Fluctuation of hyporheic zone thickness due to inflow and outflow across the water-sediment interface
Determination of hyporheic zone thickness in streams is an important step for study of stream-aquifer interactions. Knowledge about hyporheic zone thickness is useful in stream restoration. However, because there is a lack of standard techniques for such study, evaluation of the hyporheic zone thickness for a given stream reach remains a challenge task for researchers. This paper presents Galerkin finite element flow and stream function models that can simulate the hyporheic zone thickness. The flow and stream function equations are solved for 2-D profile domains that can be across a stream or parallel to a stream. The numeral schemes for solving the flow and stream function equations and the treatment of boundary conditions are described. Hypothetical streams are used for simulation of the control of hyporheic zone thickness by the magnitude of inflow and outflow that occur at the stream-sediment interface. Groundwater flow velocity field is generated to examine the flow dynamics in hyporheic zones. The magnitude of groundwater flow velocity in hyporheic zone is greater than that of regional groundwater flow.
Hyporheic Zone in Urban Streams: A Review and Opportunities for Enhancing Water Quality and Improving Aquatic Habitat by Active Management
Abstract Tremendous opportunities exist for enhancing water quality and improving aquatic habitat by actively managing urban water infrastructure to operate in conjunction with natural systems. The hyporheic zone (HZ) of streams, which is the area of active mixing between surface water and groundwater, is one such system that is overlooked by many water professionals, because the state of the science on this topic has not been transferred into practice. As a biogeochemically active zone, the HZ offers great potential to provide natural treatment of organic compounds, nutrients, and pathogens in urban streams, which are often strongly impacted by flow modifications and water pollution. Reliable treatment is most likely in streams in which the majority of flow occurs through the HZ, the flow is aerated, and sufficient residence times occur, which may be limited to specific channel morphologies and seasons. Integration of the HZ into stream management plans could also provide quality habitat in a landscape w...
Synthesis of β-FeSi2 nanowires by using silicon nanowire templates
Si nanowires templates were grown by a Cu-catalyzed vapor–liquid–solid process and used for the preparation of β-FeSi2 nanowires on a Si substrate. The silicon nanowires were transformed into β-FeSi2 nanowires by annealing with additional source material containing FeCl2 and Si powder. In contrast to uniform Si nanowire templates along the direction, the synthesized nanowires were deformed irregularly. The electron diffraction pattern of the nanowires synthesized from the template corresponded to that of single-crystalline β-FeSi2 and the longitudinal direction of the nanowire was along the direction. The energy dispersive X-ray fluorescence analysis confirmed that the nanowire contained Fe and Si in an atomic ratio of approximately 1:2. The results confirmed that β-FeSi2 nanowires on a Si substrate were synthesized from the Si nanowire templates.Si nanowires templates were grown by a Cu-catalyzed vapor–liquid–solid process and used for the preparation of β-FeSi2 nanowires on a Si substrate. The silicon nanowires were transformed into β-FeSi2 nanowires by annealing with additional source material containing FeCl2 and Si powder. In contrast to uniform Si nanowire templates along the direction, the synthesized nanowires were deformed irregularly. The electron diffraction pattern of the nanowires synthesized from the template corresponded to that of single-crystalline β-FeSi2 and the longitudinal direction of the nanowire was along the direction. The energy dispersive X-ray fluorescence analysis confirmed that the nanowire contained Fe and Si in an atomic ratio of approximately 1:2. The results confirmed that β-FeSi2 nanowires on a Si substrate were synthesized from the Si nanowire templates.