Joel Cahoon

Assessment of Trout Passage through Culverts in a Large Montana Drainage during Summer Low Flow

Abstract We used a combination of methods to assess the degree of fish passage restriction from road culverts during summer low flow for westslope cutthroat trout Oncorhynchus clarkii lewisi and brook trout Salvelinus fontinalis across a large drainage basin. The FishXing fish passage model classified 41 of 45 (91%) culverts as barriers to upstream passage for 152-mm westslope cutthroat trout. Population sampling upstream and downstream of 23 culverts revealed little differences in westslope cutthroat trout or brook trout above and below culverts, although density declined upstream when culvert slopes exceeded 4.5% and outlet drops exceeded 20 cm. A passage experiment with marked trout at 12 culverts showed that the proportion of upstream movement averaged 2.45 times lower through culverts (mean, 0.37) than through natural stream reaches (mean, 0.63; χ2 = 26.2, P < 0.001). Outlet drop was the most important factor affecting passage success; probability of passage was low for small trout (<100 mm fork leng...

A microbiologically clean strategy for access to the Whillans Ice Stream subglacial environment

Abstract The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project will test the overarching hypothesis that an active hydrological system exists beneath a West Antarctic ice stream that exerts a major control on ice dynamics, and the metabolic and phylogenetic diversity of the microbial community in subglacial water and sediment. WISSARD will explore Subglacial Lake Whillans (SLW, unofficial name) and its outflow toward the grounding line where it is thought to enter the Ross Ice Shelf seawater cavity. Introducing microbial contamination to the subglacial environment during drilling operations could compromise environmental stewardship and the science objectives of the project, consequently we developed a set of tools and procedures to directly address these issues. WISSARD hot water drilling efforts will include a custom water treatment system designed to remove micron and sub-micron sized particles (biotic and abiotic), irradiate the drilling water with germicidal ultraviolet (UV) radiation, and pasteurize the water to reduce the viability of persisting microbial contamination. Our clean access protocols also include methods to reduce microbial contamination on the surfaces of cables/hoses and down-borehole equipment using germicidal UV exposure and chemical disinfection. This paper presents experimental data showing that our protocols will meet expectations established by international agreement between participating Antarctic nations.

SEDIMENTOLOGICAL ANALYSES OF EGGSHELL TRANSPORT AND DEPOSITION: IMPLICATION AND APPLICATION TO EGGSHELL TAPHONOMY

Abstract The interpretation of fossil eggshells can be problematic because eggshells may be transported by hydraulic flow in floodplains, making it difficult to interpret the reproductive behavior and ecology of parent animals. A series of flume studies was conducted to establish analytical techniques for assessing eggshell hydraulic transport in the fossil record. We investigated preferred eggshell orientation after transport, the relationship of flow competence with eggshell height and volume, and the size of clastic sediment expected to be associated with transported eggshells. Goose, emu, and ostrich eggshell fragments were released in a flume with decelerating flow. The transport of each eggshell was observed five times on each of four substrates (coarse sand, sparse gravel, dense gravel, and polyvinyl chloride). At eggshell deposition, eggshell orientation and flow depths were recorded. Critical bed shear stress for eggshell deposition was estimated based on the flow depth at the point of eggshell deposition, tested relative to eggshell height and volume, and used to estimate the size of hydraulically equivalent particles. The probability of concave-down orientation after transport was > 85% regardless of eggshell type or substrate. The bed shear stress at eggshell deposition reflected the eggshell height and volume. The estimated size of hydraulically equivalent particles was coarse sand or larger. A high proportion of concave-down eggshells in a fossil assemblage may indicate transport. In addition, eggshells may be sorted according to their height and volume. Coarse sand or larger particles observed in a matrix of fossil eggshells may suggest eggshell transport.

Flow in Conduits

Publisher Summary This chapter provides an overview on hydraulics. The analysis of water flow in closed and open conduits depends on three fundamental principles such as the conservation of mass, energy, and momentum. Each principle is considered in terms of the equation(s) derived from its application. The first well-known formula for flow in pipes is proposed by deChezy. Another formula, the Hazen–Williams (H–W) formula, is widely used in the United States. The most common equation used in the United States for open channel flow is the Manning equation. The most universal (and one of the quickest) means for solving open channel flow with or without the Escritt modification are found in a user-friendly program, UnifCrit2.2 developed by Cahoon. UnifCrit2.2 solves the Manning equation either unmodified (Escritt=0 in the program) or modified by the use of Rm (Escritt=1) in round pipes. This versatile program also solves for critical velocity, depth, and flow in both round and trapezoidal conduits. Computational fluid dynamics is a powerful method for predicting fluid motion in a continuum by using numerical techniques. The Navier–Stokes equations governing fluid motion are valid at all points but, as it is not feasible to calculate flow characteristics at every point, the equations are solved at a finite number of points called “nodes.”

Pumps: Intake Design, Selection, and Installation

Publisher Summary This chapter deals with wet well design, pump piping, and selection of pumping equipment. The pump intake design must satisfy several requirements for proper approach conditions by avoiding poor velocity distribution at the entrance to the pump, excessive swirling in the pump intake piping, air entrainment in the pumped flow, unstable approach conditions in multiple pump operation, and vortices. Model studies are useful for finding and correcting faults in the hydraulic flow patterns in wet wells. The ANSI/HI 9.8-1998 standard requires a physical model study if the sump or piping geometry differs from the standard, the approach flow is non-uniform or unsymmetrical, and the flow rate is more than 2520 L/s (40,000 gal/min) per pump or the total flow exceeds 6310 L/s (100,000 gal/min) with all pumps running. Several factors that need to be considered during pipe selection include quality of the fluid to be pumped, required design capacity (initial minimum, average, and maximum flow rates), operating conditions (best-case and worst-case system head curves, maximum and minimum flow rates, submergence, and/or NPSH). A step-by-step procedure for selecting pumps involves developing the calculations for the performance requirements completely and on the basis of the best- and worst-case assumptions for system dynamic headlosses, specifying materials that are suitable for the application, specifying the proper balance grade number, and deciding the number of pumps to be used and the type of pump.

Swimming Capabilities of Arctic Grayling

Abstract A native population of arctic grayling (Thymallus arcticus) exists in the upper Missouri River drainage of Montana. While formerly abundant, agricultural practices, predation, angling pressure, barriers to mobility, and competition from other species appear to be the causes of decreased presence of artic grayling in the Northwest (Skaar 1989). The purpose of this study was to augment the information base of the swimming ability of arctic grayling and to examine the effect of repeated trials using the same fish. Forty hatchery-raised grayling were separated into two cohorts and reared in an artificial stream. The mean fork length of all fish was 290 mm (SD ± 16). Cohort 1 was tested in a swim chamber experiment once per week for three consecutive weeks. Cohort 2 was tested only once in the swim chamber sixteen weeks later. Each fish was tested by placing it in the chamber initially operating at a low water velocity (30.5 cm s-1) and then regularly increasing the velocity until the fish rested on the screen at the downstream end of the chamber. The maximum water velocity against which each fish held its position was observed, and is reported as the sprint speed (Usprint). Overall the mean Usprint observed was 5.64 BL (body length) s-1 (SD ± 0.78) equal to an absolute velocity of 1.66 m s-1 (SD ± 0.19). Cohort 1 had a mean Usprint of 5.40 BL s-1 (1.62 m s-1) and Cohort 2 had a mean Usprint of 6.33 BL s-1 (1.77 m s-1). There were significant differences, and a generally increasing trend, in Usprint between the successive trials using Cohort 1.