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Open channels are one of the most used water conveyance systems for delivering water for different purposes. Existing models for the design of open channels mainly assume uniform flow, focus on cross-section sizing, and generally decouple cross-section sizing from the selection of channel alignment and profile. In this study, we developed an optimization model for a comprehensive design of transmission channels. The model minimizes the sum of costs for earthwork, lining, water losses, and land acquisition; accounts for non-uniform, mixed-regime flow; and considers multiple geometric and hydraulic constraints. The model was validated using several idealized scenarios. The model potential in minimizing the cost of real open channel projects was demonstrated through application to an existing irrigation water transmission canal in Egypt (the Sheikh Zayed Canal). The results of validation scenarios matched the anticipated outcomes for channel profile and alignment and reproduced analytical solutions given in the literature for channel cross-section design. Application of the model to the Sheikh Zayed Canal gave a more optimal design; the OCCD model produced a design alternative with ~27% less cost than the constructed alternative.

A comprehensive optimization model was developed to identify the optimal set of non-storage based small hydropower projects (SHP) along a given river reach. The model was based on a greedy genetic algorithm that maximizes net annual benefit. For each project, the model determines intake location, penstock diameter and length, and turbine number and capacity. The novel features in the model include: 1) bi-level optimization that produces robust results, 2) improved search for SHP intake locations, 3) inclusion of turbine number as an explicit optimization variable, and 4) nested optimization modules and parallelized execution. Model performance was assessed through application to the Mamquam River in Canada and the Guder River in Ethiopia. For the Mamquam River, the model identified seven feasible projects. The model provided suggestions for further improvement of one of the two existing SHPs on the river through shifting the intake 1.2 km upstream of the existing intake to provide a greater net benefit. No SHPs have been constructed on the Guder River yet; however, the model suggested 19 potential SHPs that could provide 62% higher annual net benefit compared to the results of a previous model recently applied to the same study area.

A three-dimensional numerical model was applied to simulate submerged spatial hydraulic jumps (SSHJ) downstream of a symmetric vent that discharges into a wider channel. Simulations were carried out for different aspect ratios of the vent, expansion ratios of vent width to downstream channel width, tailwater depth, and inlet Froude number. Depending on these factors, simulations indicated the formation of steady asymmetric SSHJ, oscillatory asymmetric SSHJ, and steady symmetric SSHJ, consistent with results of previous experimental studies. The model reproduced observed depth downstream of vent, jump length, and velocity profiles along channel centerline for steady symmetric SSHJ. For oscillatory asymmetric SSHJ, simulated oscillation frequencies had Strouhal numbers that varied with expansion ratio and ranged between 0.003 and 0.015. With piers downstream of the vent, oscillatory SSHJ continued to exhibit jet deflections when pier length was relatively short ( ≲ 0.2 of jump length) but became steady asymmetric for longer piers.

An optimal planning and preliminary-design (OPD) model was developed to maximize the annual net benefit of run-of-river (RoR) hydropower projects along a stream. The OPD model identifies optimal, non-overlapping RoR projects along the given stream. For each project, the OPD model determines intake location; penstock diameter and length; and type, number, and discharge of turbines. The OPD model applies genetic algorithm in two stages. The first stage optimizes design of individual potentially overlapping projects densely spaced at uniform intervals along the stream and the second stage determines the set of non-overlapping projects that maximizes the net hydropower benefit. Results of the OPD model compared favorably to results of previous models for a hypothetical case study. Further application of the OPD model to idealized case studies with different stream elevation profiles and with tributary flows indicated that the model gives reliable results. The OPD model was used to identify optimal RoR projects for the Guder River, Ethiopia. The OPD model identified 22 optimal RoR projects covering ∼49 km of the 127-km-long Guder River. The total annual generated energy from the identified projects is ∼540 GWh and the installed capacity for individual projects ranges between ∼1 MW and 21 MW.

Pressure reducing valves (PRVs) are typically used to regulate excessive pressure in water distribution networks. During transient events, the dynamic response of PRVs may adversely affect pressure fluctuations in distribution networks. In this study, the dynamic response of PRVs was analyzed by developing a numerical model that coupled an existing water-hammer model and a two-parameter dynamic PRV model. PRV parameters were calibrated, and the model was validated using previous experimental observations. The model was then used to study the effect of PRV dynamics during transient events in a distribution network. To optimize the rate of PRV opening and closure and control its dynamic response, the model was interfaced with an optimization algorithm based on shuffled complex evolution. The applied objective function gave PRV parameters that accelerated damping of the transient pressure waves and minimized the root-mean-square deviation from post-transient steady pressure at all nodes in the network. The results of this study indicate the importance of accounting for PRV response when simulating transients in water distribution networks. This study also highlights the need for PRV manufacturers to include in their product catalogs dynamic PRV parameters for use in transient analysis.

