expect to narrow this change down and better determine the relationship between transport and image analysis. With more effective and refined methods for data processing, photo hydrology represents a potentially economical and innovative tool for advancing coupled hydrologic, geomorphic and ecological understanding.