Numerical study on the effect of the spur dikes on sedimentation pattern

The spur dikes are structures that usually used for flow diversion from erodible wall and they usually create a appropriate path for directing the flow, flood control, protection of external walls, and some other cases. Through modifying the hydraulic conditions and creation of smooth flow, spur dikes can decrease water erosion force and power of sediment transport. In this study, the channel and spur dike related to the Heltz Laboratory model have been simulated using Flow-3D numerical model. The RNG turbulence model has been applied for turbulence modeling. The turbulent flow field around inclined spur dike and the effect of such parameters as angle, hydraulic conditions and sedimentation pattern have been investigated. The results showed that increasing the angle of spur dike affects the length and width of sedimentation area. When angle of spur dike increases from 90 to 120 deg, the width and length of the sedimentation area will increase up to about 71 and 92 percent, respectively. Keywords: Inclined spur dike, Flow pattern, Sedimentation, Flow-3

Numerical analysis of stream renovation using MIKE 11-GIS and HEC-RAS5

The main purpose of river system is to renovate its old processes. This article represents the results of two numerical models and a field site screening results for the river renovation in Idaho, U.S.A and some restoration methodologies that have been used to better understand possible renovating strategy. Ecological recovery methods using a degraded stream ecosystem have been found after estimating a channel design's capability. Despite these representing methods it is hard to present the most effective method to get efficient renovative outcomes. Two hydrodynamics modelling (MIKE 11-GIS and HEC-RAS5) and field site screening are used to evaluate pre- and post-renovation modifies in 35 laboratory experiments and biological performance indicators. Movement formed between 1994 and 2014 have been considered in this research. Ecosystem improvements have been evaluated to compare the pre-post renovation situations by considering the parameters such as water surface elevation, lower slope, shear stress, depth, wet perimeter, and velocities. The numerical model results for all mentioned parameters show that after the completion of phase I, II, III and IV, the sinuosity of the channel will be very close to the 1986 condition. The sediment carrying capacity and potential use of MIKE 11-GIS, hydrodynamic model for scour has been reduced throughout the lower reaches of the project site, where the channel slope is at its steepest position, and a close match with the field site screening and have been shown and presented as graphs

Assessing the effects of increased impervious surface on the aquifer recharge through river flow network, case study of Jackson, Tennessee, USA

Understanding pathways connecting urbanization to the recharge process across the land surface and river environment is of great significance in achieving low-impact development. Accordingly, the contribution of an urbanized region with a low and high development rate, along with the expected overflow into the river network resulting from increased impervious surfaces, was assessed in the recharge rate at Jackson, Tennessee. To this end, first, the losses were calculated using the standard and modified SCS-CN methods for the maximum probable flood condition. Then, TUFLOW was applied to simulate the two-dimensional flood for a historic 24-h probable maximum precipitation event with a 100-year return period. The results of TUFLOW were later calibrated using the results of standard and modified SCS-CN methods. A calibrated MODFLOW was employed to assess the effects of urbanization and, consequently, the plausible extended river network on the recharge rate. Results revealed that the West Wood contribution in groundwater recharge was 19 % less than the Musa Street, while it supplies approximately 2.7 % more flow than Musa Street. The performance evaluation results of TUFLOW showed 0.4916 and 0.689 as Nash–Sutcliffe, respectively, for the standard and modified SCS-CN methods. Although the flow velocity and depth were respectively increased by 3.3 % and 8.3 % under modified SCS-CN compared to the standard one, the soil water storage capacity remained constant at equal to 0.16 mm. Results revealed that the maximum soil water storage capacity was fulfilled soon through the modified SCS-CN than the standard method leading to higher flood volume and discharge. To this end, the discharge resulting from modified SCS-CN was approximately 1.5 times higher than that in the standard method under the same precipitation condition. Our findings suggest that designing any construction, mainly dams downstream, based on the modified SCS-CN estimations will provide more safety, particularly in crowded regions. Also, overflowing the excess surface runoff into the river network resulted from the increased impervious surface amplifying the flow volume, depth, and velocity across the river networks, finally leaving the area without increasing the aquifer\u27s recharge rate. The results provide insights into possible sustainable development options and flood management in the built-up area

Numerical analysis of surface hydrogeological water budget to estimate unconfined aquifers recharge

Under changing climate, groundwater resources are the main drivers of socioeconomic development and ecosystem sustainability. This study assessed the contribution of two adjacent watersheds, Muse Street (MS) and West Wood (WW), with low and high urban development, to the Memphis aquifer recharge process in central Jackson, Tennessee, USA. The numerical MODFLOW model was created using data from 2017 to 2019 and calibrated using reported water budget components derived from in-situ data. The calibrated MODFLOW model was then used to investigate the impact of high and low urban developments on the recharge rate. The hydraulic parameters and recharge rates were optimized by adjusting the groundwater level based on the observed water level using PEST. The stochastic modeling was also carried out using the Latin Hypercube approach to reduce the uncertainty. The calibration results were satisfactory, with RMSE of 0.124 and 0.63 obtained in the WW and MS watersheds, respectively, indicating accurate estimation of the input parameters, precisely the hydrodynamic coefficients. The study results indicate that, per unit area, the MS watershed contributes 119% more to recharge and 186% more to riverbed leakage compared to the WW watershed. However, regarding total recharge and riverbed leakage, the WW watershed contributed more than the MS watershed. The results of this study have enhanced the knowledge of the impact of urbanization on hydrology and the recharge process in watersheds with diverse land uses

Numerical study on the effect of the spur dikes on sedimentation pattern

The spur dikes are structures that usually used for flow diversion from erodible wall and they usually create a appropriate path for directing the flow, flood control, protection of external walls, and some other cases. Through modifying the hydraulic conditions and creation of smooth flow, spur dikes can decrease water erosion force and power of sediment transport. In this study, the channel and spur dike related to the Heltz Laboratory model have been simulated using Flow-3D numerical model. The RNG turbulence model has been applied for turbulence modeling. The turbulent flow field around inclined spur dike and the effect of such parameters as angle, hydraulic conditions and sedimentation pattern have been investigated. The results showed that increasing the angle of spur dike affects the length and width of sedimentation area. When angle of spur dike increases from 90 to 120 deg, the width and length of the sedimentation area will increase up to about 71 and 92 percent, respectively. Keywords: Inclined spur dike, Flow pattern, Sedimentation, Flow-3

A New Method for Base-Slab Analysis of a Dock Settling Basin

This paper suggests a new method of computing interior forces and deformations of the base-slab of a dock settling basin. The base element is considered as a finite beam under the action of bending supported by subgrade soil. The deformation of the subgrade is determined through the Fuss-Winkler model. The basic parameter (i.e., coefficient of subgrade reaction) of this model is a nonlinear parabolic equation along the length of the beam. The solution of this model leads to an ordinary differential equation that can be solved by using boundary conditions and Picard limit of a sequence method. After the solution of the equation, the deformations and interior forces are computed at any arbitrary cross section of the beam and the results of this study are compared with the other methods offered in the literature and compatible outcomes are achieved