Field data and a forced, modal-based, two-layer, variable-cross-section model (TLVC) were used to examine the baroclinic response to wind in a large multibasin reservoir, Nechako Reservoir (British Columbia, Canada). The TLVC showed that most of the thermocline deflections at the dam could be accounted for by considering the first two basins upstream of the dam, Knewstubb and Natalkuz Lakes, and that the thermocline deflections were dominated by the first (H1) and second (H2) horizontal baroclinic modes of the combined basins. Calibration of the TLVC against the field data showed that the H1 and H2 modes were strongly damped, with effectively no free thermocline oscillations. This strong damping had two effects: high coherence between the wind and thermocline deflections and phase lags between thermocline deflections at different locations. The damping in Nechako Reservoir is stronger than in many lakes, and results from both high velocities within the geometric constriction between Knewstubb and Natalkuz Lakes and drag due to submerged trees, which cover 30% of the bed. Our study provides a picture of overdamped baroclinic response and shows how useful information about the baroclinic response in complex bathymetries can be obtained using relatively simple tools such as the TLVC.

We examined the effect of along-thalweg depth variability on the baroclinic response to wind in elongated narrow basins with a sharp thermocline. The effect of depth variability was examined by deriving a modal-based forced model with two density layers and applying the model to a symmetric curved-bottom basin (CB), an asymmetric wedge-shaped basin (with a sloping bottom towards a vertical wall, WB), and a flat-bottom basin (FB). The baroclinic responses of CB, WB, and FB to uniform wind were found to differ in time-scale, number and energy of excited modes, and temporal pattern and along-thalweg structure of baroclinic flow and thermocline deflection. For all bottom profiles that were examined, the fundamental mode was found to dominate the response to spatially-uniform wind. Compared to FB, the asymmetric depth variability in WB increased the number and energy of excited higher modes and localized the interface shear, while the symmetric deviation from flat bottom in CB caused the opposite effects. Linear deviation from uniform wind was found to feed energy into higher baroclinic modes for the symmetric CB, but was found to reduce the energy of higher baroclinic modes for WB when the deviation from uniform wind is comparable to the spatial-average magnitude. Our results can explain the observation of the second baroclinic mode and irregular wave patterns in some lakes and reservoirs. Further, our results suggest that one-dimensional vertical mixed-layer models provide better results for shear entrainment in curved-bottom basins than in wedge-shaped basins.

Field data and two linear layered models were used to examine the baroclinic response to wind in a small elongated two-basin lake, Amisk Lake (Alberta, Canada). For the first vertical baroclinic mode, wind-forced horizontal modes were simulated using a dynamic two-layer variable cross-section (TVC) model. The first horizontal mode, H1, was found to dominate the exchange between the two basins of Amisk Lake. The highest velocities associated with H1 occurred in the constricted channel connecting the two basins. This high velocity led to strong damping which brought H1 in near-resonance with the diurnal wind despite a difference in periods. Along with H1, the second horizontal mode, H2, was detected at a thermistor mooring. The TVC showed that H2 resulted from the coupling between along-thalweg wind distribution and the bathymetry of Amisk Lake. The damping for H2 was found to be weaker than for H1, likely because of weaker bottom drag in the connecting channel. The evolution of vertical H1 modes were simulated using a multi-layered box model. In response to wind pulses, the first vertical mode V1H1 initially dominated over higher vertical modes causing two-layer exchange. Following the faster decay of V1H1, higher vertical modes shifted the exchange to three and more layers. Our study shows the importance of the coupling between wind stress distribution and lake bathymetry in exciting horizontal modes, reveals the effect of damping on resonance with wind, and explains the evolution of exchange associated with vertical modes.

As humans venture back to the Moon, or onward to near-Earth objects and Mars, it is expected that the rigors of this exploration will far exceed those of Apollo. Terrestrial analogs can play a key role in our preparations for these complex voyages, since in addition to their scientifi c value, analogs afford the exploration community a means to safely prepare and test exploration strategies for future robotic and human planetary missions. Many relevant analog studies exist, and each is focused on a particular aspect of strategic development. Some analog programs such as the Pavilion Lake Research Project (PLRP) present the opportunity to investigate both real scientifi c and real exploration scenarios in tandem. The activities of this research program demand the use of techniques, tools, and strategies for underwater scientifi c exploration, and the challenges associated with the scientifi c exploration of Pavilion Lake are analogous to those human explorers will encounter on other planetary and small solar system bodies. The goal of this paper is to provide a historical synopsis of the PLRP’s objectives, milestones, and contributions to both the scientifi c and exploration community. Here, we focus on detailing the development and deployment of an integrated science and exploration program with analog application to our understanding of early Earth systems and the preparation for future human space exploration. Over a decade of exploration and discovery is chronicled herein. Spec483_CH07_p085-116.indd 86 29/09/11 7:13 PM A historical overview of the Pavilion Lake Research Project 87 spe 483-01 page 87 THE SCIENTIFIC DISCOVERY OF PAVILION LAKE