Journal of Hydraulic Structures
Volume:9 Issue: 3, Autumn 2023

This research addresses the essential need for assessing and managing water quality in reservoirs, which play a pivotal role in various socioeconomic aspects. To achieve this, a stepwise automatic calibration approach is proposed, specifically targeting the CE-QUAL-W2 model. This two-dimensional hydrodynamic and water quality model is widely employed in studies worldwide. Calibration, a fundamental aspect of model development, is complex and traditionally relies on manual, trial-and-error methods, which can be time-consuming and require substantial expertise. In this study, an alternative approach is introduced, incorporating the JAYA optimization algorithm, which reduces the complexity associated with fine-tuning optimization parameters. Furthermore, a clustering framework is adopted, grouping related variables for independent calibration. The research is conducted on the Dez reservoir in southwest Iran, using a two-step calibration process. The first step focuses on hydrodynamics, while the second step addresses water quality variables, including phosphate, ammonium, nitrate, and dissolved oxygen. The proposed methodology applied to Dez reservoir and tested against the observed data, where it demonstrates promising results.

Coastal areas are usually heavily exploited. Numerous anthropogenic constructions are developed along the coastal areas for recreational, economic and/or cultural purposes. They influence the coastal hydrodynamics. Therefore, identifying the source of coastline transformation is essential for controlling these modifications and develop a sustainable coastal area. Simultaneous deployment of numerical modeling and RS imageries is a suitable approach for understanding hydrodynamic processes in coastal areas. In this study, the hydrodynamic condition of the Beris Port area located in the Makran region, north of the Gulf of Oman, has been analyzed using MIKE-21 software package, RS, and GIS techniques. Our results reveal the accretion of 20.97 ha adjacent to the breakwater since 1988. We also found that the shore near the port is heavily accumulated by sediment, while this is not the case for those shore far from the port. According to our results significant wave height is considerably low inside the port, even during the high season of summer, which is due to the construction of the port and the bay shape of the coast. The current speed, inside the port, is also low (0.01 m/s). The current adjacent to the port is in the opposite direction to the main current direction of the region, causing nearshore accretion. Therefore, it is believed that the accretion problem is due to the poor design of the breakwaters' layout. Thus, a new alignment for the breakwater is suggested, taking into account the hydrodynamics and morphodynamics of the area.

Cylindrical piles are often used in most of coastal and offshore structures such as bridges, wharfs, offshore wind turbine foundations and Oil platforms. Most of these structures are installed in shallow water and exposed to strong currents, waves and broken waves. These phenomena can cause scour around them which can damage their structural integrity and stability. In literature, scour process around the cylindrical piles under currents and waves have been studies frequently. However, there are very little knowledge about the bed forms due to the broken waves. In this paper, the effect of broken waves on the characteristics of bed forms around a cylindrical pile has been studied experimentally in a large wave flume. The three-dimensional bed topography was measured by Close Range Photogrammetry. Vortex ripples and truncated cone scour with vortex ripples were the main observed scour pattern. Shields parameter as well as Keulegan-Carpenter (KC) number were used as the non-dimensional parameters for bed form classification. It is noticed that the ripple height and ripple steepness for broken regular waves is less than non-breaking regular waves. However, the relative equilibrium scour depth for broken waves is larger than non-breaking waves.

The snow budget in mountainous river basins reacts sensitively to temperature fluctuations. Therefore, the desired temperature increase due to climate change could significantly affect the snow budget in the future. These effects could lead to significant changes in the hydrological regime of river basins such as the Central Alborz basins. The aim of this study is to investigate the application of MODIS land surface temperature (LST) data in studying snow climatology. The analysis included several important snow parameters derived from the snow depletion curves (SDCs). These curves were extracted from cloud-reduced MODIS products of daily snowpack for each river basin studied. Correlations between these snow parameters and the MODIS LST data were then investigated. The results show that several snow parameters variations are significantly correlated with MODIS LST data over past 20 years (2002-2022). Specifically, Maximum Snow Cover (MSC), Maximum Snow Cover Day (MSCD), Snow Melt Ending Day, and Accumulation-Ablation Period (AAP) exhibited substantial correlations with LST, as indicated by the Tau correlation coefficients of -0.74, -0.31, -0.51, and -0.35, respectively, at a confidence level of 90%.The SMED was found to be the most sensitive snow parameter to MODIS LST variations. Strong correlations were observed between SMED and LST across all studied subbasins, with an overall Pearson correlation coefficient of -0.79 and a Tau correlation coefficient of -0.51 for the whole study area. The results of this study show that MODIS LST data successfully explain the dependencies between snow budget and temperature in the Central Alborz basins.

Numerical simulations were carried out in a compound meandering channel to investigate the effect of building arrangements in the floodplain on the flow field in the main channel. Three types of structural arrangements were used: structural obstacles parallel and perpendicular to the flow of the floodplain (MGT and MHT), and checkered structural barriers (MFT). Numerical simulation results showed that the building arrangements in the floodplain can significantly change the transverse velocities and flow angle in the main channel. Near the convex arc of the apex sections (CS1 and CS7), the transverse flow velocity increased by changing the building arrangements from parallel to the floodplain flow (MGT1) to perpendicular to the floodplain flow (MHT1) (517% increase), but in the center of the main channel in the middle section (CS4), the transverse flow velocity decreases with the change of the arrangement from the parallel state (MGT1) to the perpendicular state to the floodplain flow (MHT1) (47% decrease). In the CS4, the maximum transverse flow velocity in cases MFT1, MGT1 and MHT1 decreases by 84%, 49% and 80% on average respectively, compared to the smooth floodplain (MAT). In the center of the CS4, the change of arrangement has the greatest effect on the flow angle, so that the lowest flow angle is observed for cases with the arrangement of buildings perpendicular to the floodplain flow and checkered (MHT and MFT). Also, in the middle section, the strength of vortices rotation increases significantly in the case of MGT1 compared to the case of MHT1.

One of the important topics in river engineering is the design of stable alluvial channel geometry in the regime mode (dynamic balance between erosion and sedimentation) including the width, depth and slope. In this research, the ANFIS and ANFIS-PSO models were used to model the geometry parameters of stable channels. To achieve this objective, we utilized a comprehensive dataset comprising 410 data series sourced from 15 different channels, encompassing various types such as straight and meandering, as well as natural and laboratory. In each measurement, information on the flow rate (Q), average particle diameter (d), shear stress (τ), top width of the channel (W), average depth of flow (h) and longitudinal slope of the channel (S) was collected. Randomly, 70% of the data was used for training, and the remaining 30% was used for validation of the ANFIS and ANFIS-PSO models. Totally, 42 models were derived from the combination of 7 input data sets (Q, d, and τ) and employed both ANFIS and ANFIS-PSO, models to estimate the W, h, and S as the three types of outputs. In modeling of the W and h parameters, the best input was the Q, which the R2, CRM and NRMSE for all data with the ANFIS model were equal to 0.954, -0.029, 0.567 and with ANFIS-PSO model were 0.912, -0.042, and 0.487, respectively. Also, to estimate the S, the modeling results had error. In general, the modeling results with the ANFIS-PSO model were more accurate than the results of the ANFIS model.