Delta progradation, reservoir infill, and deposit removal in idealized and field reservoirs
Date Issued
2016
Date
2016
Author(s)
Ke, Wun-Tao
Abstract
The aim of this thesis is to present the curved delta progradation, longitudinal reservoir infill, and hydrosuction removal deposits in idealized reservoir. The mathematical theory, numerical computation, laboratory experiments, and field observations are used to illustrate the delta progradation. Based on the Exner equation expoliting the special properties of solutions to the eikonal euation with the finite angle of repose, we derive a formula for delta front progradation rate applicable to arbitrary shoreline shape. Applying this delta front progradation rate formula, numerical computation results for two-dimensional delta are illustrated as the applications. In a case of the radially symmetrical delta prograding over a horizontal plane, an analytical solution is obtained and comfirms the numerical computation results. An exploring numerical case is to model the delta supplied by a point sediment source prograding over an inclined rigid basement into a basin with a constant standing water level. To compare with the numerical computation results, a small-scale laboratory experiment was conducted. The delta fed by a point sediment source upstrem develops over an inclined rigid basement entering a body of standing water with a constant level. The delta deposits are surveyed during experiments by video imaging of a scanned laser sheet. Through the imaging measurements of the entire delta deposits, a series of formation evolution and DTM are acquired. The characteristics of experimental delta including the perimeter and area of marsh and topset are used to compare to the field landscape of Mossy delta where is in the Mossy River, Saskatchewan, Canada. The DTM results are analyzed to obtain the sediment flux through the shoreline and distribution over foreset. Wushe Reservoir is selected for the field case study site of delta progradation. We surveyed the long-profile including the topset upstream and reservoir bathymetry for four times and collect the sedimentation measurements over past decades. We then derive a simplified theory from the Exner equation to obtain three analytical self-similar solutions for the longitudinal reservoir infill. The numerical computation of finite volume method is applied to compare with analytical self-similar solutions. The simplified numerical computation is used to simulate the field reservoir. To remove the sediment deposits in the reservoir and extend the life of the reservior, the hydrosuction sediment removal which is used to draw water and sediment into pipeline and convey the slurry out of reservoir is an option without empty the entire reservoir. The sediment concentration of the slurry depneds largely on the degree of the sediment consolidation of the bottom deposits. To investigate the influence by degree of sediment consolidation, a series of laboratory experiments were conducted using a small-scale suction pipe equiped with an online densimeter to measure the time evolution of the outflow sediment concentration. An inviscid selective withdrawal theory is applied to compare to the experiment results. Finally, the exploring experiment for hydroscution sediment removal on geotechnical centrifuge provides possiblies for future researches.
Subjects
艾克納方程式
三角洲演進過程
自相似方程式解析解
水力抽砂
泥砂壓密
Type
thesis
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