One of the most cost-effective and environmentally sound methods of developing hydropower is through the uprating of hydroelectric turbines. In many countries hydroelectric dams have turbines that ...are approaching their expected service life, with plans underway to install replacement turbines that are expected to improve fish passage survival. To validate these improvements, there is a need to develop a baseline hydraulic characterization of existing Kaplan turbines. An autonomous sensor device known as the Sensor Fish was deployed at Ice Harbor Dam to characterize the hydraulics under different operating conditions. Nadir pressures varied by operating condition, with values decreasing with operating power (144–106 kPaA). Pressure changes during turbine passage varied by operating condition, with values increasing with operating power (311–344 kPa). There were slightly more significant events (acceleration ≥95G) in the stay vane/wicket gate region than the runner region. Rotational velocity data were similar between operating conditions. Sensor Fish data amassed during field studies in similar turbines were used for comparison. This study offers critical insights into the biological performance of large Kaplan turbines and provides vital information that can be used to make informed decisions that lead to additional design or operational improvements.
•Sensor Fish data collected in a large Kaplan turbine at Ice Harbor Dam.•Nadir pressure and rotational velocity were lowest among turbines compared.•Severe acceleration events were similar among the turbines compared.•Data provides insight into the biological performance of large Kaplan turbines.•Data provides information that can lead to further design/operational improvements.
Siphon turbines are an attractive type of small-scale hydropower turbines because they can be retrofitted into existing structures where there is already a drop in water elevation. A siphon turbine ...conveys water from an upper reservoir to a lower reservoir through the use of a siphon structure that goes over the top of the dam. A small, neutrally buoyant autonomous sensor package known as a Sensor Fish was deployed through a siphon turbine at the Head of the U Hydroelectric Project in Idaho, USA. Comparisons were made between the siphon turbine in this study and other low-head turbines that have been studied using Sensor Fish. The Sensor Fish measurements indicate that this siphon turbine can generate nadir (i.e., minimum) pressures during runner passage of 22.4 kPaA, which is much lower than those of other low-head turbine types that have been studied using Sensor Fish and could be potentially harmful to fish species susceptible to barotrauma injury. Severe acceleration events occurred in the wicket gate and runner regions at rates of 12% and 47% respectively. These numbers are comparable or lower than other low-head turbines that have been studied with Sensor Fish. Due to the low nadir pressures measured, stakeholders should determine the presence of any fish species-of-concern in the area that are susceptible to barotrauma, and if so, methods to avoid or reduce fish entrainment such as screening technologies or diversions should be investigated.
•Sensor Fish used to characterize hydraulic conditions through a siphon turbine.•Nadir pressures measured during runner passage were very low (22.4 KPaA).•Over 50% of releases experienced at least one occurrence of high acceleration.•Data can be used to guide cleaner power production from low-head hydropower.
Hydrologic exchange flux (HEF) is an important hydrologic component in river corridors that includes both bidirectional (hyporheic) and unidirectional (gaining/losing) surface water‐groundwater ...exchanges. Quantifying HEF rates in a large regulated river is difficult due to the large spatial domains, complexity of geomorphologic features and subsurface properties, and the great stage variations created by dam operations at multiple time scales. In this study, we developed a method that combined numerical modeling and field measurements for estimating HEF rates across the riverbed in a 7 km long reach of the highly regulated Columbia River. A high‐resolution computational fluid dynamics (CFD) modeling framework was developed and validated by field measurements and other modeling results to characterize the HEF dynamics across the riverbed. We found that about 85% of the time from 2008 to 2014 the river was losing water with an annual average net HEF rates across the riverbed (Qz) of −2.3 m3 s−1 (negative indicating downwelling). June was the only month that the river gained water, with monthly averaged Qz of 0.8 m3 s−1. We also found that the daily dam operations increased the hourly gross gaining and losing rate over an average year of 8% and 2%, respectively. By investigating the HEF feedbacks at various time scales, we suggest that the dam operations could reduce the HEF at seasonal time scale by decreasing the seasonal flow variations, while also enhance the HEF at subdaily time scale by generating high‐frequency discharge variations. These changes could generate significant impacts on biogeochemical processes in the hyporheic zone.
