Time Lapse Hydrography

As part of the Spring Recession project, we have a set of study sites on rivers throughout the northern Sierra Nevada range in California. Part of this research includes monitoring the river's edge habitat with remote game cameras. After a year's worth of still image captures, we realized we could do some other processing with these images. This video shows images and hydrographs from two nearby rivers capturing the same moment in time. For each video, we pulled in river flow data from USGS flow gages at nearby, but not exact, locations.


Two sets of tools exist to create timelapse hydrographs. One uses Python and matplotlib, the other is based in R. Both create a hydrograph for each timepoint in the timelapse, overlay the hydrographs with images based on the timestamps, and finally pair the images together based upon closest timestamps (which also leads to the stuttering you see on the right side in the South Yuba below).  A number of open source programs are used in this process, including ImageMagick, exiftools, and Virtualdub or ffmpeg to create the videos at 10 FPS.

A github repository with all the R code used to make these Timelapse Hydrographs is here.

North Fork American and South Fork Yuba

The images in this video are taken by a pair of identical game camera's that take an hourly picture, on the hour, 24 hours a day. The left images are from the North Fork American River in the 1000-2000 foot elevation band. The images on the right are from the South Fork Yuba River, about 20 miles north of the first camera in the Sierra Nevada. The main difference we're interested in from these cameras is that the South Fork Yuba is regulated - it has a dam upstream controlling the flow of the river - while the North Fork American is not regulated in this area. You can see the differences in how the flows change. The South Fork Yuba changes flows rapidly as flows lower while the North Fork American drops more slowly. At high flows (storm events) the North Fork American changes more rapidly - a good signal - while the South Fork Yuba is buffered by the dam's controlled flow.

Clavey River and Tuolumne River Mainstem at Confluence with Clavey River

Similar to the North Fork American/South Fork Yuba video, these cameras are placed in order to cover two regions with similar precipitation patterns but with a different factor upstream. The left image shows just the Clavey River, an unregulated tributary to the Tuolumne River. The right image shows the Tuolumne River mainstem at its confluence with the Clavey river. The Tuolumne has a dam upstream.

This last video is similar to the previous one, but covers a longer time period and shows air temperature, water temperature, and flow on a combined graph overlaid across the frame.

Time Lapse Hydrography - Tuolumne and Clavey Rivers 2012 with Temperatures from Center for Watershed Sciences on Vimeo.