https://irju.jdvu.ac.in/jspui/handle/123456789/237 2026-11-05T03:29:44Z 2026-11-05T03:29:44Z Banik, Binoy https://irju.jdvu.ac.in/jspui/handle/123456789/10757 2026-11-03T07:25:22Z 2024-01-01T00:00:00Z

Title: Experimental analysis of scour depth around eccentric circular piers under constant flow conditions Authors: Banik, Binoy Abstract: Scouring by the flow of water in rivers and streams has the greatest impact on alluvial materials beds, but solid rock can also be vulnerable in some cases in mountains stretches of the river. Bridge collapses are a widespread occurrence that causes fatalities, property damage, and halts transportation due to this hydraulic phenomenon called scour. As a result, bridge designers and technician must increasingly understand how soil, water flow, and bridge structures interact. Mostly in the growing cities around the world, traffic load increases, rapidly and more bridges are needed beside the existing one to connect roads and manage traffic. In recent years, researchers have been also studying how to use the natural process of scour to their advantage. They have explored the idea of dredging, which is a method that allows water to naturally move sediments to the sides of channels, without using machines. This process can reduce costs and environmental impact, while still helping to maintain water channels. This study looks into how bridge piers can affect the way water flows and causes erosion around them, especially when the piers are placed in different positions. Understanding how deep the water can dig around these piers, called scour depth, is important to keep bridges safe. The research focuses on how different pier layouts affect the movement of water and erosion. In a controlled environment, we studied how the water erodes and deposits sediment around both front piers and eccentric center piers over time. A total of 24 experiments were carried out using two identical circular bridge piers, each 7 cm in diameter. The distance between the upstream and off-center piers was kept the same, set at 5.185 times the diameter of pier. During the experiments, a steady water flow rate of 30 liters per second was maintained to ensure clear water conditions. The experiments lasted between 2.5 to 10 hours, depending on the specific setup, to observe how the scour changed over time. Various measurements, including the depth, width, length, area, and volume of the scour, were carefully calculated using the data from the experiments. The results were then carefully analysed to determine the most optimal eccentricity arrangement, which is an important issue for bridge designers and dredging professionals looking to improve their procedures. In conclusion, this study investigates the complex dynamics of scouring in connection to bridge design and sediment control. It highlights the potential benefits of using natural scouring processes to relocate sediments gives valuable insights for specialists in this field. Through experimental methods and in-depth research allow for a better understanding of how bridge structures interact with their aquatic environments, resulting in the development of more durable and sustainable infrastructure solutions.

2024-01-01T00:00:00Z Purbi Ali https://irju.jdvu.ac.in/jspui/handle/123456789/10756 2026-11-03T07:20:13Z 2024-01-01T00:00:00Z

Title: Clear water temporal scour around cylindrical pier with circular and airfoil collars fixed on bed Authors: Purbi Ali Abstract: Scouring around the bridge pier is a critical issue in hydraulic engineering as it affects the structural stability and safety of bridges. This natural and complex phenomenon is a leading cause of hydraulic bridge failures, resulting in public safety hazards, and economic losses. Therefore, implementing effective countermeasures to prevent scour around bridge piers is essential. An increase in scour resistance or flow alteration are two major countermeasure techniques. The goal is to counteract the erosive forces of scour-inducing mechanisms using durable engineering materials or, to shift the scour formation away from the immediate vicinity of the pier. The downflow that is responsible for clear water scour can be mitigated by using a collar plate. The present study focuses on the application of the collar as a scour countermeasure technique. This study investigates the temporal development of scour around a circular pier with circular and airfoil collars and also without any such protection. This study also aims to analyze the scour morphology, along with a new predictive model based on the nonlinear regression fonnula and Classification and Regression Tree (CART). a machine learning model to estimate temporal scour depth in the presence of a collar. The predictive ability has been compared with established empirical equations given in the works of literature. A total of 11 experiments are conducted under clear water scour conditions using cohesionless, uniform sand bed material to investigate the effects of collar shape and size on scour development around a pier. The study uses a fixed pier diameter and examines five different circular collars and five different airfoil collars, varying in diameter and length. The experiments aim to assess the effectiveness of these collars in preventing scour and to understand the time-dependent scour patterns at various points around the pier. All tests are conducted with collars fixed at bed level, with a constant flow depth, discharge, and flow intensity. Simultaneously, from the literatures as many as possible, similar experimental inputs and outputs have been collected or extracted for comparative analysis. The results reveal that the temporal development of the scour hole at the pier depends on whether the pier is protected with a collar or not. In the presence of a collar, the development of the scour hole is significantly delayed. It is observed that the larger sized circular collars (bc=36-3.56) are more effective in reducing scour where be and b are the collar and pier diameters, respectively. In the case of an unprotected pier and for smaller-sized circular collars (bc = 1.56-26), the maximum scour depth (Dscm) is observed at the upstream face of the pier (0°) but for the larger sized collars (be = 2.5b-3.56), it is found downstream of the pier (135°). On the other hand, for smaller and larger airfoil collars, Dsem is observed at the side (90°) and the downstream (135°) of the pier, respectively. A significant variation in protection efficiencies is observed when comparing circular collars to an unprotected pier, ranging from 26.23% to 84.96% at the upstream face of the pier and from 4.94% to 74.13% (collar diameter = 3.56) at the side of the pier, depending on collar dimensions. On the other hand, airfoil collars demonstrated higher protection efficiencies, ranging from 83.29% to 89.20% at the upstream face of the pier and from 32.67% to 82.80% (collar diameter = 3.5b) at the side of the pier. For both the circular and airfoil collars, maximum protection efficiency is observed for the larger collars (3.5b). It is also observed that for an unprotected pier, the scour length (1) is less than the scour width (w), and for a circular collar of 1.5b diameter, they are almost the same. However, for the remaining collars > ws. Based on the error analysis and statistical analysis, the CART model and the equation proposed in this study show a better fit with the observed data than the equations derived in previous literatures. This study may aid in protecting bridge pier designs globally under clear water scour conditions, but the predictive efficiency is limited by the use of fixed sediment types, flow conditions, and pier geometry and collar geometry.