Plain Language Summary
Dam operations regulate downstream water flow and modify the surface water and groundwater interactions. In this study, we simulated river and groundwater dynamics in a 7 km long reach of Columbia River using a high‐resolution numerical model. Due to the upstream dam regulations, the daily river stage variation of our study reach could be as high as 2 m. We found that about 85% of the time from 2008 to 2014 the river was losing water with an annual average net HEF rates across the riverbed of 2.3 m3 s−1. June was the only month that the river gained water, with gaining rate of 0.8 m3 s−1. We also found that the daily dam operations enhanced the losing and gaining activities, which may lead to great impact on riverbed biogeochemical processes.
Key Points
A coupled CFD model was used to simulate hydrologic dynamics in a large regulated river reach (about 7 km long, 800 m wide)
Daily dam operations increased the river gaining and losing rates by 8% and 2%, respectively
This approach can be extended to basin scale by combining with geomorphological and hydrogeological characterizations
Evaluating fish behavior and migration in response to environmental changes is a fundamental component of fisheries research and recovery of freshwater ecosystems. While spatial distribution and ...behavior of fishes has been well studied around hydropower facilities, little research has been conducted at a mid-reach location between two dams. The Juvenile Salmon Acoustic Telemetry System (JSATS) cabled receiver system was developed and employed as a reference sensor network for detecting and tracking juvenile salmon in the Columbia River Basin. To supplement acquisition of detection and three-dimensional (3-D) tracking data to estimate survival and fish behavior in the forebays of Little Goose and Lower Monumental dams on the Snake River in eastern Washington State, a mid-reach location was needed to investigate the spatial distribution of migrating juvenile salmon in open-water conditions between the two dams. Lyons Ferry Bridge on State Route 261 at the confluence of the Snake and Palouse Rivers was chosen as the mid-reach location. A JSATS-cabled receiver system configuration was successfully designed and deployed from the bridge's pier structure. Theoretical analysis confirmed the functionality and precision of the deployment design. Validation tests demonstrated sub-meter accuracy of 3-D tracking up to a horizontal distance of 50m upstream and downstream from the Lyons Ferry Bridge piers. Detection and tracking probabilities of the LFB cabled array were estimated to be 99.98% from field application. This research provided a detailed description of acoustic telemetry system deployment and 3-D tracking as guidance for better understanding of fish migration behavior as they pass through dams and continue downstream through the river between dams.
Acoustic telemetry receivers are used across a range of aquatic habitats to study a diversity of aquatic species. The Juvenile Salmon Acoustic Telemetry System autonomous acoustic receiver system was ...deployed and moored in the Columbia River and its estuary. A high receiver loss rate during 2005 in the Columbia River estuary, an area with high water velocities and unstable substrates, prompted improvements to the receiver mooring system, and in 2006 the mooring system was redesigned. This change included elimination of surface buoys, a cable bridle, and an anchor tagline (for anchor recovery). The new mooring configuration, consisting of an acoustic receiver, acoustic release, and mooring line sections that were anchored to the riverbed, improved receiver recovery rates and crew safety. Additionally, a reward program was implemented to provide an incentive for people to return found receivers. The mooring design presented here performed well compared with previous acoustic receiver mooring methods used in the Columbia River system and should be useful for similar applications in large rivers and estuaries with high water velocities and shifting substrates.
