Ghufran Ahmed Pasha

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• PhD
• Professor (Assistant) at University of Engineering and Technology Taxila

Debris produced by coastal forest destruction due to the tsunami after the Great East Japan Earthquake caused secondary damage to buildings by collision. To limit such destruction, the trapping action of a finite-length forest was examined in a flume considering the effects of ‘forest density’, ‘debris length to forest width ratio’, and ‘forest wid...

Hill torrents originating from higher elevations in mountainous regions can often lead to flooding in downstream cities and areas. The devastating impact of the 2022 Pakistan floods on human activities in the city of Dera Ghazi Khan has underscored the urgency of effective flood management strategies. In this study, experimental investigations were...

In this research, an assessment of scour depth prediction in meandering channels with spur dikes is made employing machine learning approaches. Efficient determination of the scour depth is therefore vital in the prediction of morphologic aspects and structural stability. The input parameters include sinuosity (S), spur dike locations (Ld), and por...

Climate change and global warming have increased the frequency and intensity of natural hazards such as floods, landslides, and avalanches. These hazards not only have significant individual impacts but are also interconnected, often amplifying their destructive effects. Therefore, it is crucial to manage their consequences and ensure that communit...

Flooding due to extreme events like tsunamis poses a significant threat to coastal areas, often resulting in severe inland inundation. However, coastal vegetation can provide natural defense, helping to minimize the extent of flooding and dissipate tsunami waves. Considering that vegetation can exist in various forms, each potentially influencing w...

A numerical modelling approach has been applied in this study to investigate the three-dimensional flow structure and turbulence characteristics in an open channel with both bank roughness elements (REs) and circular vegetation patches under varying submergence conditions. The bank REs, with lengths of 0.06, 0.04 and 0.02 m, were analysed at pitch-...

This study investigates the role of emerged vegetation in enhancing the performance of submerged spur dikes for better flow control and bank protection in river systems. The research utilizes a numerical model based on Computational Fluid Dynamics (CFD), validated with experimental data. After validation, the study explores various configurations o...

The flow dynamics and river geomorphology are influenced by vegetation patches, which naturally exist in various patterns. Previous studies have not explored the effect of vegetation patches with different shapes placed in a staggered arrangement with varying aspect ratio (AR: longitudinal to lateral patch length). We used a numerical method to exa...

This study aims to investigate the influence of various vegetation patches with varying porosities on the hydraulic properties of a vegetated open channel under subcritical flow conditions. This research work investigated three types of vegetation patches: Rigid, flexible, and a combination of the two. In total five vegetation patches with three di...

Soil erosion on the slope is a major problem in the northern region of Pakistan, causing hill slope instability and landslides. Previous research focused on the assessment of soil erosion in hilly regions caused by intense flooding. However, there is still a gap in investigating the impact of vegetation patterns and densities on the reduction of so...

Spur dike field (SDF) have recently gained attention as habitats for aquatic life. However, limited knowledge exists on how different configurations of roughness elements (RE) interact with recirculating flow in these environments. This study aims to investigate the influence of various RE arrangements (single, double, and triple layers) on hydrody...

Nowadays, combined effects of natural and artificial solutions against flood mitigation are advanced options for researchers. The present paper aimed to explore the effectiveness of dyke and moat for the reduction of fluid force (RFI%) and moment index (RMI%), and overflow volume (∆Q%) under super-critical flow conditions using laboratory and ANN-b...

Emergent vegetation has a significant contribution to resist flow in an open channel. Therefore, the current investigation aims to explore the influence of mixed vegetation patterns (MVP) on various flow characteristics. The current investigation was conducted in a flume to explore the influence of the MVP on flow characteristics under sub-critical...

The evaluation of building vulnerability in flood-prone areas plays a crucial role in understanding flood-induced risk, especially given the potential life-threatening consequences of structural damage during catastrophic flooding events. This study focuses on evaluating the efficacy of various flood defense systems to safeguard buildings. Laborato...

Debris generated by the destruction of houses in a floodplain can cause damage to the structure in the way of floodwater by the impact of different hydraulic forces. In the present study, the impact of different hydraulic forces including impact force, hydrostatic force, hydrodynamic force, fluid force index, and moment index on the house model of...

Vegetation patches, which naturally occur in a variety of patterns, have an impact on the flow dynamics and geometry of rivers. There have been prior studies on vegetation patches, but none have examined the impact of differently shaped vegetation patch, i.e., circle, square and rectangle, and the comparison of these varying patch shapes from an ec...

Scouring is a major concern affecting the overall stability and safety of a bridge. The current research investigated the effectiveness of the various artificial intelligence (AI) techniques, such as artificial neural networks (ANNs), the adaptive neuro-fuzzy inference system (ANFIS), and random forest (RF), for scouring depth prediction around a b...

