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The connectivity of river drainages has been decreased by the installation of roadway culverts, particularly for the salmonids of the Pacific Northwest. Thousands of culverts within the State of Washington have been designated by the state DOT as fish passage barriers. Though it is well known that the anadromous salmon travel upstream to spawn, recent evidence suggests that juvenile salmon also travel upstream to seek preferred habitats for feeding, which may ultimately improve their survival at sea. Retrofitting culverts is an economical solution that has been initially implemented to improve adult salmon passage. Baffles increase water depth for low flow conditions and reduce velocities for higher flowrates. To determine the effect of baffles on upstream passage of juveniles, sloped-baffles were studied at a culvert test bed near Tenino, Washington. Using an Acoustic Doppler Velocimeter (ADV), 3-D velocity fields were collected in a full-sized 12.2 m (40’) long, 1.8 m (6’) diameter corrugated culvert. The culvert slope, baffle spacing, and baffle height were varied to observe flow regime trends that describe conditions suitable for fish passage. This project is unique from other hydraulic studies in that biological testing was conducted in conjunction with the hydrodynamic measurements. Biologists randomly selected 100 juvenile Coho salmon from the on-site rearing facility and allowed the fish to ascend the culvert during a three hour period. The movement of the fish was recorded with video cameras and the passage rate was determined.Results indicate that there is considerable spatial variability in the flow created by the baffles within the culvert. The flow is asymmetric, consisting of a jet traveling over the low side of the baffle and an area of re-circulating water on the high side of the baffle. The asymmetry decreases as the discharge increases and the mean water height surpasses the baffle height. The diversity of flow structures created by this asymmetry is important because it increases the number of reduced velocity paths that fish may travel. The fish passage success rates are also consistent with the trends of asymmetry: as the culvert discharge increases fish are limited to fewer possible paths, and passage rates decrease. The results suggest that both the structure of the flow and the average speed of the flow affect the passage rate. We present a scaling equation that relates the occurrence of flow structures to the independent study parameters in order to provide guidance in baffle implementation. Recommendations for future work include further biological interpretation and testing, so that the hydraulic and biological results may be more closely coupled.

Low-head dams are built across rivers to raise upstream water levels enough for diversions for beneficial use or to reduce stream channel incision. There are untold thousands of these structures in the United States; many are well over a hundred years old. Although the structures are not high (3 - 20-ft), a condition known as a submerged hydraulic jump or 'hydraulic' can develop downstream that produces a reverse current. Any person who passes over the dam during such a condition will very likely drown. More than 1,000 fatalities have occurred at low-head dams in the United States. These dams are often "nonjurisdictional," meaning that they are not part of any state or federal dam safety and inspection program. Any low-head dams that are part of dam safety programs are typically considered "low hazard" and are therefore not a focus of these programs. Often the ownership cannot be easily determined, and in many cases the low-head dam is either abandoned or no longer serving its purpose. State Dam Safety Regulatory programs in the United States, which have traditionally focused on preventing loss of life and property damage resulting from dam failures, are increasingly concerned about public safety and the risk of fatalities at low-head dams. We recommend that states enact legislation specifically addressing low-head dams and suggest considering the approach taken by the state of Indiana that (1) defines low-head dams, (2) requires a statewide inventory of low-head dams and owners, (3) sets warning standards, (4) publishes information on low-head dam safety, (5) furnishes information to owners on low-head dam removal and modification, (6) requires notification to the state of changes in ownership, (7) restricts persons from accessing low-head dams, and (8) declares state immunity for those dams not owned by the state. Other elements may also be useful, such as increasing the penalties for noncompliance or deeming landowners to have met the duty of care for warning the public of the hazards posed by the dam. For all low-head dam owners we recommend posting and maintaining adequate warning signs to help reduce the number of recreationists passing over low-head dams. [ABSTRACT FROM AUTHOR]

The hydrodynamic flow field in streams and rivers influences many ecological processes including organism dispersal, habitat use, and resource acquisition. Understanding the linkages between hydrodynamic and ecological processes is essential for developing effective restoration and management tools. Despite the pervasive influence of flow velocity and turbulence, the details of natural stream flow fields as they apply to ecological concepts are poorly understood. In this study, velocity and turbulence distributions were investigated at two spatial scales using an acoustic Doppler velocimeter. The measurements were collected in two cobble-bed rivers with mean depths of approximately 0.5 m, relative roughness values between 0.12 and 0.33, and streamflow rates of 1.5 and 3.1 [m.sup.3]/s. The analysis included mean velocity, Reynolds shear stress ([[tau].sub.R]), turbulence intensity (TI), and turbulent kinetic energy (TKE) vertical profiles and horizontal heterogeneity collected in riffle, run, and pool habitat units. The measured profiles were compared with previously reported semiempirical equations. The logarithmic profile reasonably described the vertical velocity profiles. However, the observed TI, TKE, and [[tau].sub.R] profiles deviated noticeably from the semiempirical relationships. Velocity magnitude and cross-correlation coefficients revealed strong spatial heterogeneity at both the reach and fine scales. Spatial heterogeneity was also observed in TI and TKE data, but to a lesser degree. The results provide a novel description of flow field characteristics in cobble-bed rivers while demonstrating techniques for measuring velocity and turbulence distributions in natural streams in the context of an ecohydraulics study. CE Database subject headings: Turbulence; Acoustic techniques; Measurement; Ecology; Open channels; Rivers; Velocity.