Semiarid ecosystems play a critical role in determining the interannual variability of the global terrestrial carbon sink. Water availability is a critical driver of productivity in semiarid ...ecosystems, which often alternate between carbon sink/source functioning during wet/dry years. In this study, we investigate how groundwater availability resulting from groundwater‐river water exchange influences net ecosystem exchange of CO2 (NEE), evapotranspiration (ET), and the surface energy balance at two semiarid ecosystems along the Columbia River in central Washington, USA. We examined 1 year of eddy covariance measurements from an upland sagebrush ecosystem primarily fed by rainfall without groundwater access and a riparian grassland ecosystem with groundwater access during the dry season due to lateral groundwater‐river water exchange. The two sites had distinct seasonal patterns of NEE and ET, driven by differences in water availability. While NEE at the upland sagebrush site was strongly constrained by water availability during the dry months, access to groundwater allowed the riparian site to maintain high NEE magnitude and ET during the same dry months. The riparian site had larger annual gross primary productivity than the upland site (612 vs. 424 gC/m2), which was offset by higher ecosystem respiration (558 vs. 363 gC/m2). Thus, the magnitude of the annual NEE at the upland site was larger than that at the riparian site (−62 vs. −54 gC/m2). Our results demonstrate that groundwater access determined by connectivity between groundwater and surface water can be a critical driver of carbon uptake and ET in semiarid ecosystems.
Plain Language Summary
Semiarid ecosystems play a critical role in determining the interannual variability of the global terrestrial carbon sink. Water availability is a critical factor influencing the productivity of semiarid ecosystems, which often alternate between functioning as carbon sinks during wet years and carbon sources during dry years. In this study, we investigate how groundwater availability resulting from groundwater‐river water exchange influences carbon uptake and evapotranspiration at two semiarid ecosystems along the Columbia River corridor in central Washington, USA. We examined 1 year of measurements from an upland sagebrush ecosystem without groundwater access and a riparian grassland ecosystem with access to groundwater during the dry season due to lateral groundwater‐river water exchange. The two sites had distinct seasonal patterns of carbon uptake, driven by differences in water availability between the two sites. While carbon uptake at the upland sagebrush site was strongly constrained by water availability during the dry summer months, access to groundwater allowed the riparian site to maintain high carbon uptake and evapotranspiration during the same dry months. Our results demonstrate that groundwater access can be a critical factor influencing carbon uptake and evapotranspiration in semiarid ecosystems.
Key Points
The effects of water accessibility on carbon and water cycling in semiarid ecosystems are investigated
Carbon uptake was strongly constrained by moisture availability during dry months in an upland ecosystem without groundwater access
Lateral groundwater‐river water exchange allowed a riparian semiarid ecosystem to maintain high carbon uptake and evapotranspiration during dry months
Semiarid ecosystems play a critical role in determining the interannual variability of the global terrestrial carbon sink. Water availability is a critical driver of productivity in semiarid ...ecosystems, which often alternate between carbon sink/source functioning during wet/dry years. In this study, we investigate how groundwater availability resulting from groundwater-river water exchange influences net ecosystem exchange of CO2 (NEE), evapotranspiration (ET), and the surface energy balance at two semiarid ecosystems along the Columbia River in central Washington, USA. We examined 1 year of eddy covariance measurements from an upland sagebrush ecosystem primarily fed by rainfall without groundwater access and a riparian grassland ecosystem with groundwater access during the dry season due to lateral groundwater-river water exchange. The two sites had distinct seasonal patterns of NEE and ET, driven by differences in water availability. While NEE at the upland sagebrush site was strongly constrained by water availability during the dry months, access to groundwater allowed the riparian site to maintain high NEE magnitude and ET during the same dry months. The riparian site had larger annual gross primary productivity than the upland site (612 vs. 424 gC/m2), which was offset by higher ecosystem respiration (558 vs. 363 gC/m2). Thus, the magnitude of the annual NEE at the upland site was larger than that at the riparian site (-62 vs. -54 gC/m2). Furthermore, our results demonstrate that groundwater access determined by connectivity between groundwater and surface water can be a critical driver of carbon uptake and ET in semiarid ecosystems.
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