Flooding is the most common natural disaster throughout the world and requires efficient management. Therefore, the current investigation aimed to explore the impact of a composite defense system comprising dyke and vegetation on flow dynamics and velocity reduction. Experiments were conducted in an open channel setup with an adjustable bed slope a...

Scour poses a significant threat to the stability of bridge piers and abutments. This study investigates the effectiveness of sacrificial piles as a countermeasure to reduce scour around bridge abutments through laboratory experiments. The abutment was modelled in a trapezoidal shape, common in Pakistan, with circular sacrificial piles positioned u...

Pakistan's energy issue is being studied in this study in order to determine if the Khanpur Dam canal has hydroelectric potential. With an emphasis on both technical and financial viability, it aims to maximize the production of electricity by analyzing three options for the installation of machinery. To improve comprehension, a topographical sheet...

Abutment scour is a major cause of bridge failures worldwide, leading to disruptions, economic losses, and loss of life. The present experimental study examines countermeasures against abutment scour using hooked-collar protections on vertical-wall and wing-wall abutments (at 45° and 60°) under different flow conditions. All 60 experiments were per...

Many rivers around the globe are characterized by steep gradients, leading to intense water velocity during flood events, often resulting in spur dikes being submerged. This study concentrates on exploring vegetated spur dikes, aiming not only to prevent from failure but also to enhance ecosystems and landscapes. The approach involves modifying exi...

Emergent vegetation in an open channel is a significant factor in flow resistance and has greater influence on flow characteristics. This paper aims to compare the significance of emergent vegetation under various flow conditions including sub and supercritical flow conditions. The methodology utilizes two types of flow condition (sub and supercrit...

Artificial Intelligence (AI) techniques, such as Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), and dimensional analysis-based empirical equations (DAEEs), can estimate scour depth around bridge piers. AI’s accuracy depends on various architectures, while DAEEs’ performance depends on experimental data. This st...

In the original publication [1], there were two mistakes in relation to the cited references (within the References section) as follows:Reference 52 (Xin-gang et al [...]

Morphological changes in canals are greatly influenced by sediment load dynamics, whose estimation is a challenging task because of the non-linear behavior of the sediment concentration variables. This study aims to compare different techniques including Artificial Intelligence Models (AIM) and empirical equations for estimating sediment load in Up...

Bridge piers that have non-uniform cross-sectional dimensions along their length are called compound piers. The behavior of a significant number of bridge piers is characterized by non-uniformity, which is contingent upon how their foundations are exposed to flow fields. Bridges may fail for a variety of reasons, including design flaws and construc...

Floods have become more frequent and severe across the globe, resulting in considerable loss of human lives, physical infrastructure, and livelihood. It is also applicable to Saudi Arabia, a country recognized for its arid climate, which has witnessed multiple flood events in the recent past; for example, Jeddah, a coastal Saudi city along the Red...

A river's planform pattern changes due to erosion of banks and the bed near the outer bend. The primary cause of these planform changes is the formation of helical flow patterns in response to centrifugal forces. Uncontrolled bed scouring can have a negative impact on the river's geometry, aquatic habitat, and floodplains. To alleviate this scourin...

Nature-based solutions (NBSs) always provide optimal opportunities for researchers and policymakers to develop sustainable and long-term solutions for mitigating the impacts of flooding. Computing the hydrological process in hilly areas is complex compared to plain areas. This study used a laboratory-scaled hillslope model to study rainfall-runoff...

Hill torrents in mountain regions have a very steep slope and water can't infiltrate in the region which results in a flash flood in the area that causes damage to housing crops and land. In the present investigation, for super critical condition a number of flume laboratory experiments were performed to investigate torrential flood energy dissipat...

This study examines the impact of upstream structures on the bulk drag coefficient of vegetation through experimental means, which has not been previously conducted. An embankment model was placed upstream of the vegetation, both with and without a moat/depression. The results showed that the presence of an upstream structure reduced the bulk drag...

Water resources are directly related to the economic conditions of a region. Precise estimation of groundwater is an important step toward better planning and management. This book chapter is dedicated to modelling groundwater in terms of both quantity and quality utilizing ANN (artificial neural networks), ANFIS (adaptive neuro-fuzzy inference sys...

Spur dikes are widely used as river training structures throughout the globe to improve navigation, strengthen flood protection, and save erodible banks. This study investigates the flow behaviour of multiple spurs using similar and different head shapes instead of adding an extra structure. The novelty of the study lies in finding out the best com...

Water scarcity is a major issue for developing countries due to the continuous increase in population every year, the major environmental challenges faced by developing countries such as Pakistan being the scarcity of water. One proposed solution to meet the requirements is to conserve water from rainfall. The process consists of the collection, st...

