CVO staff and sediment specialists from USGS offices around the country led the Sediment Data Collection Techniques training course in Castle Rock, Washington. The week-long course was attended by 30 students representing the USGS, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, and the Nooksack and Klamath Tribes. The course provided participants with an understanding of basic fluvial-sediment concepts, sediment sampler characteristics, sampling protocol and techniques, laboratory analysis, surrogate technologies, and quality-assurance procedures. Field training exercises on the Cowlitz and North Fork Toutle Rivers gave students valuable hands-on experiences. Erosion of 1980 deposits at Mount St. Helens resulted in higher sediment loads in the Toutle and lower Cowlitz Rivers, decreasing the carrying capacity of channels, increasing flood risk, and affecting aquatic habitats. Sampling is a method of tracking the movement and volume of material moving downstream. For more information, see USGS Surface Water Information -- Fluvial Sediment, and Hazards from Post-Eruption Excess Sediment at Mount St. Helens.
Over the past half-century, great advances have been made in understanding debris flow behavior. Studies find that most debris flows originate on slopes that are steeper than 25 to 30 degrees and are mantled with low-cohesion soils and/or fragmented rocks that have become at least partially saturated by water. The resulting downslope flow can scour and erode a channel with devastating consequences for communities in its path. This new article describes the debris flow process from initiation to end, and provides guidance for assessing debris flow hazards. Read more at Debris flows: behaviour and hazard assessment.