An acoustic Doppler velocimeter was used to characterize turbulence in two gravel bed rivers. Data were collected in unobstructed flow and compared to recent investigations. Additional data collected in the wake of emergent boulders indicate that mean flow velocity, turbulent kinetic energy, gradients in the streamwise velocity, and Reynolds stress downstream from large rocks deviate from unobstructed flow results, but similar turbulence patterns are found behind each boulder. Results of this study are discussed with regard to natural channel design and fish habitat. DOI: 10.1061/(ASCE)0733-9429(2005)131:8(635) CE Database subject headings: Turbulent flow: River beds: Fish habitats; Cohesionless sediment: Gravel.

Washington State University, by virtue of the presence of the Albrook Hydraulics Laboratory, maintains several courses devoted to hydraulic engineering. The evolution of hydraulics offerings reflects the needs of the day. Fluid mechanics was emphasized following the World War II dam construction boom, including hydraulic structures and water hammer problems. Present undergraduate offerings are less detailed and more diverse, incorporating introductory level material from several past courses into fewer classes. Offerings are supplemented by other departments. Such a diversification is indicative of civil engineering curricula in general and reflects the smaller number of faculty specializing in hydraulics. Current graduate offerings are evolving to include partnering with neighboring institutions. Such partnering is an effective way to increase the breadth and depth at the graduate level and continue to offer comprehensive graduate education. For example, a total of 17 graduate courses are available from Washington State University and the University of Idaho. The future will likely require further creative partnering, whether on a regional or on a national basis, with video streaming and distance education. European efforts in the field of hydroinformatics merits more attention and discussion.

Flow over a sharp-crested weir can create dangerous countercurrents downstream under high tailwater conditions. A comprehensive experimental design project in open-channel hydraulics used in a senior/graduate course and in a freshman exploratory experience is illustrated. This applied problem allows the instructor to demonstrate hydraulic jumps, aerated versus nonaerated nappes, similitude and modeling, and the need for experimentation in hydraulics. A series of experiments requires students to compare their predictions of several parameters to those measured, and asks them to design a supplemental structure for the weir to reduce the power of the frontal vortex such that people are ejected and carried downstream to calmer water. The student designs are then tested in the flume during class. During the course of the project, spontaneous discussions occur about the extent to which engineers should be held liable for designs that may increase the likelihood of death. The experiments have been well received and have even saved the life of one student who was swept over a dam and caught in the roller downstream.

Hydrosuction sediment-removal systems (HSRS) remove deposited or incoming sediments from reservoirs using the energy represented by the difference between water levels upstream and downstream from a dam. HSRS are briefly described and compared to other reservoir-sediment management options. Hydraulic principles and design procedures are explained and applied to a field test carried out at Lake Atkinson, on the Elkhorn River, in Nebraska. The field study demonstrated that several different inlet shapes are capable of removing deposited sediment at the rate that it enters the reservoir on an annual basis. A ten-step procedure to determine the feasibility of using an HSRS is presented.

Accurate peak discharge estimates are important when sizing highway culverts to prevent possible flood damages and to ensure economic design. The purpose of the undertaken study was to find the most acceptable peak-discharge-estimation method for use on small agricultural watersheds in Nebraska. An analysis of time of concentration [t.sub.c] methods was undertaken because of this parameter's importance in many peak-flow methods. Seven [t.sub.c] equations were compared to recorded [t.sub.c] values from four watersheds each less than 2 sq mi (5.18 [km.sup.2]) in area. Field [t.sub.c] values were derived from a hyetograph-hydrograph analysis. Six peak-flow methods were then compared to the recorded peaks and historical records to find the best estimation method. Based on three storm seasons of data, a modified form of the Kirpich equation and the U.S. Soil Conservation Service average-velocity equation estimate the time of concentration adequately. Peak discharges were most closely predicted using statewide regression equations, the Fletcher method, and the rational method. Results for the 25-year event (culvert design event) tentatively support the use of statewide regression equations.

Recent advancements in desktop-computer multimedia coupled with lower prices have increased the use of this form of educational technology in engineering programs around the country. An example of a self-paced, multimedia module, developed to highlight stream discharge measurements, serves to illustrate what is possible at relatively low prices using midrange desktop computers. The proliferation of such examples, however, raises larger issues that merit discussion in the engineering education community: Who should develop these materials? How should they be incorporated into the classroom? Will faculty find that their efforts jeopardize their promotion and tenure opportunities?

The First Sino-US Workshop on Sediment Transport and Disasters was held in Beijing, China from March 15 to 22, 1999. The workshop, which was attended by 49 Chinese and 12 American engineers and scientists, was conducted to promote sharing of expertise on sediment-related disasters. American participants tackled issues, processes and impacts of sediment-related disasters while their Chinese counterparts discussed problems, tools and solutions.