| Due to the limited and slow effectiveness of traditional hydraulic sediment removal measures,the effect of reducing sedimentation in reservoirs is not ideal.Simultaneously,as national urbanization progresses and engineering technology rapidly develops,individuals have raised demands for reservoir sedimentation control projects that are more long-lasting and effective.Therefore,manual dredging has become a more effective measure for reducing reservoir sedimentation.However,currently,most dredging projects both domestically and internationally rely on past engineering experience to design dredging locations and forms,lacking theoretical basis.Therefore,this article takes the Wangyao Reservoir,a reservoir with many sandy rivers in the northwest region of China,as an example,and proposes a method of manually shaping the "reservoir capacity"(referred to as the reservoir dredging body in this article).It focuses on the problem of how to determine the dredging location and form of the reservoir when it must be cleared,and conducts research and analysis on the ultimate reservoir capacity theory.Using this as the basis,the design of the reservoir dredging structure was carried out,and a one-dimensional mathematical model that does not couple water and sediment was employed to replicate the erosion and sedimentation process in the reservoir region under various design proposals of the dredging structure.The findings of this study offer technical assistance for the Wangyao Reservoir dredging and expansion plan,as well as provide a methodology for other real-world projects that aim to address reservoir dredging issues.The paper can be summarized as follows in terms of its main content and conclusions:(1)Based on the equilibrium trend law of reservoir erosion and sedimentation development,the research results of the ultimate storage capacity theory of reservoirs,including the reasons for the formation of the ultimate storage capacity,the formation process,morphological parameters,and the calculation formula of the ultimate storage capacity,have been summarized.(2)A mathematical model,which is one-dimensional and does not couple water and sediment,has been developed for simulating sediment erosion and deposition in the Wangyao Reservoir.Furthermore,the model’s control equations,discretization methods,and correlation coefficients were described in detail,separately for the hydraulic calculation module and sediment calculation module,followed by the calibration process.Simultaneously,utilizing the flow rate and sediment transport data from 2015 to 2020,along with the measured storage capacity curves and terrain data of Wangyao Reservoir during the same period,a simulation of the erosion and sedimentation of water and sediment in the reservoir was carried out for a duration of 6 years,and the model parameters were calibrated accordingly.The reliability of the onedimensional water and sediment erosion and sedimentation non coupling mathematical model of Wangyao Reservoir was verified.The validation findings demonstrate that the model can essentially depict the alterations in riverbed erosion and sedimentation within the reservoir area,and can be utilized for examining the erosion and sedimentation process of Wangyao Reservoir under various initial boundary conditions.Furthermore,the model produced sedimentation thickness and cumulative sedimentation amounts that are in good agreement with the measured results during the 6-year erosion and sedimentation evolution process of Wangyao Reservoir.(3)The optimal longitudinal and transverse morphological parameters for the dredging body of Wangyao Reservoir were determined,and the rationality of the optimal longitudinal and transverse morphological parameters was demonstrated.Based on the numerical simulation results,the optimal longitudinal shape parameters of the reservoir’s dredging body are obtained:the longitudinal gradient of the dredging body in the main stream Xingzi River is 4.14 ‰,the elevation difference of the dredging body in front of the dam is 20.23 meters,the longitudinal gradient of the dredging body in the tributary Chalugou is 4.18 ‰,and the elevation difference of the dredging body in front of the dam is 19.76 meters;The optimal lateral shape parameters of the reservoir dredging body:the slope coefficient of the trapezoidal part of the main stream Xingzi River dredging body is 7,the width of the rectangular part is 24.81m,and the depth of the rectangular part is 1.02m.The slope coefficient of the trapezoidal part of the tributary Chalugou dredging body is 6,the width of the rectangular part is 9.80m,and the depth of the rectangular part is 0.62m.At the same time,it is concluded that under the condition of ensuring the same volume and horizontal shape of the reservoir’s dredging body,the longitudinal gradient of the dredging body is larger,but the dredging effect is better when it does not exceed the ultimate storage capacity of the reservoir;Among all the lateral parameters of the reservoir dredging body,adjusting the river width B of the rectangular part of the dredging body and the slope coefficient m of the trapezoidal part of the dredging body to not exceed the ultimate storage capacity of the reservoir has a greater impact on the reservoir dredging effect.Finally,a rationality analysis was conducted on the optimal longitudinal and transverse shape design parameters,and the results showed that the idea of determining the optimal longitudinal shape design parameters first and then obtaining the optimal transverse shape parameters based on this is feasible and reasonable.(4)Using the net benefit value method and numerical simulation results,the issue of whether the artificial shaping of the ultimate storage capacity scheme is better than the artificial shaping of the reservoir dredging body scheme was demonstrated.The calculation results indicate that the net dredging benefit of manually shaping the reservoir dredging body is 326.9 million yuan,which is economically feasible;The net benefit of manually shaping the ultimate storage capacity for dredging is-3974 million yuan,which is not economically feasible.The artificial shaping of reservoir dredging scheme is superior to the artificial shaping of ultimate storage capacity scheme. |
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