Journal of Hydrosciences and Environment
Volume:5 Issue: 10, Dec 2021

One way to control the height and volume of water behind the dam is the spillway. One of the most common spillways is an ogee spillway. Today, considering safety , cost and time the optimization of a given project is one of the important issues. A spillway is based on its geometry, can change the flow rate and construction cost. In this study, has tried using numerical methods such as volume of fluid (VOF) to calculate flow rates of three types of spillways. Finally, the numerical results have compared with experimental data. The comparison showed that numerical modeling can accurately predict the rate of flow over the spillway.

Various countermeasures are proposed to control scouring around bridge piers. In the present research, a comprehensive study has been carried out to achieve scouring around two bridges in the north of Iran. The research presents a new set of combined structures against bridges scouring. A 1D numerical model is used for predicting depth of total scouring. According to the numerical results, the supercritical regime is observed in downstream of the bridges. For computing local pier scour Froehlich equation has been selected in the numerical model. Economical comparisons among different proposed combined structures have been done to introduce the best scenario for constructing. The results reveal that making Reno Mattress layer around the piers and Sabo works are needed to control scouring for two case studies. The experiences indicate that every armoring layer has to be situated under active bed layer of the river and better to cover vast area.

Industrial and urban development, Population growth and settlement are common cause of increased pollution. Pollutants are in many instances discharged untreated to rivers due to lack of adequate treatment facilities and high treatment cost. This paper considers assimilative capacity as an important water quality index when the river point source pollution is controllable. The simulation of pollution transport in the river and calculation of assimilation capacity is based on the mathematical equations of pollution propagation with no turbulent flow. The proposed procedure for water quality protection is applied in a hypothetical case study and the obtained results are expressed. The results demonstrate that the river flow variation can modify the assimilation capacity up to 97%.

Intakes are used in rives and channels to control and deviate the flow. The deviation in the intake leads to the formation of a complex flow in the branch channel mouth therefore being familiar with the hydraulic flow in intakes is of great importance. The experimental model was simulated using ANSYS-CFX software in this study. Numerical modeling was carried out in a three- dimensional manner based on k-ω turbulence model. The verification results indicate that the results of the numerical model correspond fairly well to the results of the experimental model with a relative error value (MAPE) of 5%. After verifying the CFX model in this research the effects of different parameters such as discharge ratio, different width ratios, Froude number of the incoming flow, and intake angle were studies on the size of the separation come. According to the obtained numerical results, proper formulas have been developed for anticipating the effects of these parameters on separation zone.

This study investigates effect of turbulence models and boundary layer simulation methods on the accuracy and run time of numerical simulation of the recirculation zone after the backward facing step. Expansion ratio and aspect ratio of the backward-facing step are 2.02 and 8, respectively. The numerical simulations are conducted in 6847 and 4926 Reynolds number (based on the hydraulic diameter of inlet channel and average inlet velocity). The Shear Stress Transport (SST) and the standard turbulence models are utilized and two cases of unstructured mesh are considered:1) near-wall coarse mesh and 2) near-wall fine mesh.The results show that the SST turbulence model predicts the reattachment length more accurately than the model along with enhanced wall treatment. Although, the standard model is less accurate, it's required CPU time is significantly shorter than the SST model.This study investigates effect of turbulence models and boundary layer simulation methods on the accuracy and run time of numerical simulation of the recirculation zone after the backward facing step. Expansion ratio and aspect ratio of the backward-facing step are 2.02 and 8, respectively. The numerical simulations are conducted in 6847 and 4926 Reynolds number (based on the hydraulic diameter of inlet channel and average inlet velocity). The Shear Stress Transport (SST) and the standard turbulence models are utilized and two cases of unstructured mesh are considered:1) near-wall coarse mesh and 2) near-wall fine mesh.The results show that the SST turbulence model predicts the reattachment length more accurately than the model along with enhanced wall treatment. Although, the standard model is less accurate, it's required CPU time is significantly shorter than the SST model.

Landslide term is used for all mass movements on slopes, including falling, overturns and flow debris. Using the potential landslide hazard zonation, areas with high potential of landslide hazard can be detected and so prevent the landslide occurrence with providing appropriate solutions. In this study, the landslide hazard zonation along the water transmission lines of the Shirin-dare Dam Water Supply Pipeline has been done. Studied area is located at the western part of the Northern Khorasan (Bojnord). Study procedure is included of the general geology of the studied area, recognition the most important effective parameters on the landslide phenomena (such as slope, lithology, faults and streams) and also, mapping them as a layer on the basic maps. Then, each layer was validated based on the importance of the effective factors using the maps weighting method in ArcGis software. Finally, the studied area was zoned based on the landslide potential using the overlapping of the various layers.Final zonation map shows that the North, Northwestern and Median parts of the studied area have highest landslide potential. These areas are included of Marl and red Marl and to some extend loss deposits with slopes between 14 to more of 50 degrees. Seemingly, faults (due to low occurrence) and streams (due to drought) have lower effect on the landslide potential. However, the degree of the slope and type of lithology are the most important parameters on the landslide potential, respectively.