2024-01-01T00:00:00Z Roy, Tiyasa https://irju.jdvu.ac.in/jspui/handle/123456789/10755 2026-11-03T07:11:01Z 2024-01-01T00:00:00Z

Title: Comparative trend analysis of minimum temperature using daily gridded data of 72 years at 1° and 0.5° resolution over west bengal Authors: Roy, Tiyasa Abstract: Climate change is expected to significantly increase the frequency of extreme events, with storm events increasing by 21% for every -16.78 °C increase in ocean temperature, leading to severe consequences such as floods, structural damage, and crop loss. Detecting and understanding climate change through trend analysis is an emerging field, though many uncertainties remain. While many studies have focused on warming trends, studies on the coldest years or decades, particularly regarding minimum temperature (Tmin), are rare. Tmin is an important variable in climate models, influencing human health, agriculture, and biodiversity. This study aims to analyze and compare the trends of gridded Tmin data at two resolutions (1° x 1º observed and 0.5° x 0.5° interpolated) over the Indian state of West Bengal (WB) from 1951 to 2022. Using Innovative Polygon Trend Analysis (IPTA), the study examines seasonal, monthly, and decadal trends to understand past and predict future climatic conditions. The findings reveal that the finer 0.5° resolution data gives more detailed results compared to that of 1º resolution, particularly in the central to southern regions of WB. Although the decadal comparison shows minimal differences. Division-wise statistical analysis indicates that trend length (TL) is more consistent than trend slope (TS), with mean TL yielding more stable outputs. IPTA patterns for monthly and seasonal mean Tmin are identified as nearly identical across divisions, while significant differences are observed in the IPTA of monthly and seasonal standard deviations. This study highlights the persistent Tmin discrepancies between north and south Bengal, with finer resolutions suggesting more advanced fluctuations. Recent trends show a higher magnitude of slope than historical decades, emphasizing the increasing sensitivity to climate change. This research contributes to understanding the spatiotemporal variations of hydroclimatic variables, offering insights for mitigating the impacts of climate change on natural and human resources. Future studies should focus on the broader implications of these changes on water resources, human health, and overall climate resilience.

2024-01-01T00:00:00Z Biswas, Mehebul https://irju.jdvu.ac.in/jspui/handle/123456789/10754 2026-11-03T07:04:20Z 2024-01-01T00:00:00Z

Title: Performance and reliability analysis of a horizontal roughing filtration (hrf) system in the treatment of urban pond water: a case study of kolkata city Authors: Biswas, Mehebul Abstract: Almost all real life datasets consist of missing values. These missing values require special attention on analysing the data. One approach to solve incomplete data problems is adoption of imputation techniques. This paper discusses the usage of linear interpolation technique to estimate the missing values. The study involved conducting experiments with a horizontal roughing filter which was present at Fluvial Hydraulics Laboratory, School of Water Resources Engineering, Jadavpur University to assess its capacity to lower turbidity levels. The raw water is collected from Jheel of university and measured turbidity values at inlet and outlet of HRF system during filtration to gauge the filter's efficiency. Then calculate the turbidity values by linear interpolation taking each fourth value of actual turbidity as reference. To assess the effectiveness of linear interpolation, the estimated turbidity values were compared with actual measurements. The thesis investigates the accuracy of the interpolation by calculating the percentage error between interpolated and actual turbidity values. This analysis provides insights into how well linear interpolation performs in filling gaps within the dataset and its impact on the overall evaluation of the filter’s performance. The results indicate that the horizontal roughing filter significantly reduces turbidity 82.92%, demonstrating its effectiveness as a water treatment solution. Linear interpolation was found to be a useful technique for estimating missing turbidity values, with error 9.825%. Generally within an acceptable range, suggesting that it is a reliable method for handling incomplete data in turbidity studies. This study contributes to the understanding of horizontal roughing filter systems and their application in turbidity removal. It also highlights the importance of accurate data interpolation in water quality assessment and provides insights into the reliability of different methodologies for handling incomplete data.

2024-01-01T00:00:00Z