ABSTRACT:

Width changes along the Saxtons and White Rivers (VT, USA) during Tropical Storm Irene as presented in Buraas, E.M., Renshaw, C.E., Magilligan, F.J., Dade, W.B., (2014) Impact of reach geometry on stream channel sensitivity to extreme floods, Earth Surf. Process. Landforms 39, 1778-1789.

ABSTRACT:

Yearly pebble count data along Vermont rivers pre and post Tropical storm Irene

ABSTRACT:

Fractured rock permeability can increase by crack extension that creates additional flow pathways or by increases in crack openings that increase crack transmissivity. Understanding the partitioning between these two mechanisms during rock deformation is critical for conceptual models of fluid flow and transport in crystalline rocks and sedimentary layers with low matrix permeability and for the hydromechanics of crustal rocks. Using ice as a model for rock, new systematic experiments reveal that when subject to uniaxial loading at a constant strain rate, crack density remains nearly constant after the onset of percolation even while permeability increases, indicating that after the onset of percolation the increase in permeability is primarily due to the opening of existing cracks rather than the extension of cracks. These observations have implications for conceptual models of fractured rock permeability which often focus on the evolution of permeability with changing fracture density rather than changing fracture transmissivity and for attempts to link fractured rock permeability to seismic properties which often dominantly consider changes in crack density rather than crack apertures.

Data include summary of loading curves, elastic properties and permeabilities of crack networks created in uniaxially compressed freshwater ice

ABSTRACT:

Using ice as a model for rock, we experimentally test the prediction of percolation theory that for a sufficiently large sample, the onset of percolation is isotropic even when the crack network is anisotropic. Consistent with theory, experimentally we find that in strongly anisotropic crack networks induced by uniaxial loading at a sufficiently high strain rate, the onset of percolation is nearly isotropic in samples where the dimension of the sample is about an order of magnitude greater than the length of the largest crack. The onset of percolation is isotropic even though nearly 90% of the induced cracks are oriented within about 10° of the direction of applied compression.

ABSTRACT:

We combine measurements of the fallout radionuclides 7Be and 210Pb and the stable isotopes of hydrogen in water with a conceptual model of suspended sediment trapping by channel margins to quantify suspended sediment mobilization and storage in a stream and its channel margins during individual intermediate-sized storm events with recurrence intervals of a few months or less. We found that across all events the channel bed was a source of organic-rich suspended sediment and the channel margins a sink and observed strong seasonal variations in the export of suspended sediment. The increasing export of suspended sediment through the spring and summer may result from the in-channel decomposition of organic debris as indicated by its changing bulk δ13C composition and changing relationship between turbidity and suspended sediment concentration. The trapping of suspended sediment limits the transport distance of suspended sediment, which, given sufficient discharge to fully suspend the sediment, is nearly independent of stream discharge for sub-bankfull discharges. An analysis based on hydraulic geometry scaling is consistent with empirical observations that the characteristic transport length decreases with increasing watershed area. Simultaneously, limited available data indicate that the fractional size of the channel margins where deposition occurs decreases with increasing watershed area. The increasing transport length and decreasing fractional margin area results in a systematic decoupling of the channel from terrestrial organic matter inputs.

ABSTRACT:

Channel and tracer data for "Impacts of Channel Reach Morphology and Seasonal Flow History on Bedload Particle Mobility and Transport Efficiency"
by Rossi et al.

Tab Description
Morphology Channel elevation (relative to arbitrary datem) and reach morphology as function of distance downstream
Hydrograph Hydrograph derived from merging of area-scaled discharge from nearby USGS gage and, once installed, from local stage gage
active tracers Location, Shields and dimensionless stream power values for each recorded movement of active tracers
passive tracers Surveyed locations, reach morphologies, and virtual velocities of passive tracers