The present study investigates the effect of upstream structure on the bulk drag coefficient of vegetation experimentally by placing an embankment model with or without moat/depression upstream of the vegetation. The results indicate that in the presence of the upstream structure, the bulk drag coefficient of vegetation is decreased because the ups...

In this paper, the impact of vegetation on various flow parameters that create a complex flow field between the main channel and the two-stage floodplains has been studied. A three-dimensional computational model of Reynolds stress turbulence code FLUENT (ANSYS) simulated the various flow and turbulence characteristics. The geometry consisted of a...

Scarcity of water resources is becoming a threatening issue in arid regions like Gulf. Accurate prediction of quantities and quality of groundwater is the first step towards better management of water resources where groundwater is the major source of water supply. Groundwater modeling with respect to its quantity and quality has been performed in...

In the marine ecological system, the prime role of water management and durability of an ecosystem is being played by the vegetation patches. The vegetation patches in open channels can significantly affect the flow velocity, discharge capacity and hinder energy fluxes, which ultimately helps in controlling catastrophic floods. In this study, the n...

In this study, Computational Fluid Dynamics software (ANSYS Fluent) is used to investigate the turbulence and flow characteristics around spur dike in an open channel. After validating the numerical model with the experimental results, the spur dike was made permeable by providing staggered pores of varying permeabilities (22%, 37%, and 52%). Addit...

The combination of hard (artificial) and soft (natural) solutions i.e., composite defense systems against flooding and tsunami opens a new window for engineering innovation for researchers nowadays. In this study, the experimental investigation of flood energy dissipation phenomena through composite defense systems comprising of embankment and rigi...

The efficiency of flow energy reduction past emergent vegetation has been typically studied assuming a right angle of the vegetated corridor to the flow direction. However, in many real‐world cases the riparian zones of natural, restored, or engineered rivers and waterways, are found at an oblique angle to the flood flow direction. In the current s...

In this study, numerical simulations were performed to investigate the flow and turbulence characteristics of rectangular spur dikes with varying permeability using the Reynolds stress turbulence model developed by three-dimensional (3-D) numerical code FLUENT (ANSYS). In this research, both permeable and impermeable spur dikes were investigated wi...

The purpose of this research was to understand how to minimize the destructive effects of floods by establishing a bio-shield of natural vegetation. Experiments were conducted in a water flume to determine the flow properties under different vegetation conditions whereas; volume of fluid (VOF) multiphase approach with a standard k-ɛ turbulence mode...

Vegetation is an important component of rivers, present naturally alongside the banks. In this research study, three-dimensional computational fluid dynamics (CFD) code ANSYS FLUENT was used to solve the Reynolds Averaged Navier-Stokes equations and to simulate flow features in an asymmetric vegetated compound channel. Three-dimensional flow charac...

Vegetation consists of various types that usually grow over the floodplains or wetlands in different arrangements. It plays a vital role in influencing the flow speed, sediment transport and other flow characteristics. In this study, the numerical simulation was adopted to examine the flow properties for two different submergence depths i.e. 1< z/h...

This paper presents the study of local flow characteristics around permeable and impermeable spur dike suitable for Pakistani rivers especially their tributaries in hilly areas of Pakistan. The flow structure is significantly changed by the type of spur dike. The impact of spur dike in the form of permeable and impermeable especially on resulting t...

In natural rivers, vegetation grows on floodplains, generating complex velocity field within the compound channel. The efficient modelling of the flow hydraulics in a compound channel with vegetated floodplains is necessary to understand and determine the natural processes in rivers and streams. As the three dimensional (3D) flow features are diffi...

Due to extreme storm events, most of the areas in Pakistan are susceptible to large scale inundation which causes significant damages. The role of rigid emergent vegetation has been widely studied in the past for inland flood protection. Volume of Fluid (VOF) modelling is applied in the current study to simulate flow through vegetation in open chan...

Flood flows have the potential to cause substantial damage to infrastructure, mankind, livestock and agricultural land which all stacks up to greatly affect the financial condition of the region. During 2010 Pakistan floods, more than two million houses were damaged partly or totally [1]. To minimize these types of destructions, inland vegetation c...

In this study, a computational method is used to investigate the flow properties and turbulence characteristics through discontinuous and vertically double layered vegetation patches of finite width in an open channel. A three dimensional Reynolds stress turbulence model was implemented utilizing FLUENT (ANSYS). After the validation of the numerica...

The effectiveness of coastal vegetation as a barrier to mitigate a tsunami greatly depends on the magnitude of tsunami and vegetation structure. This paper summarizes a series of laboratory experiments that investigated the upstream flow structure and energy loss due to a hydraulic jump in a steady super-critical flow. The characteristics of the ju...

