Conference Papers

Measuring changes in the elevation distribution of sub-aerial fine ( 2 mm ) sediment and estimating sandbar volume multiple times per year can improve sediment budget calculations in fluvial systems. In the Grand Canyon of the Colorado River, effects of dam operations on sandbar size and distribution is of long-term management interest. Bar-building controlled floods have been...

Bullseye Snakehead Channa marulius (Hamilton 1822) was first detected in the southern Florida town of Tamarac in 2000 and has been expanding its geographic range since. Environmental DNA (eDNA) analysis is a newly-developed technique used to noninvasively detect cryptic or low-density species or those that are logistically difficult-to-study. Genetic material shed into the environment...

The dynamics of slow landslide motion can predispose oversteepened and extended slide regions to debris-flow initiation. For more than 20 years, our real-time monitoring, combined with repeat high-precision GPS surveys, of the Cleveland Corral landslide complex, California, USA, reveals that debris flows initiate from slow-moving kinematic elements of this complex. Different slide...

Since water-year (WY) 2011, pool levels at Fall Creek Lake, Oregon, are temporarily lowered to an elevation near historical streambed each fall, creating free-flowing channel conditions that facilitate downstream passage of juvenile spring Chinook salmon. These drawdown operations have also mobilized substantial quantities of predominantly fine (

The worldwide network of unpaved roads is estimated to include at least 14 million km (8.7 million miles; 1). Although they are vital for local communities, these roads are expensive to maintain and may cause environmental damage through sediment and dust pollution (e.g., 2). Among aggregate-surfaced roads, locally available materials are often used as a surface wearing course, with...

Debris-flow experiments and models commonly use “hot-start” initial conditions in which downslope motion begins when a large force imbalance is abruptly imposed. By contrast, initiation of natural debris flows almost invariably results from small perturbations of static force balances that apply to debris masses poised in steep channels or on steep slopes. Models that neglect these...

Cretaceous-Paleocene porphyry Cu(±Mo±Au) occurrences are scattered throughout the Yukon-Tanana upland in eastern Alaska. Known occurrences in eastern Alaska are poorly characterized, despite a resurgence in exploration. Porphyry deposits in the upland are emplaced into structurally complex metamorphic rocks representing a variety of tectonic environments, resulting in diverse alteration...

This presentation summarizes the proposed updates to earthquake design ground motions for the 2020 edition of the NEHRP Recommended Seismic Provisions, expected to be incorporated into the ASCE 7-22 Standard. The implications of these updates on the values of design ground motions for example locations in both conterminous and nonconterminous U.S. cities are shown and discussed.

The introduction of snakeheads from their origins in Asia is relatively recent to the conterminous United States with the first of many collections beginning in the late 1990s. For decades they have been commercially fished and aquacultured around the world for human food and, to a lesser degree, for the aquarium trade. Over a dozen snakehead species known to be of economic importance...

Northern Snakehead Channa argus weighing 188.54+13.80 g were fed live Oriental Weatherfish Misgurnus anguillicaudatus at five rations (starvation, 1, 2, 4% body weight per day and satiation) at 28 oC under laboratory conditions to determine its growth and energy budget in relation to ration. The specific growth rate increased linearly with increasing ration and food conversion...

The orogenic gold veins of Grass Valley, California, USA, compose the historically richest lode gold district in the North American Cordillera. Petrographically, the veins exhibit a range of primary textural relationships allowing the reconstruction of the paragenetic sequence of mineral formation. Two generations of quartz are distinguished by optical cathodoluminescence microscopy and...

The paragenesis, textures, and chemical compositions of secondary hematite in regional potassic altered rhyolites, four IOA deposits, the sedimentary iron deposit at Pilot Knob and the Boss IOCG deposit in SE Missouri were determined and compared to primary magnetite from the IOA and IOCG deposits. Magnetite is composed of elements characteristics of mafic to intermediate intrusions...