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Numerical simulation of sedimentation processes in reservoirs as a function of outlet location

International Journal of Sediment Research 2009年第3期24卷 339-351页

作者： horacio toniolo Civil and Environmental Engineering Department University of Alaska Fairbanks

This paper builds on a recently published one-dimensional moving-boundary model of the coevolution of topset, foreset and bottomset in a reservoir that captures the dynamics of the internal muddy pond typical to reservoirs. This model was modified to account for different outlet locations at the reservoir’s downstream end. This model considers a river carrying two sustained phases of sediments: coarse (sand) and fine (mud). The coarse phase deposits in the topset and delta foreset, while the fine phase forms a dilute suspension of wash load in the river. As the river enters the reservoir, the muddy water plunges on the foreset to form a Froude-supercritical (purely depositional) turbidity current. This turbidity current emplaces the bottomset. The modified numerical model was tested against five laboratory experiments previously reported by the author. The model successfully locates the muddy-water/clear-water interface. In addition, modeled and measured bed deposits are in good agreement. Results clearly indicate that the location of the internal hydraulic jump plays a key role in the final bed deposit.

关键词： Numerical model Delta Ponded turbidity currents Outlet location Reservoirs

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DISCUSSION ON “NUMERICAL SIMULATION OF SEDIMENT RELEASE FROM RESERVOIRS” (No. 1,2006) BY KHOSROWNEJAD A. AND NEISHABORI A.

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International Journal of Sediment Research 2007年第1期22卷 80-86页

作者： horacio toniolo Alfredo TRENTO Civil and Environmental Engineering Department University of Alaska Fairbanks Facultad de Ingenieria y Ciencias Hidricas Universidad Nacional del Litoral

Sedimentation processes in reservoirs can be studied by performing theoretical analysis, laboratory experimentation, numerical simulation, or a combination of these three methods. Available literature focused on reservoirs is abundant. For instance, the works conducted by Hotchkiss and Parker (1991), Morris and Fan (1997), and De Cesare et al.

关键词： AND NEISHABORI A BY KHOSROWNEJAD A DISCUSSION ON NUMERICAL SIMULATION OF SEDIMENT RELEASE FROM RESERVOIRS No

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Bed Forms and Sediment Characteristics along the Thalweg on the Tanana River near Nenana, Alaska, USA

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Natural Resources 2013年第1期4卷 20-30页

作者： horacio toniolo Civil and Environmental Engineering Department University of Alaska Fairbanks Fairbanks USA

Sediment sampling and longitudinal river-bottom surveys were conducted along the thalweg on the Tanana River near the city of Nenana, Alaska, USA, to provide basic information for the engineering design requirements of hydrokinetic devices to be deployed in the area. The study reach was located at approximately 64°33'50'N and 149°04'W. The Tanana is a large glacier-fed river, with open-water flow conditions from May to October. The river presents a single channel in the study area. Granulometric analyses of sediment moving near the riverbed reveals the coexistence of three distinctive types of sediment along the study reach: 1) nearly uniform fine sand;2) bimodal distributions containing fine sand and medium gravel;and 3) medium gravel. Preliminary relationships between sediment loads and discharge were developed. Dunes with small superimposed dunes were found along the reach. The basic geometric parameters (i.e., wavelength and height) of dunes were measured, and steepness was calculated. In general, dune wavelength increased with increasing discharge. Dune wavelengths ranged from 41 to 67 m, while small-dune wavelengths ranged from 13 to 16 m. Steepness increased slightly with increasing discharge.

关键词： Sand-Gravel Riverbeds Dunes Steepness Thalweg Suspended-Sediment Load Bed Load

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Hydrokinetic Assessment of the Kvichak River near Igiugig, Alaska, Using a Two-Dimensional Hydrodynamic Model

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Energy and Power Engineering 2012年第6期4卷 422-431页

作者： horacio toniolo Civil and Environmental Engineering Department University of Alaska Fairbanks Fairbanks USA

Two-dimensional hydrodynamic simulations were performed on a monthly basis along 2.5 km of the Kvichak River near Igiugig in southwest Alaska, USA, to estimate flow conditions and to assess the hydrokinetic potential of the river reach. Instantaneous power density function along the computational domain was calculated. Study results indicate that two areas may be suitable for deploying turbines. The best option is located near the town, where the channel is relatively straight. A second possible site is located near the end of the study reach (approximately 2.3 km, along the river, from Lake Illiamna). Monthly-averaged velocities along the thalweg ranged from 1.7 to 2.7 m/s;and from 1.1 to 2 m/s at the upstream and downstream sites, respectively. Similarly, averaged values for the instantaneous power density, reduced by an extraction coefficient, were approximately 1500 and 5500 W/m2 during April and September, respectively, at the upstream site, as well as 400 and 2500 W/m2 for the same months at the downstream site. It was found that a previous resource assessment, which considered cross-sectionally averaged velocities, substantially underestimated the available power density along the river reach. Finally, the importance of having adequate bathymetric data is demonstrated by comparing field measurements with model simulations.

关键词： Stream Resource Assessment Numerical Modeling Power Density

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Hydraulic Characteristics and Suspended Sediment Loads during Spring Breakup in Several Streams Located on the National Petroleum Reserve in Alaska, USA

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Natural Resources 2013年第2期4卷 220-228页

作者： horacio toniolo Dragos Vas Peter Prokein Richard Kenmitz Erica Lamb Dave Brailey Brailey Hydrologic Consultants Anchorage USA Bureau of Land Management Arctic Field Office Fairbanks USA Civil and Environmental Engineering Department University of Alaska Fairbanks Fairbanks USA Institute of Northern Engineering University of Alaska Fairbanks Fairbanks USA Water and Environmental Research Center University of Alaska Fairbanks Fairbanks USA

This article presents results from a broad field campaign involving discharge and surface-water slope measurements, water sampling, and longitudinal river-bed profile surveys. During the spring breakup of 2011, fieldwork was carried out in several pristine streams located in the National Petroleum Reserve in Alaska;the studied streams cover two main regions: 1) foothills (Ikpikpuk River, Seabee Creek, Prince Creek, and Otuk Creek);2) coastal plain (Fish Creek, Judy Creek, and Ublutuoch River). Reported data includes basic geometric and hydraulic characteristics such as channel width and depth, cross-sectional area, average velocity, friction factor, shear stress, suspended sediment concentrations from autosamplers and grab samples, and dune dimensions and steepness ratios. The measured discharge in different streams ranged from 2 to 853 m3/s, which corresponded to post-breakup and near peak conditions, respectively. The temporal variation of Manning’s n was in phase with measured discharge, with high values of n associated with the presence of floating ice during the measurements. Calculations indicate that sediment particle sizes ≤2 mmmoved during the measurements. In general, variations in discharge were accompanied by changes in suspended sediment concentrations.

关键词： Suspended Sediment Concentration Bedforms Resistance Coefficient Spring Breakup Arctic Hydrology

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