The concept of hydro-engineering employing the lateral velocity is valuable approach to protect the floodplains from excessive flooding. Reynold Stress Model (RSM) is labored with FLUENT, a 3-D numerical code. In non-symmetric compound channel, lateral velocity distribution is premeditated in efficient two stage floodplain. Using the RSM, it is per...

The concept of hydro-engineering employing the lateral velocity is valuable approach to protect the floodplains from excessive flooding. Reynold Stress Model (RSM) is labored with FLUENT, a 3-D numerical code. In non-symmetric compound channel, lateral velocity distribution is premeditated in efficient two stage floodplain. Using the RSM, it is per...

In the present study, flow around circular and staggered vegetation patches was investigated numerically. For turbulence modelling, the Reynolds‐averaged Navier–Stokes technique and Reynolds stress model were adopted. The numerical model was validated with the experimental data using varying vegetation density and flow velocities. The simulated res...

In order to design a vegetation structure to mitigate floods resulting from extreme events like tsunamis, vegetation density and thickness (width) are important parameters. Flow passing through vegetation faces great resistance, which results in a backwater rise on upstream (U/S) vegetation, increases the water slope inside the vegetation, and for...

The effectiveness of coastal vegetation as a barrier to mitigate a tsunami greatly depends on the magnitude of tsunami and vegetation structure. This paper summarizes a series of laboratory experiments that investigated the hydraulic jump formed on upstream vegetation, and the resulting energy loss due to a jump. The characteristics of the jump wer...

A computational technique to simulate turbulent and vegetated flow in a rectangular open channel was investigated. Reynolds stress model was implemented to the circular vegetation patch flow configuration for the investigation of flow properties and turbulence characteristics. A finite volume-based model was developed using a three-dimensional (3-D...

Since the 2011 Great East Japan tsunami, many improvements have been made in both hard and soft solutions for tsunami mitigation. After the 2011 Great East Japan tsunami, a post-tsunami survey was conducted along the coast in Miyagi Prefecture, which was one of the most tsunami-affected sites because rapid acceleration of the tsunami currents broke...

In the present study, the flow structure of discontinuous double-layered vegetation patches was investigated using a 3D Reynolds stress turbulence model (RSM). The channel domain was built using GAMBIT (Geometry and Mesh Building Intelligent Toolkit). For the simulation and postprocessing, FLUENT (ANSYS) was used to analyze the distribution of the...

Floods resulting from extreme events like tsunamis may inundate widespread inland areas, but vegetation can act as a natural buffer zone to reduce the inundation area and dissipate the energy of flowing water. This paper summarizes a series of laboratory experiments in which the energy loss through emergent vegetation in a steady subcritical flow w...

After the 2011 Great East Japan tsunami, many improvements have been made in both hard and soft solutions for tsunami mitigation. Soma Port area in Fukushima Prefecture was one of the tsunami affected sites where high acceleration of tsunami currents caused trees to break and wash away resulting in extensive damage to inland houses. Contrarily, som...

The aim of this study is to clarify the energy loss mechanism by compound defense system comprising of vertically two different types of vegetation. The layer-1 (L1, lower layer) was considered as fast growing vegetation with a lower height of stem and smaller diameter (e.g. Pandanus odoratissimus) while layer-2 (L2, upper layer) was selected as a...

Floods resulting from extreme events like tsunami may inundate widespread inland area. Although rigid shielding infrastructure (hard protection structures) such as flood protection walls reduce flood risks, but these structures may fail if flow conditions exceed the design threshold. Vegetation (forest) can act as a natural buffer zone to reduce th...

Tsunami is one of the most vulnerable natural hazards in the world. It has vast impact of both tangible and intangible damage, including loss of life, damage to property and goods, and negative impact on social and economic affairs. The tsunami caused by the Great East Japan Earthquake on 11 March 2011 destroyed most of the coastal forest thus prod...

Population increase and climate change are stretching not only the world’s but also Pakistan’s water resources. This has directly been responsible for the recurring patterns of floods and droughts in the country which emphasizes the importance of the fact that efficient practices need to be adopted for water resource sustainability. This study inve...

Mineral aggregates are the basic material of highway pavement construction as they are not only required to resist the internal stresses induced in the pavement due to traffic load, but also the wear due to abrasion by the traffic and adverse weather conditions. The pavement throughout its life should have some friction to facilitate the car whee...

The experiments in an open-channel flume with modeled vegetated weir-like structures have been used to understand how the flow is affected by them. Laser Doppler velocimeter measurements of the water flow velocities over trapezoidal vegetated and non-vegetated weir-like structures (dike, groyne) have been made. The measurements extended to a distan...