Rapid acceleration of cloud-top outflow near vigorous storm updrafts can be readily observed in Geostationary Operational Environmental Satellite-14 (GOES-14) super rapid scan (SRS; 60 s) m...

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Relationships between Deep Convection Updraft Characteristics and Satellite-Based Super Rapid Scan Mesoscale Atmospheric Motion Vector–Derived Flow

Sediment deposition is a significant feature of a dynamic floodplain river. As the river's carrying capacity decreases, it is forced to deposit sediment on the river bed. However, due to the construction of some hydraulic structures over the river bed at different times (bridges, dams), the velocity of the river in the floodplain area decreases with accelerating sedimentation process, which hinders water transport. The sub-catchment basin (Nabadwip-Kalyani stretch) of the Bhagirathi–Hooghly river in West Bengal (Ghosh et al. 2020), India is frequently used as a means of water transport by local stakeholders. Because of sedimentation, the thalweg depth of the river is constantly decreasing in Nabadwip–Kalyani stretch and the water transport is being disrupted. Therefore, it is very important to know the function of hydraulic structures over the river bathymetry and resultant sediment flow, transportation, and sediment deposition in this region. Therefore, this article mainly assesses to develop a 1D hydro-dynamic sediment transport model on river morphological change through seasonal quasi-unsteady flow accumulation and sediment budget in a given year (2018). The hydro-dynamic model is calibrated by 1D HEC-RAS v 5.0.7 software (Gibson et al. 2017) based on seasonal quasi-unsteady flow using various empirical equations and Manning's roughness coefficient and validated with R2, NSE, and RSR. The model also examines the role of hydrodynamic structures in scouring and sedimentation due to the location of these structures above the river. This model output will help local stakeholders to understand the amount of sediment in the river and keep river transport viable in all seasons.

Assessing the nature of sediment transport with bridge scour by 1D sediment transport model in the sub-catchment basin of Bhagirathi–Hooghly river

The present study was carried out to determine the possible origins of sediments entering Taleghan Dam in northern part of Iran, in order to avoid further sedimentation and helping in extension of the useful life of the proposed dam. This was performed by XRD analysis. To do so, first of all, sediment sampling points were positioned along the Taleghan River. The collected samples, after coding, were transferred to the laboratory for mineralogical testing. Then, the samples were exposed to X-ray diffraction analysis. The experimental results were compared with data from geology, land cover land use and slope maps in order to find the possible primary origins of deposits in the Taleghan Dam. Furthermore, the geological formations and physiographical parameter such as slope were also analyzed to test erodibility of the formations. The results showed that most sediment samples in Taleghan are of sedimentary sandstone, mainly containing the quartz and plagioclase minerals (quartz sandstone and arkose sandstone). The findings also showed that calcite and dolomite were abundant in the collected samples, while aragonite and anthracite were found to a lesser extent in the samples. Accordingly, acidic and alkaline formations, mudstone, and siltstone of Karaj area formations, the gypsum of upper red formation, particularly at places with steep slope with a dominance of rangeland land use type, are main origins of sediments in the Taleghan reservoir. In another hand, the control of sediments at these areas would substantially decrease total sediment yields of the entire basin as in the dam reservoir.

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Source apportionment of the sediments entering dam using lithological and mineralogical studies

The mathematical model of Area-Reduction empirical method is written through MATLAB software. Three periods of the hydrologic survey are required to run, calibrate and validate the model. The Dez Dam, which is one of the most significant dams of the Middle East with three periods of hydrographic surveys in 1972, 2002 and 2011, has been chosen for the investigation. The annual average of the input sediment load to this reservoir was calculated by summation of the suspended load and bed load that were estimated through the sediment rating curve and experimental Karaushev curve, respectively. Upon running the model in order to predict the sediment distribution in 2002, the optimization was done by combining MATLAB and Genetic Algorithm models. The research was validated by comparing the results of the calibrated model in 2002 and 2011 with the measured data in the corresponding years. Additionally, Sediment distribution in the reservoir was predicted for 2032 and 2052 using the optimized model. Input data of the calibrated model can be changeable, so the calibrated method can be generalized for other reservoirs as well.

http://jwsr.azad.ac.ir/article_532819_6776b318a01dbe8312913388d618059e.pdf

Calibration of Area-Reduction Empirical Method for Dam Reservoir

One of the objectives of river engineering science in sediments studies is to estimate the amount of sediments and to access appropriate methods of estimating sediment transport capacity of the rivers. In order to design river engineering operations, different mathematical models such as HEC-RAS model can be used. In this case, the first step is to stimulate hydraulic conditions of the flow which can be fulfilled by applying the geometric features of the river and flow hydraulic through the abovementioned model. The present research has estimated the amount of input sediment to the reservoir of Taleghan Dam through mathematical model of HEC-RAS and has determined the best method for estimating the bed load among the seven methods of aforementioned model. Using the required data of the model such as geometric shape of the river, data relating to sedimentary materials of the river, data relating to hydrology or river flow, as well as hydraulic conditions of upstream and downstream system and implementing it, the annual amount of input sediment to the dam reservoir was determined through the sediment statistics of Cling station (upstream) and Lushun station (downstream). Then the floor load obtained from the observed data was compared to the results of seven models. The results showed that the best performance belonged to Wilcok method so that according to hydrometric stations data, in the period between 1980 and 1994 the amount of floor load was about 0.734 million tons per year and according to Wilcock method it was estimated to be 0.635 million tons.

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Solmaz Farajzadeh

Papers

Determining the Best Method for Estimating the Bed Load through HEC-RAS Model (A Case Study for Taleghan Dam)