Estimating Bulk Density in Vertically Exposed Stoney Alluvium Using a Modified Excavation Method

Abstract

Despite many decades of education and refining land-use practices, accelerated stream bank erosion is still prevalent in the United States. Eroding stream banks produce a sediment load to the riverine system and can cause reduced water quality as a result of increased suspended sediment. As total maximum daily loads (TMDLs) for water bodies impaired by turbidity or suspended sediments become more numerous, a simple, in situ field technique will be needed to estimate the bulk density of readily erodible stream bank material so that reasonably accurate sediment loading rates can be estimated. In this study, the excavation/polyurethane-foam technique for estimating total bulk density was applied to vertically exposed alluvium with high coarse-fragment content. Though not previously attempted in vertically exposed alluvium with high coarse-fragment content, the excavation/polyurethane-foam technique appears to provide a reasonably accurate estimate of the total and soil (<2-mm size fraction) bulk density from vertically exposed, alluvial deposits with high coarse-fragment content (i.e., >70%) along eroding stream banks. Obtaining bulk density estimates using this method would facilitate calculation of sediment loading rates to riverine systems with actual field data.

Characterization and Estimation of Hydraulic Properties in an Alluvial Gravel Vadose Zone

“…The mean bulk density from the 17 sandy gravel samples within the trench was 2.20 g/cm 3 (range 2.00–2.32 g/cm 3 ), giving an average calculated porosity of 17% (range 13–25%). The average calculated bulk density of the sandy gravel fine fraction (<2 mm) was 1.26 g/cm 3 (range 0.81–1.57, σ = 0.21), similar to 1.3 g/cm 3 reported by Brye et al (2004) in stony alluvium, although greater than values calculated in stony soils by Sauer and Logsdon (2002) This leads to an estimate for the average calculated porosity of the fine (or non‐gravel) fraction of 53% (range 41–70%). These bulk density and porosity values probably reflect a combination of spatially variable macroporosity, the sand–silt matrix material actual bulk density, and a potential error in volume estimation from the volume replacement method.…”

“…Samples of each of the main three textures were collected at Lowcliffe and Burnham and analyzed for PSD and water content. In addition, the bulk density of the open‐framework lenses was determined from the cliff faces using an expanding foam method (Brye et al, 2004). Using this method, the open‐framework lenses were excavated carefully by hand and expanding foam was injected into the subsequent cavity, completely filling it.…”

Wolf‐triggered trophic cascades and stream channel dynamics in Olympic National Park: a comment on East et al. (2017)

“…During our 2005 and 2006 field study we noted that vertical eroding banks were common along the Hoh, Queets, and Quinault Rivers (Figure 2; see also Beschta and Ripple, 2008), thus making significant volumes of sediment locally available to river channels. For example, each 1-m increase in active channel width from fluvial erosion that removes a river bank 2-m in height (bulk density of~2 g cm À3 ; Brye et al, 2004) represents a local addition of 4000 tonnes of sediment per kilometer of river length, as well as appreciable volumes of large wood. East et al (2017) essentially ignore any effects of near-channel sources of sediment in their study reaches as a potential mechanism for augmenting ongoing increases in channel widths and braiding.…”

Factors influencing the formation of shallow landslides in the Boston Mountains of northwest Arkansas, USA

“…Similar to methods used previously for soil sampling in the region (Brye, Morris, Miller, Formica, & Van Eps, 2004;Brye & West, 2005), soil samples were oven-dried at 70°C for 48 h and manually disaggregated with a mortar and pestle. Samples were then analyzed for particle-size distribution using a modified hydrometer method (Gee & Bauder, 1979).…”